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Optical Coherence Tomography Assessment of Retinal Nerve Fiber Layer Thickness Changes after Glaucoma Surgery
Abstract
To assess changes in retinal nerve fiber layer (NFL) thickness in glaucoma patients after filtration surgery by using optical coherence tomography (OCT).
Retrospective observational case series.
Thirty-eight eyes of 31 glaucoma patients who underwent trabeculectomy or a combined procedure of cataract extraction and trabeculectomy were evaluated retrospectively.
Eyes were imaged with OCT before surgery (1 week to 6 months before surgery; mean +/- standard deviation [SD], 71.3 +/- 61.2 days) and after surgery (6-12 months after surgery; 247.2 +/- 63.5 days) to measure peripapillary NFL thickness.
Changes in mean and segmental NFL thickness with respect to age, postoperative change in intraocular pressure (IOP), preoperative visual field test global indices, and change in visual field global indices.
A significant increase in the overall mean NFL thickness was present after surgery (P < 0.0001). Segmental analysis found a significant increase in NFL thickness in the nasal, superior, and temporal quadrants. IOP decreased after surgery from 22.0 +/- 6.4 mmHg to 11.4 +/- 4.7 mmHg (mean +/- SD). Twenty-eight (73.7%) of 38 eyes had an IOP reduction >30%. The mean NFL thickness increase (0.5- microm/mmHg decrease of IOP) was significantly correlated with the IOP reduction (r = -0.41; P = 0.03). No correlation was found between NFL thickness changes and age, preoperative visual field global indices, or change in visual field global indices.
A significant increase of the mean NFL thickness, which was related to IOP reduction, was detected after glaucoma filtration surgery.
... Surgical IOP reduction may affect measurements of routine tests performed in glaucoma patients, bringing difficulties in the investigation of possible disease progression. [5][6][7][8][9][10][11][12][13] Structural reversibility in the optic disc after glaucoma filtering surgery was demonstrated in children as well as adults by photography and automated imaging instruments. [6][7][8][9][10] Previous studies observed changes in ocular posterior segment measured by OCT after surgical reduction of IOP. ...
... [6][7][8][9][10] Previous studies observed changes in ocular posterior segment measured by OCT after surgical reduction of IOP. [11][12][13] Improvements in optic disc parameters such as cup depth, prelaminar tissue, and neuroretinal rim were identified. [13][14][15] Changes in peripapillary RNFL thickness measured by time-domain (TD) OCT after glaucoma surgery have already been suggested by some reports, 11,16 but not confirmed by others using spectral-domain OCT (SD-OCT). ...
... [11][12][13] Improvements in optic disc parameters such as cup depth, prelaminar tissue, and neuroretinal rim were identified. [13][14][15] Changes in peripapillary RNFL thickness measured by time-domain (TD) OCT after glaucoma surgery have already been suggested by some reports, 11,16 but not confirmed by others using spectral-domain OCT (SD-OCT). 13,14 There is also evidence of macular thickness increase measured by TD-OCT and SD-OCT associated with IOP reduction after uncomplicated glaucoma filtering surgery. ...
Purpose
To evaluate the magnitude of change in optic disc, peripapillary retinal nerve fiber layer (RNFL) and macular parameters measured by swept-source optical coherence tomography (SS-OCT) in glaucomatous eyes after filtration surgery, and to determine any possible relationship between these measurements and baseline factors.
Patients and Methods
This multicenter, prospective, consecutive observational study included patients with open-angle glaucoma who required glaucoma filtering surgery (surgical group, 29 eyes) and those with stable disease (control group, 25 eyes). Patients from the surgical group underwent measurement of optic disc, peripapillary retinal nerve fiber layer (RNFL) and macular parameters before and after surgery.
Results
In the surgical group, there was a significant increase in rim area and a significant decrease in the linear cup/disc ratio, vertical cup/disc ratio and cup volume 1 and 2 months postoperatively (p< 0.05). No significant change in the mean RNFL thickness and also sectorial measurements were observed from baseline to 1 and 2 months after surgery (p>0.05). Furthermore, significant increases in macular parameters were observed until 2 months after surgery (p<0.05). No significant changes were observed for all SS-OCT measurements in the control group. There was a significant correlation between the magnitude of the structural measurements change and the IOP reduction for two topographic parameters (rim area and linear cup-disc ratio) and macular average thickness 1 month and 2 months postoperatively.
Conclusion
In open-angle glaucoma patients submitted to surgical IOP reductions, improvements in topographic and macular OCT parameters measured by SS-OCT were observed for at least 2 months.
... In these studies, it is suggested that the thickness of prelaminar tissue is influenced by IOP. 13,15,[19][20][21] According to research articles about NPDS, postoperative IOP-reduction is not associated with significant RNFLT-change at 6 months postoperatively. 13,14 Studies reporting on the condition of lamina cribrosa and peripapillary RNFLT after trabeculectomy or NPDS draw the same conclusion: changes in the morphology of the optic nerve head attributable to postoperative IOP-changes (anterior displacement of the lamina cribrosa, reduced cup volume and increased rim area) are not necessarily accompanied by an increase in the RNFLT. ...
... According to some authors, there is an 0.5μm increase in RNFLT in case of a 1mmHg IOP-reduction, according to others, a 1.3 mmHg IOP-lowering is needed to achieve this goal. 14,19,26 There is not a tight correlation between the morphological changes of the optic nerve head and RNFLT. Explanation for this observation might be that IOP-reduction does not result in an increase of the number of axons, rather, it causes relaxation of the axons and reduces tissue strain, and this would lead to a morphological change of the optic nerve head. ...
... This fact may lead to false interpretation of RNFLT-increase after trabeculectomy. 15,19,20 Authors evaluating RNFLT-changes after NPDS surgery analyse patients' records with dissimilar pre-and postoperative RNFLT: Rebolleda measured 66.6 µm mean RNFLT in her patients group, whereas Krzyżanowska-Berkowska's patients had 61.6 µm average RNFLT at baseline. Among our subjects the mean RNFLT was 60.50µm at baseline and 59.63µm at 12-month end point of the followup. ...
Purpose
The goal of our study was to investigate changes in intraocular pressure (IOP), best-corrected visual acuity (BCVA), and retinal nerve fibre layer thickness (RNFLT) after CO2 laser-assisted deep sclerectomy (CLASS).
Methods
We carried out uncomplicated CLASS surgeries and a 12-month follow-up on 22 open-angle glaucomatous (OAG) eyes of 22 patients. IOP, BCVA, and RNFLT with spectral-domain optical coherence tomography (SD OCT) were recorded before and 1, 3, 6, 12 months after surgery.
Results
Mean age of patients was 68.1 years. IOP decreased from preoperative 28.45±5.99 SD mmHg (mean±standard deviation) to 15.09±2.40 mmHg (p=0.00039) at 12 months after surgery. BCVA-change from preoperative 0.34±0.38 SD (LogMAR) to 0.37±0.41 SD (LogMAR) was not significant (p=0.2456). RNFLT-change from preoperative 60.50±18.15µm to 59.63±17.52 µm at 12 months postoperatively was not significant (p=0.056). Qualified success rate of CLASS surgery was 72.7%, whereas complete success rate was 64% at 1 year postoperatively.
Conclusion
Successful CLASS surgery efficiently reduced IOP. At postoperative 12 months, RNFLT and BCVA were not reduced significantly. There was no significant glaucomatous progression after surgery encountered in respect of investigated parameters.
... Similarly, increase in RNFL thickness postoperatively is the reversal or rebound of the physical compressive effect on the RNFL by the elevated preintervention IOP, leading to a recovery of normal shape and size by the retinal ganglion cell axons. [4][5][6][7][8][9] in the study. These patients were examined clinically for various signs of open angle glaucoma. ...
... Hence, inferior quadrant thickness showed significant improvement in the 1 st week postoperatively but were tending to preoperative values in the 1 month and 3 rd month of follow-up [ Table 1].Similar results were observed by Raghu et al. (2012) in their study; the RNFL parameters, average of inferior and temporal quadrant RNFL thickness increased significantly at 1 week after surgery, but reverted to baseline levels at the subsequent follow-up visits. Aydin et al. (2003) in his study found a significant increase in the peripapillary nerve fiber layer (NFL) thickness, as determined by OCT, after glaucoma filtration surgery. ...
... Although no statistical significance was shown, yet numerical improvement in thickness was observed [ Table 4]. Aydin et al. (2003) studied that NFL thickening was significant for the overall measurement and in all quadrants except the inferior quadrant. Segmental analysis should be performed cautiously because the reproducibility decreased for quadrant measurements in glaucoma individuals, especially in the temporal and nasal quadrants. ...
... These marks were used to calculate the MRW and the MRA. 3 Minimum rim width represents the minimum distance from the inner opening of the BMO to the ILM through which optic nerve axons must pass; MRA represents the minimum area. The angle of the vectors defining MRW and MRA (i.e., the angles above the reference plane at which these minima occurred, averaged across B-scans) also were tabulated. ...
... 16,17 However, this result contradicts other prior studies that demonstrated an increase in the RNFLT after surgery to lower IOP. 3,26 It is important to note that the study by Yamada et al 26 is limited because of the use of a scanning laser polarimeter to measure the RNFL without correction for the corneal polarization axis, which may have been altered by surgery. 27 Our data also contradict findings reported in 2002 by Aydin et al, 3 who used a noncommercial prototype OCT device with lower resolution. ...
... 3,26 It is important to note that the study by Yamada et al 26 is limited because of the use of a scanning laser polarimeter to measure the RNFL without correction for the corneal polarization axis, which may have been altered by surgery. 27 Our data also contradict findings reported in 2002 by Aydin et al, 3 who used a noncommercial prototype OCT device with lower resolution. ...
Purpose
Ophthalmologists commonly perform glaucoma surgery to treat progressive glaucoma. Few studies have examined the stability of OCT neuroretinal rim parameters after glaucoma surgery for ongoing detection of glaucoma progression.
Design
Longitudinal cohort study.
Participants
Twenty eyes (16 participants) with primary open-angle glaucoma who had undergone trabeculectomy.
Methods
We calculated the change in OCT parameters (minimum rim area [MRA], minimum rim width [MRW], Bruch’s membrane opening [BMO] area, mean cup depth [MCD], anterior lamina cribrosa surface depth [ALCSD], prelaminar tissue thickness, retinal nerve fiber layer thickness [RFNLT]) during an interval from the visit before the surgery to the visit after the surgery, a span of approximately 6 months. We also calculated changes in the same eyes over 2 separate 6-month intervals during which trabeculectomy did not occur to serve as a control. We compared these intervals using a generalized linear model (with compound symmetry correlation structure), accounting for the correlation between intervals for the same eye.
Main Outcomes Measures
Minimum rim width, MRA, angle above the reference plane for MRW and MRA, BMO area, MCD, mean ALCSD, prelaminar tissue thickness, RNFLT, and visual field parameters (mean deviation, pattern standard deviation, and visual field index).
Results
The intervals during which trabeculectomy occurred showed a significant decrease in intraocular pressure (–9.2 mmHg; P < 0.001) when compared with control intervals. Likewise, the following neuroretinal rim parameters showed significant changes with trabeculectomy: increased MRW (+6.04 μm; P = 0.001), increased MRA (+0.014 mm²; P = 0.024), increased angle above reference plane of MRW (+2.64°; P < 0.001), decreased MCD (–24.2 μm; P = <0.001), and decreased mean ALCSD (–18.91 μm; P = 0.006). This is consistent with an increase in rim tissue thickness and a more anterior position of the internal limiting membrane and ALCS relative to the BMO plane. Conversely, RNFLT change was not significantly different between trabeculectomy and control intervals (P = 0.37).
Conclusions
Trabeculectomy resulted in anatomic changes to the optic nerve head rim associated with reduced glaucomatous cupping. The RNFLT may be a more stable measure of disease progression that clinicians can use to monitor across intervals in which glaucoma surgery occurs.
... Numerous studies evaluated the RNFL thickness after glaucoma surgery [15,[26][27][28][29]; fewer studies considered the RNFL thickness and the LC position [4,13]. The main site of glaucoma damage is believed to be at the lamina cribrosa, though release of pressure on the nerve fibers passing through the lamina should also result in changes in RNFL thickness after IOP reduction. ...
... The main site of glaucoma damage is believed to be at the lamina cribrosa, though release of pressure on the nerve fibers passing through the lamina should also result in changes in RNFL thickness after IOP reduction. Some studies have shown increased RNFL thickness following glaucoma surgery [27,29], while other studies [15,28,30] showed no change in RNFL thickness on OCT following IOP reduction. However, it is difficult to compare individual studies, due to the large differences in the groups qualified for the study (a combination of POAG and juvenile open-angle glaucoma in one group [27], different baseline values for MD (− 7.0 ± 6.8 dB [15]; MD − 20.4 ± 8.6 dB [29]; − 15.37 ± 10.96 dB in the present study), or analysis of the average RNFL thickness [13] and thickness by quadrants [15,27,29]. ...
... Some studies have shown increased RNFL thickness following glaucoma surgery [27,29], while other studies [15,28,30] showed no change in RNFL thickness on OCT following IOP reduction. However, it is difficult to compare individual studies, due to the large differences in the groups qualified for the study (a combination of POAG and juvenile open-angle glaucoma in one group [27], different baseline values for MD (− 7.0 ± 6.8 dB [15]; MD − 20.4 ± 8.6 dB [29]; − 15.37 ± 10.96 dB in the present study), or analysis of the average RNFL thickness [13] and thickness by quadrants [15,27,29]. ...
Purpose:
The purpose of the study is to assess the displacement of lamina cribrosa (LC) and prelaminar tissue area (PTA) changes following trabeculectomy and non-penetrating deep sclerectomy (NPDS) using spectral-domain optical coherence tomography (SD-OCT) with enhanced depth imaging technology.
Methods:
A total of 30 patients underwent glaucoma surgery. Sixteen patients underwent trabeculectomy, and 14 patients undertook NPDS. Serial horizontal B-scan images of optic nerve head (ONH) were obtained using SD-OCT preoperatively, and at 2-week, 1-, 3-, and 6-month postoperative visit (6 pv). LC displacement magnitude and PTA changes were determined from selected B-scan images. Correspondingly, OCT retinal nerve fiber layer (RNFL) parameters were measured.
Results:
Intraocular pressure (IOP) decreased from 27.4 ± 10.3 mmHg (mean ± standard deviation) to 10.2 ± 4.0 mmHg (P = 0.011) and from 19.9 ± 4.0 mmHg to 11.9 ± 3.6 mmHg (P = 0.012) at 6 pv, for trabeculectomy and NPDS, respectively. There was a significant decrease in the LC depth from a baseline glaucomatous LC displacement of 468.0 ± 142.4 to 397.6 ± 125.2 μm in the trabeculectomy group (P = 0.001) and from 465.2 ± 129.6 to 412.0 ± 122.4 μm in the NPDS group (P = 0.029) at 6 pv. The PTA differed between the procedures at baseline (P = 0.002), but was not statistically significant postoperatively. Multivariate analysis for all patients including age, magnitude of IOP reduction, baseline glaucomatous LC displacement, magnitude of LC displacement, and the type of surgery revealed that only the magnitude of LC displacement was associated with significant RNFL thinning on average (r2 = 0.162, P = 0.027) and in the following sectors: temporal superior (r2 = 0.197, P = 0.014), temporal (r2 = 0.150, P = 0.034), and nasal superior (r2 = 0.162, P = 0.027).
