Ability of Fourier-domain Optical Coherence Tomography to Detect Retinal Ganglion Cell Complex Atrophy in Glaucoma Patients
Department of Ophthalmology, Haydarpasa Numune Research and Education Hospital, Istanbul, Turkey.Journal of glaucoma (Impact Factor: 2.11). 03/2012; 22(7). DOI: 10.1097/IJG.0b013e31824d1f97
PURPOSE:: To evaluate the diagnostic ability of Fourier-domain optical coherence tomography (FD-OCT) measurements in both normal individuals and patients with different stages of glaucoma. PATIENTS AND METHODS:: A total of 113 patients diagnosed with glaucoma and classified into different stages of glaucoma according to Glaucoma Staging System 2 and 30 healthy individuals were included in this study. In all patients, parameters of both the retinal ganglion cell complex (GCC) and the peripapillary retinal nerve fiber layer were measured by FD-OCT (RTVue-100). Comparisons were made from measurements in patients with different stages of glaucoma. RESULTS:: Both GCC and retinal nerve fiber layer thickness values of patients with glaucoma were statistically significantly lower compared with those of healthy individuals. As the stage of glaucoma progressed, the mean GCC and retinal nerve fiber layer thickness values decreased. CONCLUSIONS:: GCC and retinal nerve fiber layer thickness measurements performed by FD-OCT showed high diagnostic ability in detecting glaucoma. Mean thickness values can be determined for each glaucoma stage.
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ABSTRACT: Purpose of review: With the rapid adoption of spectral domain optical coherence tomography (SDOCT) in clinical practice and the recent advances in software technology, there is a need for a review of the literature on glaucoma detection and progression analysis algorithms designed for the commercially available instruments. Recent findings: Peripapillary retinal nerve fiber layer (RNFL) thickness and macular thickness, including segmental macular thickness calculation algorithms, have been demonstrated to be repeatable and reproducible, and have a high degree of diagnostic sensitivity and specificity in discriminating between healthy and glaucomatous eyes across the glaucoma continuum. Newer software capabilities such as glaucoma progression detection algorithms provide an objective analysis of longitudinally obtained structural data that enhances our ability to detect glaucomatous progression. RNFL measurements obtained with SDOCT appear more sensitive than time domain OCT (TDOCT) for glaucoma progression detection; however, agreement with the assessments of visual field progression is poor. Summary: Over the last few years, several studies have been performed to assess the diagnostic performance of SDOCT structural imaging and its validity in assessing glaucoma progression. Most evidence suggests that SDOCT performs similarly to TDOCT for glaucoma diagnosis; however, SDOCT may be superior for the detection of early stage disease. With respect to progression detection, SDOCT represents an important technological advance because of its improved resolution and repeatability. Advancements in RNFL thickness quantification, segmental macular thickness calculation and progression detection algorithms, when used correctly, may help to improve our ability to diagnose and manage glaucoma.
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ABSTRACT: To investigate the relationship between scleral mechanical properties, its birefringence, and the anisotropy of birefringence alteration in respect of the direction of the strain by using PS-OCT. The scleral birefringence of thirty-nine porcine eyes was measured with a prototype PS-OCT. A rectangle strip of sclera with a width of 4 mm was dissected at the temporal region 5 mm apart from the optic nerve head. The strain and force were measured with a uniaxial tension tester as the sample was stretched with a speed of 1.8 mm/min after preconditioning. The birefringence of the sample was measured by PS-OCT at the center of the sample before applying, denoted as inherent birefringence, and after applying stretching of 6.5% strain. The birefringence alteration was obtained by these two measurements and correlations between birefringence and elastic parameters, tangent modulus, and structural stiffness were examined. Twenty and 19 porcine eyes were stretched in meridional or equatorial directions, respectively. A moderate positive correlation was found between the inherent birefringence and the structural stiffness. A moderate positive correlation was also found between the inherent birefringence and the tangent modulus. The birefringence increased by strains. Marginal significance was found in the birefringence alteration between meridional and equatorial strains, where the mean birefringence elevation by meridional strain was higher than that by equatorial strain. The birefringence was found to be altered by applying strain and also be related with inherent birefringence. This implies the birefringence of the sclera of the in vivo eye also could be affected by its mechanical property.
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ABSTRACT: Purpose: To evaluate the influence of topographic profiles (i.e., inner directional angle and angular width) of localized retinal nerve fiber layer (RNFL) defects on the diagnostic performance of macular ganglion cell-inner plexiform layer (GCIPL) thickness in discriminating preperimetric glaucoma (PPG) eyes from normal control eyes. Methods: The ganglion cell analysis algorithm in Cirrus OCT was performed to determine the macular GCIPL thickness. Areas under the receiver operating characteristic curves (AUROCs) and the sensitivities/specificities based on an internal normative database were evaluated. The effect of the inner directional angle and the angular width of localized RNFL defects on the diagnostic performance of macular GCIPL parameters were evaluated by using linear-by-linear association analysis and logistic regression analysis. Results: Ninety-two patients with PPG and 92 age-matched healthy control subjects were enrolled in this study. The AUROC of the best parameters in macular GCIPL was 0.823 (inferotemporal sector), which showed no significant difference in comparison to the best parameters of peripapillary RNFL (7 o'clock sector, 0.764) and optic nerve head (rim area, 0.767) (for all comparisons, P > 0.05). A significant linear association was observed between the inner directional angle of RNFL defects and the sensitivity of macular GCIPL parameters for detecting RNFL defects. The angular width of RNFL defects was not significantly associated with the sensitivity of macular GCIPL parameters. Conclusions: The diagnostic ability of macular GCIPL parameters was comparable to that of peripapillary RNFL and ONH parameters in PPG. The inner directional angle of RNFL defects, but not the angular width, affects the diagnostic sensitivity of macular GCIPL parameters.
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