Conclusions:
Decrease in the LC depth after NPDS surgery can be observed at 6 pv. Regardless of the performed procedure, magnitude of LC displacement is associated with significant, focal RNFL thinning.
... Although the positive impact of the glaucoma filtration surgery on IOP is generally accepted (Anonymous, 2017), the influence of this manipulation on the structural and functional parameters of the eye is still not clear. There are several studies that evaluated long-term results after trabeculectomy (Aydin et al., 2003;Chang et al., 2007;Rebolleda et al., 2007). Raghu and colleagues showed that RNFL thickness increases and cup area decreases for a transient period after glaucoma surgery but reverts back to preoperative values within three months (Raghu et al., 2012). ...
... Unfortunately, the surgery does not restore any visual field already lost (Lamping et al., 1986). However, some improvements in visual function and structural parameters have been observed (Aydin et al., 2003;Chang et al., 2007;Raghu et al., 2012). Raghu with colleagues noted shortterm fluctuations in RNFL thickness which temporarily increased but the values reverted to normal within three months. ...
... Conflicting results have been reported regarding improvement in the postoperative RNFL thickness. Several studies have reported a significant change in RNFL thickness following IOP reduction (Aydin et al., 2003;Sarkar et al., 2014). Similarly, the study of Chang et al. found a significant increase in RNFL, but with no correlation with IOP (Chang et al., 2007). ...
Glaucoma filtration surgery (trabeculectomy) is an effective glaucoma treatment method that provides significant intraocular pressure (IOP) reduction. Indications for this method are in cases where other forms of therapy, like medicines or lasers, have failed, other forms of therapy are not suitable (compliance or side-effects are a problem), in cases where a target pressure is required to prevent clinically significant disease progression that cannot be reached with topical medications and/or laser and in cases that have such advanced glaucoma and high IOP at presentation that other forms of treatment are unlikely to be successful. The aim of this study was to evaluate the effect of glaucoma surgery on the structural and functional eye parameters at different stages of glaucoma. A total of 96 eyes of 96 patients (only one eye from each patient) with different stages of glaucoma (stages 2 to 4) who were undergoing trabeculectomy were recruited. Quadrant retinal nerve fibre layer RNFL) thickness (33 patients), cup/disc vertical and horizontal ratio (36 patients) and MD of visual fields (27 patients) were analysed up to one week before and 1 month after the successful surgery. The results show that the MD value was slightly improved in 50%, 85.7%, and 71.4% of patients with glaucoma stages 2, 3, and 4, respectively. The mean RNFL of all four optic nerve head quadrants increased slightly after the surgery for patients with glaucoma stage 2; in contrast, a decrease in the mean RNFL values for all four quadrants was observed for patients with glaucoma stage 4. Statistically significant changes in the mean values for the optic nerve horizontal c/d ratio after glaucoma surgery were observed (p = 0.033) in contrast to the vertical c/d values (p = 0.77). In total, improvement of the horizontal and vertical c/d ratio was detected in 61.1% and 55.6% of the glaucoma patients, respectively. Although the observed changes were statistically insignificant, the positive influence of glaucoma surgery on the structural and functional eye parameters was more pronounced in moderate stages than in advanced or severe stages of glaucoma.
... 2,4 Comparison of ocular perfusion before and after glaucoma filtering surgery has shown that the amount of increase in vessel density is directly proportional to the amount of IOP reduction, 4 thought to be related to reduced lamina cribrosa curvature and improved ONH circulation. 5,6 In our patient, by relieving the mechanical stress at the lamina cribrosa following IOP reduction by 50-70%, the average perfusion pressure improved by 1.3% and flux index increased by 0.053. ...
... 7 According to a study, there was a notable increase in RNFL thickness with IOP reduction after glaucoma filtering surgery, which has been attributed to decreased strain exerted on the axons. 5 The damaged RGCs regain their function partly, resulting in reversibility of the VF defect. 8 Our case showed that the nasal step defect was reversible alongside improvement of ONH perfusion with prompt and adequate IOP reduction in this young patient. ...
Background: Patients with juvenile onset ocular hypertension (OHT) have high intraocular pressure (IOP) and may develop early glaucomatous disc damage. Case presentation: A 26-year-old woman with family history of glaucoma was diagnosed with OHT at age 18. Her vision was 6/6, with a bilateral cup-to-disc ratio of 0.5, normal visual field (VF), and IOP in the mid-teens on 2 topical antiglaucoma medications. The patient started having IOP spikes (20–48 mmHg) in her left eye despite maximum tolerable medical therapy, associated with intermittent headache and nasal step defect on VF test. XEN Gel Stent was implanted and IOP reduced to 10–14 mmHg without medical therapy. Optical coherence tomography angiography showed improvement in optic nerve head (ONH) perfusion density and flux, while the VF defect disappeared. Conclusion: Improvement in ONH perfusion and reversibility of early glaucomatous VF defect is feasible with prompt XEN Gel Stent implant in juvenile OHT.
... Reducing intraocular pressure (IOP) from glaucoma filtration surgery is accompanied by dynamic structural changes in the optic nerve head (ONH) [1][2][3][4][5][6][7][8][9][10][11][12]. These changes are called "reversal of disc cupping" because neuroretinal rim (NRR) tissue thickening is noted in funduscopic imaging and confocal scanning laser ophthalmoscopy [4,5,9,10,12]. ...
... These changes are called "reversal of disc cupping" because neuroretinal rim (NRR) tissue thickening is noted in funduscopic imaging and confocal scanning laser ophthalmoscopy [4,5,9,10,12]. Since optical coherence tomography (OCT) became available, several studies have been conducted on the detailed structural changes in the ONH and peripapillary retinal nerve fiber layer (RNFL) thickness after glaucoma filtration surgery [1][2][3]7,8,11]. Studies using OCT have found that the lamina cribrosa (LC) depth decreased after trabeculectomy, whereas the peripapillary RNFL thickness was unchanged [2,3,7]. ...
Purpose:
To investigate the factors associated with an increase in the neuroretinal rim (NRR) thickness measured based on Bruch's membrane opening-minimum rim width (BMO-MRW) after trabeculectomy in patients with primary open-angle glaucoma (POAG).
Methods:
We analyzed the BMO-MRW using spectral-domain optical coherence tomography (SD-OCT) of patients with POAG who underwent a trabeculectomy for uncontrolled intraocular pressure (IOP) despite maximal IOP reduction treatment. The BMO-MRW was measured before and after trabeculectomy in patients with POAG. Demographic and systemic factors, ocular factors, pre- and post-operative IOP, and visual field parameters were collected, together with SD-OCT measurements. A regression analysis was performed to investigate the factors that affected the change in the BMO-MRW after the trabeculectomy.
Results:
Forty-four eyes of 44 patients were included in the analysis. The IOP significantly decreased from a preoperative 27.0 mmHg to a postoperative 10.5 mmHg. The mean interval between the trabeculectomy and the date of post-operative SD-OCT measurement was 3.3 months. The global and sectoral BMO-MRW significantly increased after trabeculectomy, whereas the peripapillary retinal nerve fiber layer thickness did not show a difference between before and after the trabeculectomy. Younger age and a greater reduction in the IOP after the trabeculectomy were significantly associated with the increase in the BMO-MRW after trabeculectomy.
Conclusions:
The NRR thickness measured based on the BMO-MRW increased with decreasing IOP after trabeculectomy, and the increase in the BMO-MRW was associated with the young age of the patients and greater reduction in the IOP after trabeculectomy. Biomechanically, these suggest that the NRR comprises cells and substances that sensitively respond to changes in the IOP and age.
... Tanto la contribución vascular, como el estadio de la neuropatía, no fueron aspectos considerados en el presente estudio. (21,22,23) Aydin y otros (23) señalaron que después de la cirugía de catarata se produjo un incremento del espesor de la CFNR de 0,5 µm/mmHg, pero este resultado debe analizarse con cuidado, pues no se toma en consideración el papel del componente vascular en el incremento del espesor. De acuerdo con este estudio, después de la cirugía de catarata se produce un incremento del espesor de la capa de fibras. ...
... Tanto la contribución vascular, como el estadio de la neuropatía, no fueron aspectos considerados en el presente estudio. (21,22,23) Aydin y otros (23) señalaron que después de la cirugía de catarata se produjo un incremento del espesor de la CFNR de 0,5 µm/mmHg, pero este resultado debe analizarse con cuidado, pues no se toma en consideración el papel del componente vascular en el incremento del espesor. De acuerdo con este estudio, después de la cirugía de catarata se produce un incremento del espesor de la capa de fibras. ...
Objetivo:
Evaluar la modificación de la capa de fibras nerviosas después de la cirugía de catarata en pacientes con glaucoma primario de ángulo abierto.
Métodos:
Se realizó un estudio prexperimental en dos grupos de pacientes, 31 de ellos con glaucoma primario de ángulo abierto (49 ojos) y 29 pacientes sin glaucoma (50 ojos). Se analizó el comportamiento del espesor de la capa de fibras nerviosas retinianas antes y después de la cirugía de catarata (facoemulsificación). Fue evaluado el comportamiento pre y posoperatorio de la agudeza visual, así como la presión intraocular.
Resultados:
La edad promedio fue 71,8 ± 8,0 años en el grupo sin glaucoma y 67,8 ± 8,9 años en el grupo con glaucoma primario de ángulo abierto. La mediana de la agudeza visual sin corrección pasó de 0,20 a 0,90 en el grupo sin glaucoma y 0,30 a 0,80 en el grupo con glaucoma primario de ángulo abierto, donde resultó la p< 0,05 en ambos casos. La mediana de la presión intraocular cayó 1 mmHg en ambos grupos. En los cuadrantes superior e inferior hubo un incremento del espesor de la capa de fibras después de la operación en ambos grupos, pero solo se observó en cuadrantes nasal y temporal en el grupo con glaucoma.
Conclusiones:
Después de la cirugía de catarata se produce un incremento del espesor de la capa de fibras. La opacidad impide la transmisión de la señal a la retina.
... SD = standard deviation, IOP = intraocular pressure, RNFL = retinal nerve fibre layer, GCIPL = ganglion cell layer plus inner plexiform layer. differed 10,[13][14][15]17 . In subgroup analyses based on preoperative peak IOPs, there was significant RNFL thinning, and the higher the preoperative peak IOP, the greater the postoperative RNFL thinning in patients with a preoperative peak IOP ≥ 37 mmHg (median value). ...
... However, there was no meaningful change in RNFL thickness and no correlation was found between preoperative peak IOP and the extent of RNFL thinning in patients with a preoperative peak IOP < 37 mmHg. The mean preoperative IOPs in the studies by Aydin et al. 14 and Yamada et al. 13 were 22.0 ± 6.4 mmHg (38 eyes) and 22.6 ± 6.9 mmHg (46 eyes), respectively, even lower values than in our subgroup with a mean preoperative peak IOP < 37 mmHg (28.0 ± 4.9 mmHg in 30 eyes). The mean preoperative IOPs reported by Sarkar et al. 15 and Rebolleda et al. 17 were 26.9 ± 6.4 mmHg and 23.6 ± 5.1 mmHg, respectively. ...
Recent reports show varying results regarding peripapillary retinal nerve fibre layer (RNFL) thickness after intraocular pressure (IOP)-lowering glaucoma surgery. We hypothesised that different levels of the preoperative IOP influence RNFL thickness. A total of 60 patients (60 eyes) with glaucoma, who underwent glaucoma surgery and had a stable postoperative mean IOP < 22 mmHg, were enrolled. The RNFL thickness was measured using spectral domain optical coherence tomography, before and at 3–6 months after surgery. The preoperative peak IOP, 37.4 ± 10.8 mmHg, decreased to a postoperative mean IOP of 14.8 ± 3.5 mmHg (p < 0.001). The average RNFL thickness was significantly reduced from 75.6 ± 17.7 μm to 70.2 ± 15.8 μm (p < 0.001). In subgroup analyses, only patients with a preoperative peak IOP ≥ median value (37 mmHg) exhibited significant RNFL thinning (9.7 ± 6.6 μm, p < 0.001) associated with a higher preoperative peak IOP (r = 0.475, p = 0.008). The RNFL thinning was evident for a few months after glaucoma surgery in patients with a higher preoperative peak IOP, although the postoperative IOP was stable.
... Taking into account the contribution of LC deformation in glaucomatous optic neuropathy, it may be hypothesized that release of pressure on the nerve fibers passing through the LC should also result in changes in RNFL thickness after IOP reduction. While there are numerous studies reporting the increased [12][13][14] or unchanged [15][16][17] RNFL thickness measured with OCT following glaucoma surgery, longitudinal studies that considered the relationship between RNFL thickness and LC position postoperatively are scanty [9,10]. We have recently shown that the magnitude of LC displacement was associated with significant, focal RNFL thinning at six months post-operatively [18]. ...
... This is a longitudinal study that demonstrated the relationship between the LC position and RNFL thickness following glaucoma surgery. Although numerous studies evaluated the RNFL thickness after glaucoma surgery [12][13][14][15][16][17], reports on the rate of RNFL thickness loss and its relationship to the LC are scanty [9,10]. It has been reported that the LC could move anteriorly after glaucoma surgery [7][8][9][10]. ...
Purpose
To assess whether lamina cribrosa depth (LCD) reduction and the rate of change in LCD over time (ΔLCD/Δt) is associated with retinal nerve fiber layer (RNFL) thickness and the rate of RNFL thinning over time (ΔRNFL/Δt) to test the hypothesis that, in a long term, RNFL thinning occurs irrespectively to the displacement of the lamina cribrosa following glaucoma surgery.
Methods
Twenty-nine primary open-angle glaucoma patients underwent glaucoma surgery. Sixteen patients underwent trabeculectomy and 13 patients undertook non-penetrating deep sclerectomy. Images of optic nerve head using spectral-domain optical coherence tomography (SD-OCT) with enhanced depth imaging technology were obtained preoperatively, at one-, three-, six-month and follow-up postoperative visit from 12 to 29 months after surgery (1pv, 3pv, 6pv, and FUpv, respectively). Correspondingly, measurements of the circumpapillary RNFL thickness were acquired.
Results
Intraocular pressure decreased from 24.0±8.9 to 10.9±3.9mmHg at 6pv (P<0.001) and to 12.7±4.4mmHg at FUpv (P<0.001). LCD was reduced from 465.3±136.4μm to 402.9±126.4μm at 1pv (P<0.001) and maintained similar position at 6pv (394.3±118.4μm; P = 0.170 with respect to 1pv). A significant decrease in the LCD was noted at FUpv (342.8±90.3μm, P<0.001) with respect to 6pv. RNFL thickness increased significantly to 64.9±19.8μm at 1pv (P = 0.005) and subsequently decreased to baseline level at 3pv. Further statistically significant decrease in RNFL thickness with respect to previous visit was found at 6pv and at FUpv (56.4±15.6μm and 55.0±14.0μm, P = 0.023 and P = 0.045, respectively). A thinner RNFL thickness at FUpv was not related to the LCD at FUpv (P = 0.129) but was correlated with ΔLCD/Δt at FUpv (P = 0.003). The ΔRNFL/Δt at FUpv was statistically significantly correlated with ΔLCD/Δt at FUpv (P<0.001).
Conclusions
This is the first study that considers direct correlation between the rate of change in LCD with the rate of RNFL thinning over time. A thinner RNFL thickness following glaucoma surgery was associated with the rate of LCD reduction, not with position of the lamina cribrosa at the FUpv.
... Ali Aydin et al. 19 reported a statistically significant increase in mean RNFLT after trabeculectomy procedure (p <0.0001). The mean thickness increase in RNFL (0.5 µm / mm Hg IOP decrease) was much correlated with IOP reduction (r =-0.41; p =0.03). ...
Background: Glaucoma leads to changes in visual fields, optic nerve head (ONH) and retinal nerve fiber layer (RNFL). It is important to detect glaucomatous damage to avoid visual impairment and initiate treatment. Reversal of glaucomatous damage after intraocular pressure (IOP) lowering treatments has been reported in glaucoma patients. ONH and RNFL imaging by optical coherence tomography (OCT) are important to evaluate anatomical changes in glaucoma patients.
Objective: To assess the mean change in retinal nerve fiber layer thickness (RNFLT) on optical coherence tomography (OCT) in glaucoma patients after trabeculectomy. Methodology: A total of 30 patients of either gender undergoing trabeculectomy, having a duration of glaucoma >03 months, between the ages of 30-60 years were included. Patients having media opacity, or previous intraocular surgery and/or patients with history of trauma were excluded. After taking history, ophthalmic examination was carried out. OCT was done to measure the baseline and 03 months post-operative RNFLT.
Results: There were 63.3% males and 36.7% females, the mean age was 51.83±16.24 years, and the mean duration of disease was 16.50±10.46 months. Mean pre-operative and post-operative RNFLT was 48.56±9.46 µm and 58.03±16.81 µm respectively, and the mean RNFLT change after trabeculectomy was 24.43±18.61 µm which was statistically significant (p <0.004).
Conclusion: This study showed significant increase in RNFLT after trabeculectomy which is a good prognostic factor in the control of glaucoma.
... While the specific correlation between IOP and pulsatile deformation measured by OCT is not widely reported in the literature, there is growing evidence describing the remodeling of the ONH tissue in response to treatment [63,64] and in some cases it has been clinically described that RNFL thickness can improve after IOP has been stabilized [65,66]. Our method is a novel tool that, applied to a bigger cohort, could lead to deeper analysis on the correlation of biomechanics and positive outcomes to treatment in glaucoma. ...
This study investigated the effect of intraocular pressure (IOP) reduction on pulsatile displacement within the optic nerve head (ONH) in primary open-angle glaucoma (POAG) patients with and without axial myopia. Forty-one POAG patients (19 without myopia, 9 with axial myopia and 13 glaucoma with no intervention) participated. Swept-source optical coherence tomography (OCT) videos of the ONH were obtained before and after IOP-lowering treatment (medical or surgical) achieving a minimum IOP drop of 3 mmHg. A demons registration-based algorithm measured local pulsatile displacement maps within the ONH. Results demonstrated a significant 14% decrease in pulsatile tissue displacement in the non-myopic glaucoma cohort after intervention (p = 0.03). However, glaucoma patients with axial myopia exhibited no statistically significant change. There were no significant changes in the pulsatile ONH deformation in the control group. These findings suggest a potential link between IOP reduction and reduced pulsatile displacement within the ONH in POAG patients without myopia, offering new insights into the disease’s pathophysiology and warranting further investigation into underlying mechanisms and clinical implications.
... The mean RNFL thickness increase (0.5 μm/mmHg decrease of IOP) was significantly correlated with the IOP reduction (r=−0.41, P=0.03) [24]. ...
Objective The aim of this research was to study the effect of intraocular pressure (IOP) lowering after trabeculectomy on peripapillary blood flow and retinal nerve fiber layer (RNFL) thickness using optical coherence tomography angiography.
Study design This is a prospective, nonrandomized, single-center, observational study.
Patients and methods The study included 18 eyes of 18 patients with primary open angle glaucoma scheduled for trabeculectomy. Using optical coherence tomography angiography, the radial peripapillary vessel density (PVD) and RNFL thickness were quantified before and 1 week after surgery. Changes were calculated as total, superior hemi, and inferior hemi. They were then correlated with the change in IOP.
Results One week after surgery, the mean IOP reduction was −14.28±7.70 mmHg (−56.87±14.97%, P=0.000). The mean change in the radial PVD was +0.47±2.48% (P=0.431), and the mean change in RNFL thickness was +0.44±3.36 μm (P=0.582). There was no statistically significant correlation between these changes and the reduction in IOP (r=−0.104, P=0.682, and r=−0.287, P=0.249, respectively).
Conclusion There was a nonsignificant increase in the radial PVD and RNFL thickness after IOP reduction with trabeculectomy in primary open angle glaucoma, 1 week after surgery.
... Several studies have reported that the RNFL was thicker after IOP-lowering than before treatment. [33][34][35] The lower contrast and higher noise for the RNFL could therefore be explained by the thicker RNFL thickness after surgery, as this decreases the slope of the regression line (thereby reducing the contrast with the less severe glaucoma category) and increases the residuals (because the sudden change in thickness reduces the goodness-of-fit). Because, to the best of our knowledge, a similar effect of surgery on functional measurements has not been described, this could have affected the CNR outcomes and CNR differences between these different types of measurements. ...
Purpose:
To determine the sensitivity of optical coherence tomography (OCT) and standard automated perimetry (SAP) for detecting glaucomatous progression in the superior and inferior hemiretina.
Methods:
We calculated contrast-to-noise ratios (CNRs) for OCT retinal nerve fiber layer (RNFL) thickness of hemiretinas and for SAP mean total deviation (MTD) of the corresponding hemifields from longitudinal data (205 eyes, 125 participants). The glaucoma stage for each hemiretina was based on the corresponding hemifield's MTD. Contrast was defined as the difference of the parameter between two consecutive glaucoma stages, whereas noise was the measurement variability of the parameter in those stages. The higher the CNR of a parameter, the more sensitive it is to detecting progression in the transition between successive stages.
Results:
There were no statistically significant differences for the RNFL CNR and MTD CNR between superior and inferior hemiretinas. As the glaucoma stage of the opposite hemiretina worsened, the MTD CNR in the transition from moderate to advanced glaucoma significantly increased. The RNFL CNR in the transition from mild to moderate glaucoma significantly decreased in case of advanced glaucoma in the opposite hemiretina.
Conclusions:
Similar to full retinas, detecting conversion to glaucoma in hemiretinas is more sensitive with OCT than SAP, whereas with more advanced disease, SAP is more sensitive for detecting progression. More importantly, the sensitivity for detecting progression in one hemiretina with either technique depends on the glaucoma severity in the opposite hemiretina.
Translational relevance:
Monitoring glaucomatous progression with either OCT or SAP partly depends on the glaucoma severity in the opposite hemiretina.
... In our study, no significant changes were found in the inferior, superior, nasal and temporal RNFLT measurements. In the literature, there are different publications reporting no change or an increase in RNFLT after IOP-lowering medical or surgical treatment [26,27]. In the postoperative period of our study, there was no significant change in mean cup / optic ratios in the RNFL analysis. ...
Purpose:
To evaluate the effects of lowering intraocular pressure (IOP) on foveal avascular zone (FAZ), peripapillary and macular vessel density (VD) by optical coherence tomography angiography (OCTA) in patients with open angle glaucoma after trabeculectomy.
Study design:
Prospective study METHODS: Twenty eyes of 20 patients with primary open angle glaucoma (POAG) or exfoliation glaucoma (EG) who were followed up to six months and underwent trabeculectomy were included in our study. OCTA, AngioVue (Optovue Inc.) software was used to analyse the FAZ, peripapillary VD, macular superficial capillary plexus (SCP) and deep capillary plexus (DCP) VD. The parameters of the preoperative and postoperative controls were compared statistically.
Results:
Twelve of the patients (60%) had POAG and eight (40%) had EG. Mean IOP measured was 22.4±2.4 mmHg preoperatively and 14.9±2.4 mmHg in the postoperative sixth month (p <0.001). There were no significant changes in OCTA optic disc and macular SCP VD values at the end of the sixth month. In macular DCP parameters; whole image VD (WI-VD), foveal VD (F-VD), parafoveal VD (PAF-VD) and perifoveal VD (PEF-VD) values increased statistically (p=0.003; p=0.026; p=0.006; p=0.004). There was a statistically significant decrease in FAZ area (FAZ-A) and FAZ perimeter (FAZ-P); and a significant increase was found in foveal density values (FD) (p=0.026; p=0.049; p=0.005).
Conclusions:
We found that reducing IOP by trabeculectomy did not affect the microcirculation of the peripapillary region and macular SCP, while there was a significant increase in the DCP parameters of the macular region.
... [23] Increased RNFL thickness after IOP reduction either medically or surgically is thought to be due to the reversal of the physical compressive effect on the RNFL by the high IOP. [24] IOP reduction leads to a recovery of normal shape and size of the retinal ganglion cell axons with subsequent increase in RNFL thickness. Furthermore, hyptony after IOP reduction, especially after surgery may cause retinal and disc swelling with increased RNFL thickness. ...
Purpose
The purpose is to compare the changes in the peripapillary blood flow in primary open-angle glaucoma (POAG) after administration of dorzolamide 2%/timolol 0.5% fixed combination versus latanoprost 0.005%/timolol 0.5% fixed combination, using spectral-domain optical coherence tomography angiography (OCTA).
Patients and Methods
In this prospective, comparative, nonrandomized study, patients with POAG received simultaneous treatment with dorzolamide 2%/timolol 0.5% fixed combination in the right eye (Group 1) and latanoprost 0.005%/timolol 0.5% fixed combination in the left eye (Group 2) for 1 week. Intraocular pressure (IOP) was measured using applanation tonometry; and peripapillary capillary density and retinal nerve fiber layer (RNFL) thickness was assessed using OCTA before starting treatment and 1 week after the treatment.
Results
IOP reduction was superior in Group 2; however, this was not statistically significant. Both groups showed an increase in the peripapillary capillary density and RNFL thickness after 1 week of the treatment as evaluated by OCTA angiography. However, this increase was not statistically significant. There was only a statistically positive correlation between IOP reduction and increase in the superior-hemiradial peripapillary capillary density ( P = 0.037) in Group 1 and between IOP reduction and increase in the total RNFL thickness and superior hemi-RNFL thickness ( P = 0.044, 0.032, respectively) in Group 1.
Conclusion
Intraocular pressure decreased in both groups with no significant difference between both groups. There was more increase in radical peripapillary capillary density and RNFL thickness following treatment in dorzolamide 2%/timolol 0.5% group compared to the other groups; however, the difference between the two groups was not statistically significant.
... Some studies reported a reversal in disc cupping [18]. Others have demonstrated significant decreases in cup depth following trabeculectomy [19] as well as increase in RNFL thickness measurements [20]. Additionally, improvement of ocular surface health following the reduction of IOP-lowering medication use with successful surgical IOP control may contribute to improvement of BCVA. ...
Purpose To compare trabeculectomy with Ologen implant(Trab-Ologen) to combined viscotrabeculo-tomy-synechiolysis(VTS) in uncontrolled uveitic glaucoma (UG). Patients and methods A retrospective chart review of 47 patients subjected to VTS(24 eyes) or Trab-ologen(23 eyes) at Mansoura Ophthalmic Center between 2010 and 2016. The patients were evaluated on day 1, week 1, months 1, 3, 6, 12, 18, 24, 30, 36, 42, and 48. Results The mean ± standard deviation age of patients in the Trab-ologen and VST groups were 38.29 ± 12.5 and 38.91 ± 11.8 years (p = 0.86), respectively. Juvenile Idiopathic arthritis (controlled on methotrexate) was the most common associated systemic disease (3 patients in each group). The mean ± standard deviation of the intraocular pressure (IOP) and IOP-lowering medications preoperatively and at the end of follow up in the Trab-ologen and VST groups were 33.1 ± 2.6 mmHg, 33.2 ± 2.6 mmHg (p = 0.91), 3.4 ± 0.5, 3.4 ± 0.5 (0.90) and 15.4 ± 1.2 mmHg, 13.0 ± 0.9 mmHg (p \ 0.001), 0.6 ± 1.1, 0.7 ± 1.2 (p = 0.72), respectively. IOP control was better in the Trab-ologen group till the 30th month when it becomes better in the VST group till the end of follow-up. The most notable complication was a minimal self-limiting hyphema in the VST group. Success rates at the end of follow-up in the Trab-ologen and VST groups were 83% and 78%, respectively. Conclusions Trabeculectomy with ologen implant and visco-trabeculotomy-synechiolysis were equally effective in lowering IOP in uncontrolled UG. There was no statistically significant difference in the success rates between the 2 procedures.
... Some studies reported a reversal in disc cupping [18]. Others have demonstrated significant decreases in cup depth following trabeculectomy [19] as well as increase in RNFL thickness measurements [20]. Additionally, improvement of ocular surface health following the reduction of IOP-lowering medication use with successful surgical IOP control may contribute to improvement of BCVA. ...
PurposeTo compare trabeculectomy with Ologen implant(Trab-Ologen) to combined viscotrabeculotomy-synechiolysis(VTS) in uncontrolled uveitic glaucoma (UG).
Patients and methodsA retrospective chart review of 47 patients subjected to VTS(24 eyes) or Trab-ologen(23 eyes) at Mansoura Ophthalmic Center between 2010 and 2016. The patients were evaluated on day 1, week 1, months 1, 3, 6, 12, 18, 24, 30, 36, 42, and 48.ResultsThe mean ± standard deviation age of patients in the Trab-ologen and VST groups were 38.29 ± 12.5 and 38.91 ± 11.8 years (p = 0.86), respectively. Juvenile Idiopathic arthritis (controlled on methotrexate) was the most common associated systemic disease (3 patients in each group). The mean ± standard deviation of the intraocular pressure (IOP) and IOP-lowering medications preoperatively and at the end of follow up in the Trab-ologen and VST groups were 33.1 ± 2.6 mmHg, 33.2 ± 2.6 mmHg (p = 0.91), 3.4 ± 0.5, 3.4 ± 0.5 (0.90) and 15.4 ± 1.2 mmHg, 13.0 ± 0.9 mmHg (p < 0.001), 0.6 ± 1.1, 0.7 ± 1.2 (p = 0.72), respectively. IOP control was better in the Trab-ologen group till the 30th month when it becomes better in the VST group till the end of follow-up. The most notable complication was a minimal self-limiting hyphema in the VST group. Success rates at the end of follow-up in the Trab-ologen and VST groups were 83% and 78%, respectively.Conclusions
Trabeculectomy with ologen implant and visco-trabeculotomy-synechiolysis were equally effective in lowering IOP in uncontrolled UG. There was no statistically significant difference in the success rates between the 2 procedures.
... 7,8 The most common postoperative complication associated with visual loss is represented by pseudophakic cystoid macular edema. [9][10][11][12][13] While several studies have focused on retinal abnormalities, 12,14,15 few authors have investigated the choroidal trend in patients undergoing cataract surgery. Recently, using mouse models following cataract extraction, the authors have found an increased expression of the proinflammatory gene and protein secretion in both retinal and choroidal tissue. ...
Purpose
To report potential choroidal changes in eyes undergoing femtosecond laser cataract surgery (FLACS) and phacoemulsification surgery (PCS) by OCT.
Methods
The patients were images by means Spectral Domain OCT imaging with EDI technology which may obtain OCT image. We exported a single EDI-OCT scan passing through the fovea and then it was imported into ImageJ program to perform a quantitative analysis.
Main outcome measures
The main outcome measures were: (i) sub foveal choroidal thickness (SFCT); (ii) the choroidal vascularity index (CVI); and (iii) central retinal thickness (CRT).
Results
At postoperative 1 week, FLACS group showed an increased CRT (241.2 ± 31.6–245.5 ± 36.4 µm; p = 0.016). Likewise, CVI and SFCT exhibited a slight increase but no statistically differences were highlighted (p > 0.05). At the follow-up visit of 1 month, all OCT parameters did not display any significant difference (p > 0.05). At post-operative 1 week, the PCS group displayed a significant increase in CRT, SFCT, and CVI. On the contrary, at the follow-up visit of 1-month, all choroidal parameters were characterized by a no statistically significant reduction (p > 0.05).
Conclusions
Our study exhibited a significant increase in CT and CVI in eyes that underwent conventional cataract surgery. Femtosecond laser-assisted cataract extraction did not result in macular change due to less postoperative inflammation.
... Aydin et al were able to show a postoperative increase in RNFL using a prototype OCT. 38 Other studies confirmed this finding by using a scanning laser polarimetry. 39 On the contrary, different studies indicated no significant RNFL alterations after surgery. ...
Purpose
Lowering the intraocular pressure (IOP) in patients with primary open-angle glaucoma (POAG) with filtration surgery can induce morphological changes to the bulbus and structures of the retina. In this study, we have evaluated changes of Bruch’s membrane-based parameters and retinal nerve fiber layer (RNFL) derived by spectral-domain optical coherence tomography (SD-OCT) in eyes that have undergone glaucoma filtration surgery.
Patients and Methods
SD-OCT imaging of the optic nerve head (ONH) and of the RNFL was performed in 54 eyes of 54 patients with medically uncontrolled POAG before and after IOP-lowering surgery (trabeculectomy or deep sclerectomy). The ONH parameter minimum rim width (MRW) and the size of the Bruch’s membrane opening (BMO-Area) were derived from 24 radial B-scans centered on the ONH.
Results
The average preoperative IOP was 23.1 ± 7.5 mmHg. One month postoperatively, the average IOP decreased to 12.1 ± 4.6 mmHg (p < 0.01), which caused a significant increase in the thickness of neuroretinal rim. There was no significant change in the automatically detected BMO-Area (p = 0.32). The pressure-related increase in MRW correlated well with the postoperative IOP and cup-to-disc ratio (CDR). In regression analysis, the alteration in thickness of the neuroretinal rim could be well predicted in a model including CDR, change of IOP and mean deviation (MD) (R² = 0.414, p < 0.001). RNFL showed a significant increase as well.
Conclusion
IOP-lowering surgery in patients with medically uncontrolled POAG causes an increased thickness of the SD-OCT derived ONH parameters. The changes of the RNFL after surgery showed no significant correlations with IOP changes. In contrast to this, highly significant correlations of MRW values with the IOP could be observed. The BMO-Area remained completely stable A preferred use of RNFL for follow-up should be discussed.
... Reports indicated the structural modifications in ocular parameters such as axial length (AL) size [7], optic nerve head shape [8][9][10][11], lamina cribrosa curvature [10][11][12][13], choroid thickness [8], peripapillary retinal nerve fiber layer (RNFL) thickness [10,[14][15][16][17][18][19][20], macular thickness [1,18,19,[21][22][23][24][25][26] and retinal vessel density [19,[27][28][29] following the acute decrement in IOP after performing the glaucoma filtration surgery. However, a small number of studies included an assessment of the central retinal modifications following trabeculectomy, particularly those relating to the utilization of antifibrotic agents. ...
PurposeThe aim of this study is to compare, using optical coherence tomography (OCT), the changes in the thickness of the macular nerve fiber layer (mNFL), macular ganglion cell layer (mGCL), macular inner plexiform layer (mIPL) and peripapillary global retinal nerve fiber layer (gRNFL) (in a span of 3 years) in surgically treated eyes with primary open-angle glaucoma (POAG).Methods
The medical records of 32 consecutive POAG patients who underwent trabeculectomy with mitomycin-C, between January 2013 and December 2014, were retrospectively reviewed. Pre- and postoperative measurements of IOP and OCT were analyzed 1, 2 and 3 years after the operation.ResultsAmong all patients, no significant changes in the thickness of the mNFL, mGCL or mIPL were found, with a significant reduction observed only in the IOP values and peripapillary gRNFL thickness during the 3-year postoperative period. In a subgroup analysis based on the preoperative peak IOPs (median value:41 mmHg), the thickness of the mNFL, mGCL and mIPL in the 3-year postoperative period increased significantly in the lower preoperative peak IOP group (IOP < 41 mmHg), whereas the macular OCT parameters in the 3-year postoperative period decreased in the higher preoperative peak IOP group.Conclusions
Eyes exhibiting lesser preoperative peak IOP demonstrated greater preservation of the layer-by-layer segmented macular ganglion cell complex thickness as compared to eyes exhibiting greater preoperative peak IOP; also when the IOPs determined for the two groups in the period of follow-up were quite comparable.
... This was consistent with the growing evidence of slight reversal of structural glaucomatous damage after controlling the IOP [18] . Some studies reported improvements in structural measurements following effective reduction in IOP with glaucoma surgery as a reversal in disc cupping or significant decreases in cup depth as well as increase in RNFL thickness measurements [19][20][21] . Additionally, the improvement of ocular surface health following the reduction of IOP-lowering medication use together with the successful surgical IOP control may contribute to improvement of BCVA. ...
● AIM: To evaluate the safety and efficacy of augmented
trabeculotomy with Ologen versus perfluoropropane in
management of pseudophakic glaucoma.
● METHODS: This is a comparative randomized study
included 57 pseudophakic eyes of 57 patients with
medically uncontrolled open angle glaucoma (OAG). Twentynine
patients were allocated in group I (trabeculectomy with
Ologen; trab-ologen group), while 28 patients were assigned
in group II (trabeculectomy with perfluoropropane gas
bubble; trab-C3F8 gas bubble group).
● RESULTS: The intraocular pressure (IOP) was significantly
reduced in both study groups at all postoperative follow up
intervals (1wk, 3, 6, 12, 18, 24, 30 and 36mo, P<0.001).
The differences between the mean IOP values of both groups
remained statistically insignificance during the early 12 months
of follow up. However, the trab-ologen group achieved a
statistically significant reduction over the trab-C3F8 gas
bubble group during the last 24 months of follow up.
● CONCLUSION: Augmentation of trabeculectomy with
either Ologen implant or perfluoropropane gas bubble are
associated with strict long term IOP control and evident safety
in medically-uncontrolled pseudophakic eyes with OAG.
... Hence, one of the main reasons for an perceptible improvement in optic nerve appearance with IOP reduction is a reduction in the posterior bowing of the LC, giving relief to the compressed nerve fiber bundles. [5][6][7][8][9] The patients included in our study had age range older than 40 years and not more than 80 years [ Table 1]. The mean age was found to be 57.9 years. ...
... Ali Aydin et al. 21 showed the mean MD and PSD of the preoperative visual field were −11.3 ± 9.2 dB and 8.2 ± 4.2 dB, respectively and the mean MD and PSD of postoperative visual field were −10.6 ± 8.1 dB and 7.8 ± 4.5 dB, respectively. These differences were not statistically significant (P = 0.43 and P = 0.34, respectively). ...
The study was conducted to find out the topographic changes of disc, macular thickness, visual field, and intra-ocular pressure (IOP) after trabeculectomy in different age and sex using Optical Coherence Tomography (OCT) machine, automated perimeter and Goldman applanation tonometer respectively.
It was a prospective, interventional case-series conducted at the glaucoma clinic at Regional Institute of Ophthalmology, Kolkata from March 2010 to August 2011. Patients of primary open angle glaucoma who fulfilled the inclusion criteria. The trabeculectomy surgeries were done by a single surgeon. The disc changes, macular thickness, IOP and visual field changes were measured before and after trabeculectomy. Preoperative OCT images of disc and macula, visual field testing by Humphrey automated perimeter and IOP by Goldman applanation tonometry were done/within 3 months prior to surgery and same investigations had been done postoperatively within 2 to 3 months after surgery. Data was collected in a standard data collection form and analysis was done by paired t-test.
Significant visual field (mean deviation-MD & pattern standard deviation-PSD in decibel) changes were seen but the nerve fiber thickness in the disc and macula were not increased. Significant reduction of IOP was found after trabeculectomy.
Significant visual field (MD& PSD) changes were found after trabeculectomy in early glaucoma patients but disc and macular changes were found to be insignificant.
... Barring complications, whereas control of IOP is relatively successful, the effect on VF outcomes remains largely divided in studies, with some showing significant changes, 20,21 whereas others do not. 22,23 The question of VF outcome is further compounded by the variability of SAP, learning effects, and regression to the mean. Although structural changes could theoretically provide an indication of VF changes through the structure-function relationship, the relationship between structure and function is nonuniform throughout the retina, with contrast sensitivity drop-off varying with eccentricity 24,25 and physiological variations in the cpRNFL thickness around the optic nerve head. ...
Precis:
Improvements in post-trabeculectomy visual field outcomes were found to be significantly associated with pre-operative nerve fiber layer thickness parameters extracted from the sectorized structure-function relationship, baseline visual field and severity of glaucoma.
Objective:
To determine whether the pre-operative structure-function relationship helps to predict visual outcomes at one-year post-trabeculectomy.
Patients and methods:
91 eyes from 87 participants who successfully underwent trabeculectomy were included in our study. All eyes received optical coherence tomography imaging and visual field assessment using 30-2 standard automated perimetry pre-operatively at baseline and post-operatively one year after trabeculectomy. Linear mixed model analysis was used to assess the association of structure and function at baseline, and multivariate analysis to investigate factors associated with post-operative visual field outcomes.
Results:
Results from multivariate and univariate analysis for visual field one year after trabeculectomy showed that a positive pre-operative retinal nerve fiber layer thickness deviation from the structure-function model was found to be significantly associated with improved post-operative visual field outcomes (β=0.06▒dB/μm; 95% CI, 0.03 to 0.09). Other significant factors included baseline visual field mean deviation (β=-0.18; 95% CI -0.23 to -0.13) and the presence of severe glaucoma (β=-1.69; 95% CI, -2.80 to -0.57). Intraocular pressure was positively associated with improved visual field outcomes only in univariate analysis (β=0.06; 95% CI, 0.01 to 0.11).
Conclusions and relevance:
Characteristics derived from the baseline structure-function relationship were found to be strongly associated with post-operative visual field outcomes. These findings suggest that the structure-function relationship could potentially have a role in predicting visual field progression after trabeculectomy.
... In the Collaborative Initial Glaucoma Treatment Study (CIGTS), VF worsening was significantly associated with enlargement of the optic cup, but reversal of cupping was not associated with improvement of the VF 12 . Other studies reported an early increase in retinal nerve fiber layer (RNFL) thickness after trabeculectomy, but did not investigate the relation with VF changes [13][14][15][16][17] . Also, these studies have used the older time-domain optical coherence tomography (OCT) 14,16 , stereoscopic optic disc photographs 12,15 scanning laser polarimetry 17 , or Heidelberg Retina Tomography (HRT) 11,13 , which required a manually drawn contour line and thus was more prone to operator induced variability than the newer spectral-domain OCT. ...
We evaluated the changes in visual field mean deviation (VF MD) and retinal nerve fibre layer (RNFL) thickness in glaucoma patients undergoing trabeculectomy. One hundred patients were examined with VF and spectral-domain optical coherence tomography (OCT) before trabeculectomy and 4 follow-up visits over one year. Linear mixed models were used to investigate factors associated with VF and RNFL. VF improved during the first 3 months of follow-up (2.55 ± 1.06 dB/year) and worsened at later visits (−1.14 ± 0.29 dB/year). RNFL thickness reduced by −4.21 ± 0.25 µm/year from 1st month of follow-up. Eyes with an absence of initial VF improvement (β = 0.64; 0.30–0.98), RNFL thinning (β = 0.15; 0.08–0.23), increasing intraocular pressure (IOP; β = −0.11; −0.18 to −0.03) and severe glaucoma (β = −10.82; −13.61 to −8.02) were associated with VF deterioration. Eyes with VF deterioration (β = 0.19; 0.08–0.29), increasing IOP (β = −0.09; −0.17 to −0.01), and moderate (β = −6.33; −12.17 to −0.49) or severe glaucoma (β = −19.58; −24.63 to −14.52) were associated with RNFL thinning. Changes in RNFL structure and function occur over a 1-year follow-up period after trabeculectomy. Early VF improvement is more likely to occur in patients with mild/moderate glaucoma, whereas those with severe glaucoma show greater decline over one year. Our findings indicate that progression is observable using OCT, even in late-stage glaucoma.
... Aydin et al (9) used a non-commercial, prototype OCT device to evaluate RNFL thickness change following trabeculectomy, and reported a significant increase. The differences were more marked in the group that had the cataract surgery also. ...
... 16 Aydin and associates studied the changes in thickness of the retinal nerve fiber layer after filteration surgery. 18 An increase of 0.5 m in thickness of retinal nerve fiber layer for every 1 mm of Hg reduction in the intraocular pressure was observed. Hence, it was inferred that 30% reduction in the intraocular pressure, as a result of trabeculectomy, leads to increased thickness of the retinal nerve fiber layer. ...
Objective: To determine the changes in the retinal nerve fiber layer as measured on optical coherence tomography (OCT) after phacoemulsification with intraocular lens implantation. Study Design: Quasi-experimental study. Place and Duration of Study: Department of Ophthalmology, Lahore General Hospital, Lahore, from March 2017 to April 2018. Methodology: All patients (n=64) diagnosed with cataract and requiring surgery were included in study. Patients having any coexisting ocular pathology hindering the OCT measurement, i.e. corneal opacity, vitreous hemorrhage, retinal detachment etc. were excluded from study. Retinal nerve fiber layer thickness was measured in four quadrants. Signal strength on OCT was also documented. Preoperatively, visual acuity was measured, OCT performed, and the findings were recorded on a designed proforma. Postoperatively, the patients followed up after one month for visual acuity and OCT measurement. Results: Retinal nerve fiber layer thickness was increased postoperatively as measured on OCT as did the signal strength. The increase was statistically significant (p<0.001). Conclusion: Removal of cataract by surgery enhances the OCT measurement of retinal nerve fiber layer, resulting in increased thickness. © 2018 College of Physicians and Surgeons Pakistan. All rights reserved.
... Structural reversibility after glaucoma treatment is well documented. Reversible optic disc cupping following acute IOP lowering has been known to occur for decades [16][17][18][19][20][21]. Quigley [16] described an improvement of the optic disc cupping appearance in 40% of children with successful IOP lowering after trabeculectomy. ...
Purpose
To evaluate the microvascular changes at the peripapillary area and optic disc in glaucomatous eyes after IOP lowering by trabeculectomy using OCT angiography.
Methods
25 patients with primary open-angle glaucoma (POAG) who underwent trabeculectomy by a single surgeon were evaluated. Using optical coherence tomography angiography, vessel density was evaluated within the whole image, peripapillary, nasal region, and temporal region. Peripapillary vessel density was measured preoperative, 1 week, 1 month, and 3 months postoperatively in POAG patients. Reversal of vessel density was calculated for all analyzed areas.
Results
The intraocular pressure (IOP) decreased from 30.92 ± 6.32 mmHg (range, 18–44) to 12.64 ± 3.35 mmHg (range, 8–22) at 3-month postoperatively. Compared with the preoperative baseline value, whole vessel density, peripapillary vessel density (PvD), and PvD in nasal region and temporal region were significantly increased at 3-month postoperatively. The magnitude of the vessel density reversal was significantly associated with higher preoperative IOP and greater IOP reduction.
Conclusions
A significant increase in the peripapillary vessel density was demonstrated after trabeculectomy using OCT angiography. The reversal of peripapillary vessel density was associated with higher preoperative IOP and greater IOP reduction. Our postoperative results suggest that the ocular perfusion impairment by high intraocular pressure can be improved by IOP reduction, and the reversal of microvasculature may contribute to the rate of glaucoma progression.
... Harwerth model was derived from a much larger number of eyes, but from an animal model, with results extrapolated to humans (Harwerth et al 2010 Changes in RNFL thickness can also be caused by RGC shrinkage rather than frank loss of cells (Morgan 2002) and the RNFL may increase in thickness with surgical reduction of IOP (Aydin et al 2003). Agreement between structure and functional domains will also be affected by It is also important to acknowledge that although structure function models strive to explain the relationship between glaucomatous structural changes and changes to visual function, there is unlikely to be a perfect relationship between structure and function. ...
BACKGROUND: Imaging is widely used to quantify glaucomatous structural changes. Although previous studies have examined the relationship between structure and function, measured using standard automated perimetry (SAP), the true relevance of structural changes remains poorly understood. AIM: The aim of this body of work was to explore the structure-function relationship and to ascertain the point at which structural changes become associated with impaired ability to perform vision-dependent tasks. PLAN OF RESEARCH: After critically appraising previously described structurefunction models, an investigation was conducted progressively evaluating the relationship between glaucomatous structural changes and 1) estimated loss of retinal ganglion cells (RGCs), 2) an objective measure of visual function (the pupil response), and 3) a vision-related task relevant to quality of life (driving). RESULTS: Localised RNFL defects visible on photographs, a common manifestation of glaucoma, were associated with large estimated RGC losses. However, problems were identified with the published method of RGC estimation. Asymmetric RNFL thinning was also found to be associated with asymmetry of the pupil response, and the magnitude of asymmetry required for a clinically detectable relative afferent pupillary defect (RAPD) was calculated. Finally, loss of RNFL was associated with worse ability to perform a simulated driving task, providing additional information to SAP alone. SIGNIFICANCE: Glaucomatous structural defects may be associated with significant functional impairment. Incorporating information from both structure and function may improve our ability to predict patients at risk of developing problems with vision-related tasks of daily living.
... Sectoral thinning of the RNFL thickness occurs with glaucoma progression. Several studies using stereovideo image analysis (Sogano et al., 1993), scanning laser polarimetry (Yamada et al., 2000) and OCT (Aydin et al., 2003;Raghu et al., 2012) have reported increases in RNFL thickness initially following glaucoma surgery, however this effect is thought to be transient (Figus et al., 2011;Raghu et al., 2012;Sogano et al., 1993). Most studies using CSLO have not demonstrated any significant RNFL changes following IOP lowering (Bowd et al., 2000;Irak et al., 1996;Lesk et al., 1999). ...
Retinal ganglion cell (RGC) degeneration causes vision loss in patients with glaucoma, and this has been generally considered to be irreversible due to RGC death. We question this assertion and summarise accumulating evidence that points to visual function improving in glaucoma patients with treatment, particularly in the early stages of disease. We propose that prior to death, RGCs enter periods of dysfunction but can recover with relief of RGC stress. We first summarise the clinical evidence for vision improvement in glaucoma and then detail our experimental work that points to the underlying processes that underpin clinical improvement. We show that functional recovery can occur following a prolonged course of RGC dysfunction and demonstrate how the capacity for recovery can be modified. Detecting RGC dysfunction and augmenting recovery of such 'comatosed' RGCs holds clinical potential to improve early detection of glaucoma and improve visual function.
... 31 of 38 eyes had an increase in RNFL thickness at 6-12 months following surgery, with a mean increase of 12.6 μm. 20 In fact there is a considerable body of evidence demonstrating reversal of structural glaucomatous damage following pressurelowering surgical interventions, with apparent reversal of structural changes especially common in younger patients with congenital, infantile and juvenile-onset glaucoma. [21][22][23][24][25] In contrast to the improvements observed in structural measurements, evidence for functional improvement following glaucoma surgery is scarce. ...
Purpose: Glaucoma is a progressive optic neuropathy and a leading cause of blindness. Neural losses from
glaucoma are irreversible, and so the aim of glaucoma treatment is to slow progression and minimize the risk of
further damage. Visual loss post filtration surgery in patients with advanced glaucomatous optic nerve damage is
a rare but dreaded complication. Functional improvement is not expected. We report the case of a patient who
experienced a significant loss of vision following glaucoma surgery that was followed by late visual recovery. We
will also review the literature regarding this phenomenon.
Case presentation/Observations: A 60-year old male presented with a history of right pseudoexfoliative glaucoma
and uncontrolled intraocular pressure(IOP) on medical and laser treatment. He underwent a successful right
Mitomycin C augmented trabeculectomy combined with phacoemulsification. Unexpectedly, he experienced a
marked decrease in vision from 0.3 to hand motion with no identifiable explanation. The loss of vision continued
for almost 4 months before a significant improvement in vision occurred and his visual acuity came up to 0.6.
Although the mechanism of loss or improved vision cannot be proven, it is likely that post operative IOP spikes
which were repeatedly above 30 mmHg in the first week, resulted in ganglion cell dysfunction rather than
apoptosis which can explain the improvement in vision in the later months when pressure was maintained at
target.
Conclusion: and Importance: Although rare, Wipe out phenomenon is possible in the setting of advanced glaucomatous
optic neuropathy. However, functional improvements may occur following IOP control. Glaucoma
surgery should be offered early to those with advanced disease.
... In contrast to the current results, Aydin et al. [18] used a noncommercial, prototype OCT device to evaluate RNFL thickness change following trabeculectomy, and reported a significant increase in overall RNFL thickness and showed a significant correlation between RNFL thickness and extent of IOP reduction. ...
Purpose The aim of this study was to evaluate the ability of optical coherence tomography (OCT) to detect the changes in retinal nerve fiber layer (RNFL) after reaching target intraocular pressure (IOP) in glaucomatous patients.
Patients and methods Thirty-two (58 eyes) patients with a clinical diagnosis of primary open-angle glaucoma were assessed as regards peripapillary RNFL thickness and optic nerve head parameters by 3D-OCT for a follow-up period of 6 months. The drugs used to reach target IOP were Twinzol (dorzolamide 2%/timolol 0.5%) eye drops 5 ml and Ioprost (Latanoprost) 0.005% (50 mcg/ml) eye drops 3 ml. Eleven patients were treated with Twinzol only and reached target IOP after adding Ioprost. Eight patients were treated with Ioprost only and reached target IOP after adding Twinzol, and 13 patients had no added treatment, where four reached target IOP by Ioprost only, six reached target IOP by Twinzol only, and three reached target IOP by both drugs. OCT was done for all patients after achieving target IOP and was repeated after 6 months of medical control.
Results The mean IOP before treatment was 29.89 mmHg and decreased significantly (P
... Additionally, an IOP lowering leads to the reduction of the retinal interstitial pressure and an increase in the gradient of the capillary/intercellular pressure leading to enhanced filtration and fluid accumulation in the intracellular retinal space (8,22). It has been suggested that the thickening of the retinal nerve fibre layer observed after glaucoma filtration surgery is due to a parapapillary swelling (23). Finally, inflammation may play a role in the thickening of the retina, because the inflammatory mediators from the anterior chamber are reported to reach the posterior pole of the eye and increase the permeability of the blood-aqueous barrier associated with vascular leakage (24)(25)(26). ...
Conflict of interest:
None of the authors have any conflict of interest to declare, financial or otherwise. No financial or other support was received for the study.
Background:
The aim of the study was to assess changes in macular thickness after trabeculectomy in respect to the use of 5-fluorouracil (5-FU) as well as to analyse possible associations between the postoperative changes in macular thickness and intraocular pressure (IOP).
Materials and methods:
The prospective observational study included 106 eyes (100 patients) with glaucoma who underwent trabeculectomy with or without 5-FU. Subsequently 5-FU needling was performed if failure of the filtrating bleb occurred. Macular thickness and the IOP were evaluated before, one week, and six months after the surgery. The mean and sectoral macular thickness was assessed using spectral domain optical coherence tomography.
Results:
The mean (±SD) IOP reduced from 27.71 (±6.88) mmHg at baseline to 18.3 (±8.1) mmHg one week (p < 0.001) and 15.1 (±7.6) mmHg six months (p < 0.001) after trabeculectomy. One week postoperatively, the mean macular thickness increased from 285.19 (±15.98) μm to 288.9 (±16.31) μm (p < 0.001); macular thickening was significant in all subfields (p < 0.001) and correlated positively with IOP reduction (rho = 0.312, p = 0.001 for central subfield). After six months, macula remained thicker only at the central and inner nasal subfields (p < 0.05). The changes in macular thickness were not affected by the use of 5-fluorouracil.
Conclusions:
Trabeculectomy may induce a slight macular thickening which is more pronounced in the early postoperative period. The IOP reduction plays an important role in this process and is associated with thicker postoperative macula. However, the use of adjunctive 5-FU has no influence on macular thickness after glaucoma surgery despite its potential hypotonic, inflammatory and cytotoxic effects.
... Variations depend on the presence of vessels and their glial envelope, characterized by its porous nature and the ability to carry fluid (40). The presence of fluid in the preliminar tissue both in the capillary net and in the glial envelope can account for the swift variations in the thickness of the NFL after surgery (47). New measurements are currently being introduced to estimate NFL thickness by the distance between the end of the Bruch membrane and the Elschnig limit that would more strictly correlate with the thickness of the central neuroretinal rim of the central cup (48). ...
Background: To settle the fundamentals of a numerical procedure that relates retinal ganglion-cell density
and threshold sensitivity in the visual field. The sensitivity of a generated retina and visual pathways to virtual
stimuli are simulated, and the conditions required to reproduce glaucoma-type defects both in the opticnerve
head (ONH) and visual fields are explored.
Methods: A definition of selected structural elements of the optic pathways is a requisite to a translation
of clinical knowledge to computer programs for visual field exploration. The program is able to generate
a database of normalized visual fields. The relationship between the number of extant receptive fields and
threshold sensitivity is plotted for background sensitivity and corresponding automated perimetry. A solution
in two planes to the 3D distribution of axons in the ONH is proposed. Visual fields with induced damage in
the optic disc are comparable in pattern and quantity to glaucomatous records.
Results: The two-level simulation of the ONH facilitates the analysis of optic-cup/retinal defects. We can
generate the virtual optic pathways tailored to the age and morphology of the patient’s eye, and it is possible
to reproduce glaucomatous damage by “reverse engineering” engineering. The virtual cortical model renders
a quantitative relationship between visual defect and neural damage.
Conclusions: A two-level computing of the retina/optic nerve facilitates the analysis of neuroretinal
defects and can be incorporated to automatic perimeters to facilitate visual field analysis.
Optical coherence tomography (OCT) is an established medical imaging technique that uses light to capture micrometre resolution, three-dimensional images from optical scattering media (e.g, biological tissue). Optical coherence tomography is based on lowcoherence interferometry, typically employing near infrared light. The use of relatively long wavelength light allows it to penetrate into the scattering medium. At present, OCT imaging is used extensively for imaging the macula, optic nerve and RNFL, and aids in analysing the morphology and 1,2 quantifying changes in various disease states .
Prcis:
Despite successful trabeculectomy, eyes with similar levels of peripapillary and macular vessel densities but with worse preoperative visual field mean deviations, may experience functional and vascular decline after surgery.
Purpose:
To evaluate the retinal microcirculation change after trabeculectomy according to glaucoma severity using optical coherence tomography angiography (OCT-A).
Methods:
We enrolled 59 eyes of primary open-angle glaucoma (POAG) patients who underwent trabeculectomy. The eyes were categorized into three groups by preoperative visual field (VF) mean deviation (MD), group 1: MD>-12.0 dB, group 2: MD -12.0~-20.0 dB, and group 3: MD <-20.0 dB. OCT-A was performed preoperatively and 1 year after trabeculectomy. The differences in the radial peripapillary capillary vessel density (pVD) and macular VD between pre- and postoperative assessment were analysed and compared in each group. Factors associated with the VD change after trabeculecomy were determined using linear regression analysis.
Results:
Mean postoperative IOP and IOP reduction did not differ among three groups after trabeculectomy. Preoperative pVD (37.2 vs. 36.6%, P=1.00) and macular VD (39.0 vs. 38.4%, P=1.00) did not differ between groups 1 and 2. Group 1 and 3 showed no changes in VD parameters after trabeculectomy (all, P>0.05). However, group 2 showed statistically significant decreases in pVD (36.6 vs. 32.9%, P<0.001) and macular VD (38.4 vs. 36.0%, P=0.010) after trabeculectomy. The reduction of pVD was associated with a decrease of IOP (Coefficient (β); 0.14, P=0.032) and VF MD (β; 0.15, P=0.0116) in group 2, respectively.
Conclusion:
Following successful trabeculectomy surgery for uncontrolled glaucoma with similar IOP reduction, glaucoma eyes with advanced visual field loss showed reduced pVD and macular VD measured by OCTA. These findings may be relevant to disease progression.
Purpose:
To evaluate the changes in peripapillary retinal nerve fiber layer (pRNFL) thickness and macular ganglion cell-inner plexiform layer (mGC-IPL) thickness measured by swept-source optical coherence tomography (SS-OCT) following cataract surgery in patients with glaucoma.
Methods:
We included 42 glaucoma eyes and 42 case-matched normal eyes that underwent cataract surgery without complications. One matching set included one glaucoma eye and one case matched normal eye. The age, gender, and cataract subtype scores were similar for each group. Before and within 3 months of surgery, we measured the pRNFL thickness and mGC-IPL thickness by SS-OCT.
Results:
Following cataract surgery, the image quality (IQ) of SS-OCT improved in both groups. The thickness of the pRNFL and mGC-IPL increased in the mean values and all areas, except for pRNFL from 1 o'clock to 4 o'clock in the glaucoma group and at 1 o'clock in the normal group. Posterior subcapsular cataract was related to the change in IQ following surgery. The glaucoma and normal group showed greater pRNFL thickness change due to lesser pre-operative pRNFL thickness. Furthermore, the mGC-IPL thickness change was greater in the glaucoma group because of lesser preoperative mGC-IPL thickness. By contrast, the normal group demonstrated greater mGC-IPL thickness change due to higher cortical cataract scores.
Conclusion:
Cataracts caused the deterioration of the IQ in SS-OCT, thereby resulting in an under-measurement of the pRNFL and mGC-IPL thickness. Preoperative pRNFL and mGC-IPL were negatively associated with postoperative pRNFL and mGC-IPL thickness change in the glaucoma and normal groups. Therefore, ophthalmologists should particularly consider the effect of cataract while diagnosing glaucoma using SS-OCT.
Primary open-angle glaucoma (POAG) is a multi-factorial progressive optic neuropathy
characterized by retinal ganglion cell degeneration and progressive visual field loss which, if le untreated, may lead to blindness. Increased intraocular pressure (IOP) is considered to be the main risk factor for developing POAG, and its reduction has been
shown to correlate with a decrease in glaucoma incidence and progression. Considering
that fewer than 10% of the subjects with ocular hypertension (OHT) will develop morphological and/or functional glaucomatous damage within 5 years if not treated,
glaucoma causes and molecular changes leading to ocular tissue damage in glaucoma
are still largely unknown. The contemporary treatment of POAG is mainly oriented towards reducing IOP; the importance of the IOP reduction in other types of glaucoma,
such as the “normal pressure glaucoma”, is still discussed. The IOP value is maintained
by balancing the amount of fluid contained within the anterior and posterior chambers of
the eye; our comprehension of the mechanisms underlying the secretion and active and
passive outflow of the aqueous humor is extremely important for improving the
treatment of glaucoma. Innovative pharmacological approaches, and laser and surgical
procedures aiming to reduce IOP, have been developed in recent years.
This book provides a compendium of topics regarding IOP, aqueous humor dynamics, tonometry, and medical and surgical techniques developed to reduce the IOP in subjects with ocular hypertension or glaucoma. This is a reprint of articles from the Special Issue published online in Journal of Clinical Medicine (ISSN 2077-0383) (available at: www.mdpi.com/journal/jcm/specialissues/Ocular Hypertension).
Prcis:
Short-term use of the Balance Goggles System (BGS) in glaucoma patients was not associated with the observable changes in conventional ocular coherence tomography (OCT) imaging, but metabolic imaging using peripapillary flavoprotein fluorescence (FPF) may represent a useful adjuctive investigation.
Objective:
To determine whether the intraocular pressure (IOP)-lowering effects of the BGS are accompanied by changes in retinal thickness measured by OCT, retinal vascular density measured by ocular coherence tomography-angiography (OCTA), or novel peripapillary metabolic profiling using FPF measured by a fundus camera.
Design:
Prospective comparative case-series.
Subjects:
Eight eyes from 8 patients with open angle glaucoma ranging from mild to severe.
Methods:
In this prospective, single-center, open-label, nonrandomized, and single-arm study patients received a baseline evaluation including retinal imaging, then 1 hour of negative pressure application through the BGS, followed by repeat retinal imaging. Participants then used the BGS at home for 1 month and underwent a repeat evaluation at the conclusion of the trial.
Main outcome measures:
Changes in nerve fiber layer thickness, OCTA vascular parameters, and FPF scores.
Results:
Mean baseline IOP was 18.0±3.1 mmHg and there was no significant change in IOP at follow-up. At 1 month compared with baseline, there was a statistically significant improvement in FPF optic nerve head rim scores (12.7±11.6 to 10.5±7.5; P =0.04). In addition, there was a trend toward an increase in retinal nerve fiber layer thickness after 1 month (69.5±14.2 to 72.0±13.7; P =0.1), but there were no statistically significant differences observable with any of the OCTA vascular parameters either at 1 hour or after 1 month.
Conclusions:
There were no significant changes observable using conventional OCT imaging after short-term use of the BGS, although metabolic imaging using FPF may be a useful potential biomarker to complement existing investigations. Additional studies are warranted to further investigate these changes.
Purpose: To investigate the changes of peripapillary vessel density after Ahmed valve implantation.Methods: This is a retrospective review of 42 glaucomatous eyes that Ahmed valve implantation. Preoperative and postoperative intraocular pressure (IOP), peripapillary retinal nerve fiber layer (RNFL) thickness, peripapillary vessel density were analyzed.Results: The mean IOP was 37.49 ± 12.85 mmHg preoperatively, 13.72 ± 4.39 mmHg at 1 month postoperatively, and 12.48 ± 3.54 mmHg at postoperative 6 months which were significantly decreased after surgery (p < 0.001). Peripapillary RNFL thickness and peripapillary vessel density increased significantly at 6 months postoperatively (p = 0.013, p = 0.002, respectively). The improvement in peripapillary vessel density was associated with a greater reduction in the IOP (p < 0.001), and the lower preoperative peripapillary vessel density value (p = 0.001).Conclusions: The improvement in peripapillary vessel density was associated with a greater reduction in the IOP after Ahmed valve implantation. Measurement of peripapillary vessel density may be useful to monitor the progression of glaucoma after Ahmed valve implantation.
Significance:
Optical coherence tomography (OCT) summary measures have been suggested as a way to detect progression in eyes with advanced glaucoma. Here, we show that these measures have serious flaws largely due to segmentation errors. However, inspection of the images and thickness maps can be clinically useful.
Purpose:
This study aimed to test the hypothesis that recently suggested global OCT measures for detecting progression in eyes with advanced progression are seriously affected by segmentation mistakes and other errors that limit their clinical utility.
Methods:
Forty-five eyes of 38 patients with a 24-2 mean deviation worse than -12 dB had at least two spectral domain OCT sessions (0.8 to 4.4 years apart) with 3.5-mm circle scans of the disc and cube scans centered on the fovea. Average (global) circumpapillary retinal nerve fiber layer thickness, GcRNFL, and ganglion cell plus inner plexiform layer thickness, GGCLP, were obtained from the circle and cube scan, respectively. To evaluate progression, ΔGcRNFL was calculated for each eye as the GcRNFL value at time 2 minus the value at time 1, and ΔGGCLP was calculated in a similar manner. The b-scans of the six eyes with the highest and lowest ΔGcRNFL and ΔGGCLP values were examined for progression as well as segmentation, alignment, and centering errors.
Results:
Progression was a major factor in only 7 of the 12 eyes with the most negative values of either ΔGcRNFL or ΔGGCLP, whereas segmentation played a role in 8 eyes and was the major factor in all 12 eyes with the largest positive values. In addition, alignment (one eye) and other (three eyes) errors played a secondary role in four of the six eyes with the most negative ΔGcRNFL values.
Conclusions:
For detecting the progression of advanced glaucoma, common summary metrics have serious flaws largely due to segmentation errors, which limit their utility in clinical and research settings.
Purpose: To evaluate peripapillary and macular vessel density changes in glaucoma patients after lowering intraocular pressure (IOP) by trabeculectomy, using optical coherence tomography (OCT) angiography. Methods: A retrospective study was conducted on 20 glaucomatous eyes that underwent trabeculectomy. Preoperative and postoperative IOP, peripapillary retinal nerve fiber layer (RNFL) thickness, macular ganglion cell-inner plexiform layer thickness, peripapillary and macular vessel density measured by OCT, and OCT angiography were analyzed by the Wilcoxon signed-rank test. A regression analysis was performed to identify the factors influencing the change in vessel density. Results: The mean IOP was 31.0 ± 11.80 mmHg prior to surgery, 11.47 ± 4.52 mmHg at 1 month (p < 0.001), and 11.52 ± 3.34 mmHg at 6 months (p < 0.001). Peripapillary RNFL thickness (p = 0.002) increased significantly 6 months postoperatively. Peripapillary vessel density increased significantly 6 months after surgery (p = 0.007) and the magnitude of the reversal of peripapillary vessel density was significantly associated with a greater reduction in IOP (p < 0.001), and the lower preoperative peripapillary vessel density value (p = 0.003) and change in peripapillary vessel density increased significantly. The improvement in peripapillary RNFL thickness was associated with a greater reduction in the IOP (p = 0.011). Conclusions: Measuring peripapillary vessel density using OCT angiography was useful to identify the reversible changes in optic nerve damage caused by reducing IOP after trabeculectomy.
Glaucoma is characterized by retinal ganglion cell loss that can lead to permanent visual loss. Current clinical management practice assumes that glaucomatous visual loss is irreversible; however, there is increasing evidence that permanent vision loss and cell death is preceded by reversible functional and structural changes. We propose that these changes should be considered by glaucoma specialists when treating their patients. We discuss the neurobiological basis of this phenomenon and provide clinical evidence of reversibility in both structure and function. Specifically, we review the findings of visual field testing, contrast sensitivity, electroretinography, and imaging of the optic nerve, and their correlation with functional changes. We then discuss the clinical value of these observations in helping guide approaches towards the diagnosis and treatment of patients with glaucoma.
Purpose:
To assess the effects of local defects, segmentation errors, and improper image alignment on the performance of the commonly used optical coherence tomography (OCT) measure of progression, that is the change in global (average) circumpapillary retinal nerve fiber layer (cpRNFL) thickness (ΔG).
Methods:
One hundred fifty eyes suspected of, or with, early glaucoma had OCT circle and cube scans obtained using eye tracking on two occasions at least 1 year apart. Statistical progression was defined by fixed values of ΔG (3-8 um) and quantile regression. For a reference standard, four authors identified 30 eyes as "likely progressed," and 61 eyes that "likely had not progressed" based on OCT reports from both baseline and follow-up tests.
Results:
A ΔG criterion of 4 um had the best accuracy: 77%, with 5 false positive (8.2%) and 16 false negative (53%). A post hoc analysis of circular b-scans and OCT probability maps of these eyes indicated that segmentation errors and local progression accounted for most of these mistakes. Segmentation errors, although less common, were also present in true positives and true negatives.
Conclusions:
Local defects and segmentation errors are the primary reasons for the poor performance of cpRNFL thickness G metric. Because these problems are difficult, if not impossible, to eliminate, the G metric should not be relied on in isolation for detecting glaucomatous progression.
Translational relevance:
Local defects and segmentation errors are easily identified by viewing OCT circumpapillary images, which should be part of the standard protocol for detecting glaucomatous progression.
The aim of present study was to analyze early postoperative changes in the macular area using optical coherence tomography (OCT) after uncomplicated glaucoma filtration surgery. This prospective study included 32 patients (34 eyes) with open-angle glaucoma, which underwent trabeculectomy with or without use of mitomycin C. Exclusion criteria were macular edema, uveitis, age-related macular degeneration, blurred optical media, secondary glaucoma and angle-closure glaucoma. All standard clinical examinations were made before surgery, at the 2nd day, 1 week and 1 month after surgery. Tomography of the macula was performed during every examination using Cirrus HD OCT for the analysis of central subfield thickness. Results show that thickening of the macula was slightly higher 1 week and 1 month after operation in comparison with baseline end 2nd day postoperativelly. There was no significant difference in the change of macular thickness in patients who have used topical prostaglandins compared with those who have used other topical medications. Also, there was no difference in macular changes between patients treated with or without mitomycin C. In conclusion, we found a slight subclinical increase in macular thickness after uncomplicated trabeculectomy, for which we considered that was the result in reduction of intraocular pressure after glaucoma surgery. Macular thickening after glaucoma filtering surgery could be a physiological reaction to the stress of the retina caused by a sudden reduction of intraocular pressure and it is the consequence of altered relationship between capillary pressure and interstitial fluid pressure.
The number of patients suffering from the glaucoma disease will increase in the future. A further automation of parts of the diagnostic routine is inevitable to use limited examination times more efficiently. Optical coherence tomography (OCT) technology has become a widespread tool for glaucoma diagnosis, and data collections in the clinics have been built up in recent years that now allow for data mining and pattern recognition approaches to be applied to the diagnostic challenge. A complete pattern recognition pipeline to automatically discriminate glaucomatous from normal eyes with OCT data is proposed, implemented and evaluated. A data collection of 1024 Spectralis HRA+OCT circular scans around the optic nerve head from 565 subjects build the basis for this work. The data collection is labeled with 4 diagnoses: 453 healthy (H), 179 ocular hypertension (OHT), 168 preperimetric glaucoma (PPG), and 224 perimetric glaucoma (PG) eyes. In a first step, 6 retinal layer boundaries are automatically segmented by edge detection and the minimization of a custom energy functional, which was established in preceeding work by the author. The segmentation algorithm is evaluated on a subset consisting of 120 scans. The automatically segmented layer boundaries are compared to a gold standard (GS) created from manual corrections to the automated results by 5 observers. The mean absolute difference of the automated segmentation to the GS for the outer nerve fiber layer boundary is 2.84mum. The other layers have less or almost no segmentation error. No significant correlation between the segmentation error and scans of bad quality or glaucomatous eyes could be found for any layer boundary. The difference of the automated segmentation to the GS is not much worse than the single observer’s manual correction difference to the GS. In a second step, the thickness profiles generated by the segmentation are used in a classification system: In total, 762 features are generated, including novel ratio and principal component analysis features. “Forward selection and backward elimination” selects the best performing features with respect to the classwise averaged classification rate (CR) on the training data. The segmentations of the complete dataset were manually corrected so that the classification experiments could either be run on manually corrected or purely automated segmentations. Three classifiers were compared. The support vector machine classifier (SVM) performed best in a 10-fold cross-validation and differentiated non-glaucomatous (H and OHT) from glaucomatous (PPG and PG) eyes with a CR of 0.859 on manually corrected data. The classification system adapts to the less reliable purely automated segmentations by choosing features of a more global scale. Training with manually corrected and testing with purely automated data and vice versa shows that it is of advance to use manually corrected data for training, no matter what the type of test data is. The distance of the feature vectors to the SVM decision boundary is used as a basis for a novel glaucoma probability score based on OCT data, the OCT-GPS.
A technique called optical coherence tomography (OCT) has been developed
for noninvasive cross-sectional imaging in biological systems. OCT uses
low-coherence interferometry to produce a two-dimensional image of
optical scattering from internal tissue microstructures in a way that is
analogous to ultrasonic pulse-echo imaging. OCT has longitudinal and
lateral spatial resolutions of a few micrometers and can detect
reflected signals as small as ~10-10 of the incident optical
power. Tomographic imaging is demonstrated in vitro in the peripapillary
area of the retina and in the coronary artery, two clinically relevant
examples that are representative of transparent and turbid media,
respectively.
To demonstrate a new diagnostic technique, optical coherence tomography, for high-resolution cross-sectional imaging of structures in the anterior segment of the human eye in vivo. Optical coherence tomography is a new, noninvasive, noncontact optical imaging modality that has spatial resolution superior to that of conventional clinical ultrasonography (< 20 microns) and high sensitivity (dynamic range, > 90 dB).
Survey of intraocular structure and dimension measurements.
Laboratory.
Convenience sample.
Correlation with range of accepted normal intraocular structure profiles and dimensions.
Direct in vivo measurements with micrometer-scale resolution were performed of corneal thickness and surface profile (including visualization of the corneal epithelium), anterior chamber depth and angle, and iris thickness and surface profile. Dense nuclear cataracts were successfully imaged through their full thickness in a cold cataract model in calf eyes in vitro.
Optical coherence tomography has potential as a diagnostic tool for applications in noncontact biometry, anterior chamber angle assessment, identification and monitoring of intraocular masses and tumors, and elucidation of abnormalities of the cornea, iris, and crystalline lens.
To determine whether there were any changes in the optic disc at 2 years after trabeculectomy. To determine the factors that most influenced change and whether change was localised to any region of the optic disc.
95 patients undergoing routine trabeculectomy as part of the ongoing Moorfields/MRC 5-fluorouracil trial were recruited into the study. Eyes were imaged preoperatively (4 (SD 3) weeks) with the Heidelberg retina tomograph (HRT, Heidelberg Engineering), and at 3 months (SD 2 weeks), 1 year (SD 1 month), and 2 years (SD 1 month) after surgery. Parameters investigated for change were rim area, rim volume, and maximum cup depth. The predefined segment analysis available on the HRT analysis software was used to determine segmental change.
The images of 70 patients were analysed. Intraocular pressure reduced from 22.25 (SD 3.76) mm Hg, at the time of preoperative imaging to 15.27 (SD 4.96) mm Hg at 3 months, 14.38 (SD 3.89) mm Hg at 1 year, and 13.80 (SD 3.54) mm Hg at 2 years after trabeculectomy. An increase in rim area and rim volume was present at all time points after surgery, but was only found to be statistically significant at 2 years after surgery. Maximum depth of cup reduced by month 3 and month 12, but showed a slight increase at 2 years after surgery, although this was still lower than the preoperative measure. Segmental analysis found a significant change in rim volume in the nasal, inferonasal, superonasal, and superotemporal regions at 2 years after surgery. No significant regional localisation for change was found at any other time point or in any other parameter investigated.
Reversal of disc cupping is present at 2 years after trabeculectomy. The factor most influencing change is reduction of intraocular pressure. Segmental analysis showed that change in rim volume was greatest in the nasal, inferonasal, superonasal and superotemporal regions at 2 years.
AIMS
To investigate changes in the mechanical compliance of ex vivo human lamina cribrosa with age.
METHODS
A laser scanning confocal microscope was used to image the surface of the fluorescently labelled lamina cribrosa in cadaver eyes. A method was developed to determine changes in the volume and strain of the lamina cribrosa created by increases in pressure. The ability of the lamina cribrosa to reverse its deformation on removal of pressure was also measured.
RESULTS
Volume and strain measurements both demonstrated that the lamina cribrosa increased in stiffness with age and the level of pressure applied. The ability of the lamina cribrosa to regain its original shape and size on removal of pressure appeared to decrease with age, demonstrating an age related decrease in resilience of the lamina cribrosa.
CONCLUSIONS
The mechanical compliance of the human lamina cribrosa decreased with age. Misalignment of compliant cribriform plates in a young eye may exert a lesser stress on nerve axons, than that exerted by the rigid plates of an elderly lamina cribrosa. The resilience of the lamina cribrosa also decreased with age, suggesting an increased susceptibility to plastic flow and permanent deformation. Such changes may be of importance in the explanation of age related optic neuropathy in primary open angle glaucoma.
Objective:
To demonstrate a new diagnostic technique, optical coherence tomography, for highresolution cross-sectional imaging of structures in the anterior segment of the human eye in vivo. Optical coherence tomography is a new, noninvasive, noncontact optical imaging modality that has spatial resolution superior to that of conventional clinical ultrasonography (<20 μm) and high sensitivity (dynamic range, >90 dB).
Design:
Survey of intraocular structure and dimension measurements.
Setting:
Laboratory.
Patients:
Convenience sample.
Main Outcome Measures:
Correlation with range of accepted normal intraocular structure profiles and dimensions.
Results:
Direct in vivo measurements with micrometer-scale resolution were performed of corneal thickness and surface profile (including visualization of the corneal epithelium), anterior chamber depth and angle, and iris thickness and surface profile. Dense nuclear cataracts were successfully imaged through their full thickness in a cold cataract model in calf eyes in vitro.
Conclusions:
Optical coherence tomography has potential as a diagnostic tool for applications in noncontact biometry, anterior chamber angle assessment, identification and monitoring of intraocular masses and tumors, and elucidation of abnormalities of the cornea, iris, and crystalline lens.
Purpose:
Quantitative assessment of nerve fiber layer (NFL) thickness in normal and glaucomatous eyes, and correlation with conventional measurements of the optic nerve structure and function.
Methods:
We studied 59 eyes of 33 subjects by conventional ophthalmologic physical examination, Humphrey 24-2 visual fields, stereoscopic optic nerve head photography, and optical coherence tomography.
Results:
Nerve fiber layer thickness as measured by optical coherence tomography demonstrated a high degree of correlation with functional status of the optic nerve, as measured by visual field examination (P=.0001). Neither cupping of the optic nerve nor neuroretinal rim area were as strongly associated with visual field loss as was NFL thickness (P=.17 and P=.21,respectively). Cupping correlated with NFL thickness only when the cup was small (cup-to-diameter ratio, 0.1 to 0.3) or large (cup-to-diameter ratio, 0.8 to 1.0) (P=.006); there was no correlation between cupping and NFL thickness otherwise. Nerve fiber layer, especially in the inferior quadrant, was significantly thinner in glaucomatous eyes than in normal eyes (P=.04). Finally, we found a decrease in NFL thickness with aging, even when controlling for factors associated with the diagnosis of glaucoma (P=.03).
Conclusions:
Nerve fiber layer thickness can be measured using optical coherence tomography. These measurements provide good structural and functional correlation with known parameters.
Observations based on 28 trabeculotomy ab externo operations in 18 children with glaucoma are presented. Controlled intraocular pressure (IOP) and stable or improved optic disc status was achieved in 80% of 22 eyes followed for one year or longer. Factors associated with a poorer result were glaucoma associated with ocular syndromes, older age at the time of surgery, and corneal diameter greater than 14 mm at diagnosis. In patients with successful IOP lowering, 40% had a documented improvement in the appearance of the optic disc cup; representing an important criterion for surgical success. Reversal of cup size enlargement was observed exclusively in the first year of life in this series. In the evaluation and follow-up of children with glaucoma, it has been found useful to utilize ketamine sedation, hand-held applanation tonomefry, and dilated; stereoscopic disc examination and photography.
ObjectiveTo study longitudinal changes in optic disc topography after trabeculectomy in adult patients.DesignProspective case series.ParticipantsTwenty-five eyes of 25 patients undergoing trabeculectomy were enrolled.InterventionImages of the optic disc were obtained preoperatively and approximately 2 weeks, 4 months, and 8 months after surgery by use of a confocal scanning laser ophthalmoscope (Heidelberg Retina Tomograph).Main outcome measuresThe topographic optic disc parameters (cup volume, cup area, rim volume, rim area, cup-disc area ratio, mean cup depth, maximum depth, cup shape, and height variation contour) were measured automatically for each image with the Heidelberg Retina Tomograph Software (version 1.11).ResultsApproximately 2 weeks after surgery, the mean preoperative intraocular pressure (IOP) of 19.3 mmHg (SD, 6.4 mmHg) decreased to 6.0 mmHg (SD, 3.6 mmHg), cup volume and mean cup depth decreased, height variation contour increased, and the cup shape parameter became more negative. Approximately 4 months after surgery, mean IOP was 9.7 mmHg (SD, 4.2 mmHg), and the only statistically significant change from preoperative values of optic disc parameters was in the cup shape measure. Approximately 8 months after surgery, there was no statistically significant change in any of the optic disc parameters compared with preoperative values, although IOP was 10.4 mmHg (SD, 5.9 mmHg).ConclusionsChanges in the optic disc that may be present 2 weeks after a trabeculectomy do not appear to persist 4 and 8 months later in eyes with advanced glaucomatous optic nerve damage, except for cup shape, which was different from preoperative values at 4 months but not at 8 months.
A 17-year-old man had marked glaucomatous cupping of his left optic nerve. Two days after trabeculectomy, the appearance of the disk changed dramatically, appearing full, rather than cupped. Over the next month, with normal intraocular pressure, the optic nerve resumed its preoperative excavated appearance.
The pathogenesis of reversible cupping of the optic disk in congenital glaucoma was examined by two approaches. Human fetal, neonatal, and adult eyes were examined by histochemistry and electron microscopy to delineate the embryologic development of the optic nerve head. While the neural, glial, and vascular elements of the nerve head attain their adult configuration by midgestation, the connective tissues of the lamina cribrosa are incompletely developed at birth. The response of the optic disk cup to elevated intraocular pressure (IOP) was observed in enucleated infant and adult eyes. While no disk changes were seen in adult eyes subjected to an IOP up to 90 mm Hg for 24 hours, enlargement of the disk cup in infant eyes was documented photographically and histologically after eight to 24 hours of IOP elevations to 50 mg Hg. Reversible cupping in congenital glaucoma can be best explained by compression or posterior movement of optic disk tissues--a result of the incomplete collagenous structural framework of the lamina cribrosa during late gestation and early neonatal life.
The authors prospectively and longitudinally studied changes in optic disc topography during spontaneous reduction of intraocular pressure (IOP) in five monkeys with experimental glaucoma, using a computerized image analyzing system (Topcon IMAGEnet).
Glaucomatous optic neuropathy was produced in one eye of each animal by repeated argon laser photocoagulation of the trabecular meshwork. The duration of follow-up was 12 months. After laser treatment, IOP fluctuated and tended to increase. Spontaneous reduction in IOP was frequently observed during follow-up. Changes in optic disc parameters (vertical and horizontal cup-to-disc ratios, rim area/disc area, cup volume/disc area) that accompanied a given magnitude of spontaneous reduction in IOP at the early stage of glaucoma (first 4 months of follow-up) were compared with those at the later stage of glaucoma (last 4 months of follow-up).
All optic disc parameters improved significantly during IOP reduction at each stage of glaucoma. Although there was no significant difference between the two stages in the magnitude of IOP reduction, the extent of improvement in each disc parameter was significantly less in the later stage than in the early stage. In both stages, reversal of cupping occurred symmetrically in the vertical and horizontal dimensions. Expansion of the cup occurred symmetrically in the early stage, but this was predominantly vertical in the later stage.
These results suggest that the extent of cupping reversal after IOP reduction may decrease with progressive glaucomatous damage in primate glaucoma.
The authors investigated visual field changes in 28 eyes of 28 adult patients with early-to-moderate chronic open-angle glaucoma (COAG) in whom reversal of glaucomatous disc cupping was documented by computerized image analysis (Rodenstock Optic Nerve Head Analyzer) after intraocular pressure (IOP) reduction from 29.3 (+/- 5.9) to 19.4 (+/- 4.3) mmHg over 34.8 (+/- 24.8) weeks. Humphrey Statpac global indices (mean deviation and pattern standard deviation) improved in direct proportion to the magnitude of IOP reduction even after controlling for the possible influences of learning effect, short-term fluctuation, reliability, duration of IOP reduction, age, and pupil size. The mean visual field global indices (mean deviation and pattern standard deviation) improved in patients with IOP reduction of 40% or greater, in statistically significant contrast to no improvement of mean global indices with IOP reduction less than 35%. The beneficial effect of IOP reduction is apparent in COAG patients with topographical evidence of reversal of cupping.
We studied the change in the optic disk topography during spontaneous pressure reduction in laser-induced primate glaucoma (7 eyes, follow-up of 20 weeks) using computerized image analysis (vertical and horizontal cup-to-disk ratios CDR(V), CDR(H); neuroretinal rim area/disk area; cup volume/disk area). A significant correlation was found between the percent pressure reduction and the percent reversal in each disk parameter. There was no significant difference in the percent reversal between CDR(V) and CDR(H). These results suggest that reversal of cupping may depend on the percent pressure reduction, and may occur symmetrically in primate glaucoma.
The authors used the Humphrey Retinal Analyzer to study the effect of acute changes in intraocular pressure (IOP) on the topography of the optic nerve head in normotensive and hypertensive eyes of cynomolgus monkeys. Chronically elevated IOP was produced monocularly in monkeys by argon laser angle treatment. In 8 hypertensive eyes, the mean IOP of 51 mmHg was lowered acutely to 15 mmHg with a needle placed in the anterior chamber. In 12 normotensive eyes, the mean IOP of 16 mmHg was similarly increased to 45 mmHg. Simultaneous stereophotographs were taken both before and within 15 minutes after the IOP change. The surface of normotensive optic nerve heads moved posteriorly a mean of 17.8 microns after IOP elevation (P less than 0.02). The surface of hypertensive optic nerve heads moved anteriorly 47.4 microns after IOP lowering (P = 0.1); this change was significantly less in nerve heads with larger and deeper cups (P less than 0.02). Significant changes were not detected in disc diameter or vein diameter with acute changes in IOP. Measurable shifts in the position of the optic nerve head surface when IOP is altered may provide a future prognostic test for glaucomatous optic neuropathy.
Trabeculectomy was performed in 24 eyes affected by primary open angle glaucoma. Visual fields were measured using automated perimetry preoperatively and in the first, third, sixth and twelfth months after surgery. Significant improvement in visual field occurred in 96% of cases.
To assess change over time in the optic disk and the associated change in visual field, we retrospectively reviewed perimetry results and optic disk photographs of adult patients treated for glaucoma. Three glaucoma specialists masked to the clinical course independently reviewed optic disk stereophotographs and visual fields taken before and after treatment. Each member of each pair of stereophotographs or perimetry results, which were presented in a random sequence, were graded as better, worse, or unchanged. Of the 75 eyes, 16 (21%) showed a reversal of optic disk cupping; 20 of the 63 visual fields (31%) were classified as improved. In six of 17 eyes (35%) with a change in the disk (better or worse), a corresponding change was also noted in the visual field. The frequency of improvement in optic disk and visual field appearance was significantly (P less than .05) associated with the degree of intraocular pressure reduction.
This paper reports a direct relationship between change in the level of intraocular pressure and the visual field of patients with glaucoma: improvement in the visual field with improvement of intraocular pressure and deterioration of visual field with deterioration of intraocular pressure. The documentation of change in visual field or optic disc (worse or better) is the most certain criterion of control. Unless improvement is noted to accompany lowering of intraocular pressure, adequacy of control cannot, with certainty, be assured. This concept is based on an analysis of 77 patients having trabeculectomy and 195 patients having argon laser trabeculoplasty without alteration of the optical system of the eye, in whom the visual field was determined with Octopus computerised perimetry before and after the pressure altering event.
This report provides additional documentation that the appearance of the optic disc may improve after intraocular pressure is lowered in patients with glaucoma. Photographic records of one of the authors (GLS) were reviewed retrospectively. Seven previously unreported cases showing apparent improvement of the optic disc were found, and the patients' charts were reviewed. In two cases the improvement was transient, and in five it was lasting. Patients with evidence of disc improvement had an age range of 5 to 55 years. In one case, the scleral ring decreased in size following the lowering of intraocular pressure. In the other cases, the disc appeared to "fill in" without change in the size of the scleral ring. When improvement is short-lived, it presumably represents edema. When of longer duration, it may be a response to anterior repositioning of a posteriorly displaced lamina cribrosa, a decrease in diameter of the scleral ring, hypertrophy and/or proliferation of glial cells, or return towards normal of axonal metabolism. Because apparent improvement in the appearance of the optic disc can be subtle, it is usually not sought and is probably often unrecognized. Its true incidence is still unknown but appears to be underestimated.
Observations based on 28 trabeculotomy ab externo operations in 18 children with glaucoma are presented. Controlled intraocular pressure (IOP) and stable or improved optic disc status was achieved in 80% of 22 eyes followed for one year or longer. Factors associated with a poorer result were glaucoma associated with ocular syndromes, older age at the time of surgery, and corneal diameter greater than 14 mm at diagnosis. In patients with successful IOP lowering, 40% had a documented improvement in the appearance of the optic disc cup, representing an important criterion for surgical success. Reversal of cup size enlargement was observed exclusively in the first year of life in this series. In the evaluation and follow-up of children with glaucoma, it has been found useful to utilize ketamine sedation, hand-held applanation tonometry, and dilated, stereoscopic disc examination and photography.
Quantitative assessment of nerve fiber layer (NFL) thickness in normal and glaucomatous eyes, and correlation with conventional measurements of the optic nerve structure and function.
We studied 59 eyes of 33 subjects by conventional ophthalmologic physical examination, Humphrey 24-2 visual fields, stereoscopic optic nerve head photography, and optical coherence tomography.
Nerve fiber layer thickness as measured by optical coherence tomography demonstrated a high degree of correlation with functional status of the optic nerve, as measured by visual field examination (P = .0001). Neither cupping of the optic nerve nor neuroretinal rim area were as strongly associated with visual field loss as was NFL thickness (P = .17 and P = .21, respectively). Cupping correlated with NFL thickness only when the cup was small (cup-to-diameter ratio, 0.1 to 0.3) or large (cup-to-diameter ratio, 0.8 to 1.0) (P = .006); there was no correlation between cupping and NFL thickness otherwise. Nerve fiber layer, especially in the inferior quadrant, was significantly thinner in glaucomatous eyes than in normal eyes (P = .04). Finally, we found a decrease in NFL thickness with aging, even when controlling for factors associated with the diagnosis of glaucoma (P = .03).
Nerve fiber layer thickness can be measured using optical coherence tomography. These measurements provide good structural and functional correlation with known parameters.
The authors evaluated the relative nerve fiber layer height changes in glaucomatous eyes after reduction of intraocular pressure (IOP) after trabeculectomy using image analysis techniques.
Optic disc topography and relative nerve fiber layer height of 12 eyes of 12 patients with chronic open-angle glaucoma were measured using a Rodenstock optic nerve head analyzer and Caprioli's program for nerve fiber layer height determination before trabeculectomy and at 2 or more months after surgery.
Changes in relative nerve fiber layer height after surgery, as well as those in cup volume and rim area, showed statistically significant correlation with the degree of reduction of IOP (Spearman's correlation coefficient = 0.66; P < 0.05). Changes in the mean deviation of Humphrey visual field showed a slight correlation with IOP reduction (Spearman's correlation coefficient = 0.55; P < 0.1).
Nerve fiber layer height changes that may occur after trabeculectomy are pressure-dependent.
To analyze changes in the optic disc topography after filtration surgery.
Laser scanning tomography was performed in 10 eyes of 9 patients (mean age 65.6 +/- 8.1 years; age range 55 to 75 years) after a mean follow-up of 3.7 months, and in 8 eyes of 7 patients (mean age 63.1 +/- 7.6 years; age range 55 to 75 years) after a mean follow-up of 13.1 months.
Preoperatively, the mean intraocular pressure (IOP) was 24.4 +/- 6.9 mm Hg with maximal medication. Postoperatively at 3.7 months it was 11.0 +/- 2.2 mm Hg, and at l2.1 months it was l3.6 +/- 2.8 mm Hg. An initial reduction in IOP of more than 30 percent at 3.7 months was achieved without medication in all but 1 eye. After 12.1 months, an IOP reduction of more than 30 percent was achieved in 6 of 8 eyes (1 with medication), while 2 eyes had IOP reductions of less than 15 percent (< or = 3 mm Hg) despite medication. In the 6 eyes, the optic disc cup volume showed a decrease of more than 30 percent, while the 2 eyes without marked IOP reductions had slight increases in cup volume. Of the 2 eyes without marked decreases in cup size, 1 had normal-tension glaucoma and 1 experienced an increase in IOP of more than 25 mm Hg during the first postoperative week.
The postoperative IOP should be kept low enough to permit reversal of optic disc changes.
To investigate the relationship between optic disk topography and intraocular pressure before and after trabeculectomy with confocal scanning laser ophthalmoscopy.
The eyes of 49 consecutive patients undergoing trabeculectomy at a university-based glaucoma practice underwent preoperative and postoperative imaging using a confocal scanning laser ophthalmoscope (Heidelberg Retina Tomograph). Three images of one eye of each patient were obtained with a 15-degree field of view. Preoperative images were obtained approximately 2 months before surgery (mean +/- SD, 2.4 +/- 1.6 months). Postoperative images were obtained at least 3 months after surgery (mean, 4.5 +/- 2.6 months).
Mean preoperative intraocular pressure, postoperative intraocular pressure, and percent change in intraocular pressure respectively were 23.1 +/- 6.8 mm Hg, 12.7 +/- 7.1 mm Hg, and 43.8% +/- 29.9%. A significant association (P < .01) was found between percent decrease in intraocular pressure and decreases in cup area, cup volume, and cup/disk area ratio as well as between percent decrease in intraocular pressure and increases in rim area, rim volume, mean height contour, retinal cross-section area, and height in contour. Between 11.7% and 31.2% of the variability (R2) in these parameters was explained by the percent change in intraocular pressure. Topography changes were more strongly associated with percent change than with mean change in intraocular pressure. We found no association between percent decrease in intraocular pressure and reference plane height or maximum cup depth.
Changes in optic nerve topography were associated with reduction in intraocular pressure after trabeculectomy.
Optical coherence tomography (OCT) is a new technology that uses near-infrared light in an interferometer to produce approximately 10-microns resolution cross-sectional images of the tissue of interest. The authors performed repeated quantitative assessment of nerve fiber layer thickness in individuals with normal and glaucomatous eyes, and they evaluated the reproducibility of these measurements.
The authors studied 21 eyes of 21 subjects by OCT. Each subject underwent five repetitions of a series of scans on five separate occasions within a 1-month period. Each series consisted of three circular scans around the optic nerve head (diameters, 2.9, 3.4, and 4.5 mm). Each series was performed separately using internal (fixation with same eye being studied) and external (fixation with contralateral eye) fixation techniques. The eye studied and the sequence of testing were assigned randomly.
Internal fixation (IF), in general, provides a slightly higher degree of reproducibility than external fixation (EF). Reproducibility was better in a given eye on a given visit than from visit to visit. Reproducibility as measured by intraclass correlation coefficients were as follows: circle diameter (CD), 2.9 mm, 0.51/0.57 (normal/glaucoma) (IF), 0.43/0.54 (EF); CD, 3.4 mm, 0.56/0.52 (IF), 0.43/0.61 (EF); CD, 4.5 mm, 0.53/0.43 (IF), 0.42/0.49 (EF).
Nerve fiber layer thickness can be reproducibly measured using OCT. Internal is superior to external fixation; each circle diameter tested provides adequate reproducibility.
To evaluate macular thickness changes after uneventful cataract surgery using optical coherence tomography (OCT) and compare the findings with those of flare and cell measurements of the anterior chamber.
Clinique Sourdille, Nantes, France.
In this retrospective study, 41 eyes having uneventful cataract surgery with a clear corneal small incision and intracapsular fixation of a foldable intraocular lens were evaluated by OCT and laser flare and cell measurements preoperatively and 1, 8 to 12, and 30 to 60 days postoperatively.
Some postoperative increase in macular thickness was noted in 11 eyes. This was not related to a higher postoperative flare. Visual consequences were proportional to the macular elevation.
Clinical and subclinical thickness changes, without breakdown of the blood-aqueous barrier, can be detected after cataract surgery. Most of these changes resolve spontaneously, but their mid- and long-term significance is unknown.
Optical coherence tomography (OCT) is a novel technique that allows cross-sectional imaging of the anterior and posterior eye. OCT has a resolution of approximately 10 microns, with extremely high sensitivity (approximately 10(-10) of incident light). OCT is analogous to computed tomography, which uses x-rays, magnetic resonance imaging, which uses spin resonance, or B-scan ultrasound, which uses sound waves, but OCT uses only light to derive its image. OCT is a noncontact, noninvasive system by which retinal substructure may be analyzed in vivo. OCT is useful in the evaluation of retinal pathologies and glaucoma. In retinal disease, entities such as macular holes, macular edema, central serous chorioretinopathy, retinal vascular occlusion and other factors have been examined. Separation between the posterior vitreous and retina, or lack thereof, are seen and quantitated. In glaucoma, retinal nerve fiber layer (NFL) thickness is measured at standardized locations around the optic nerve head. A circular scan produces a cylindrical cross-section of the retina, from which the NFL can be analyzed. In addition, radial scans through the optic nerve head are used to evaluate cupping and juxtapapillary NFL thickness. OCT, a new imaging technology by which the anterior and posterior segment are seen in cross-section, may permit the early diagnosis of glaucoma, and the early detection of glaucomatous progression.
To detect and quantitate changes in optic nerve morphology after glaucoma surgery using the Heidelberg Retina Tomograph (HRT, Heidelberg Instruments, Heidelberg, Germany).
Nonconsecutive observational case series.
The authors prospectively enrolled 21 adult patients undergoing incisional glaucoma surgery for progressive glaucoma damage. Quantitative analysis of the optic nerve head by scanning laser tomography and automated perimetry were performed before and after glaucoma surgery.
Changes in optic nerve parameters were subjected to linear regression analysis with respect to percent of postoperative reduction of intraocular pressure (IOP), as well as with respect to age, refraction, preoperative cup:disc ratio, and change in visual field parameters.
Seventeen patients had pre- and postoperative images suitable for analysis. Mean IOP at the time of image acquisition before surgery was 30.5+/-12 mm Hg, and after surgery 11.8+/-5.2 mm Hg (mean follow-up, 26+/-7 weeks). Eleven of 13 (85%) patients having IOP reduction of greater than 40% showed improvement in optic disc parameters. All four patients with less than 25% reduction in IOP showed worsening of most parameters. Changes in optic disc parameters were highly correlated with percent IOP reduction and with age. The parameters in which change most strongly correlated with percent change of IOP were cup area, rim area, cup:disc ratio, and mean cup depth (each, P<0.005). The age of the patient correlated highly with change in maximum cup depth (P<0.005). Refraction and clinically determined cup:disc ratio correlated poorly with changes in measured optic disc parameters. Clinical improvement in visual fields was correlated with the degree of improvement of cup:disc ratio (P = 0.025).
Most patients showing a 40% lowering of IOP after glaucoma surgery show improved optic nerve morphology as measured by the HRT. The amount of improvement correlated highly with the percent reduction of IOP.
To study longitudinal changes in optic disc topography after trabeculectomy in adult patients.
Prospective case series.
Twenty-five eyes of 25 patients undergoing trabeculectomy were enrolled.
Images of the optic disc were obtained preoperatively and approximately 2 weeks, 4 months, and 8 months after surgery by use of a confocal scanning laser ophthalmoscope (Heidelberg Retina Tomograph).
The topographic optic disc parameters (cup volume, cup area, rim volume, rim area, cup-disc area ratio, mean cup depth, maximum depth, cup shape, and height variation contour) were measured automatically for each image with the Heidelberg Retina Tomograph Software (version 1.11).
Approximately 2 weeks after surgery, the mean preoperative intraocular pressure (IOP) of 19.3 mmHg (SD, 6.4 mmHg) decreased to 6.0 mmHg (SD, 3.6 mmHg), cup volume and mean cup depth decreased, height variation contour increased, and the cup shape parameter became more negative. Approximately 4 months after surgery, mean IOP was 9.7 mmHg (SD, 4.2 mmHg), and the only statistically significant change from preoperative values of optic disc parameters was in the cup shape measure. Approximately 8 months after surgery, there was no statistically significant change in any of the optic disc parameters compared with preoperative values, although IOP was 10.4 mmHg (SD, 5.9 mmHg).
Changes in the optic disc that may be present 2 weeks after a trabeculectomy do not appear to persist 4 and 8 months later in eyes with advanced glaucomatous optic nerve damage, except for cup shape, which was different from preoperative values at 4 months but not at 8 months.
To investigate changes in the mechanical compliance of ex vivo human lamina cribrosa with age.
A laser scanning confocal microscope was used to image the surface of the fluorescently labelled lamina cribrosa in cadaver eyes. A method was developed to determine changes in the volume and strain of the lamina cribrosa created by increases in pressure. The ability of the lamina cribrosa to reverse its deformation on removal of pressure was also measured.
Volume and strain measurements both demonstrated that the lamina cribrosa increased in stiffness with age and the level of pressure applied. The ability of the lamina cribrosa to regain its original shape and size on removal of pressure appeared to decrease with age, demonstrating an age related decrease in resilience of the lamina cribrosa.
The mechanical compliance of the human lamina cribrosa decreased with age. Misalignment of compliant cribriform plates in a young eye may exert a lesser stress on nerve axons, than that exerted by the rigid plates of an elderly lamina cribrosa. The resilience of the lamina cribrosa also decreased with age, suggesting an increased susceptibility to plastic flow and permanent deformation. Such changes may be of importance in the explanation of age related optic neuropathy in primary open angle glaucoma.
To evaluate changes in retinal thickness immediately after cataract surgery.
Retinal thickness before and 0.5 hours after uneventful cataract surgery was determined in 10 patients at 15 different points at the posterior pole by optical coherence tomography (OCT).
The mean retinal thickness at the posterior pole was 251 microm (+/-30 microm) before cataract surgery and 249 microm (+/-25 microm) after cataract surgery. No statistical difference between pre- and postoperatively values could be evaluated (P = 0.8).
The results indicate that uncomplicated cataract surgery does not influence retinal thickness immediately postoperatively in eyes without ocular pathologies.
Optical coherence tomography: a new tool for glaucoma diagnosis [review]
- Js Schuman
- Mr Hee
- Av Arya
Schuman JS, Hee MR, Arya AV, et al. Optical coherence tomography: a new tool for glaucoma diagnosis [review]. Curr Opin Ophthalmol 1995;6:89–95. [PubMed: 10150863]
The effect of change in intraocular pressure on the natural history of glaucoma
- Spaeth