Fig 5 - uploaded by Taku Wakabayashi
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Simulation of full-scattered-pan-retinal laser photocoagulation with different spacing and patterns. Circles of 400-lm diameter, in an equidistant or grid pattern, with 0-, 0.25-, 0.50-, 0.75-or 1.0-spot width spacing, were drawn using SolidWorks Ò . The numbers of spots and the theoretical photocoagulation indexes are shown in Table 2.
Source publication
Purpose
To evaluate the impact of spot size, spacing, pattern, duration and intensity of burns on the photocoagulation index, using a geometric simulation of pan‐retinal laser photocoagulation.
Methods
Simulations of full‐scattered pan‐retinal laser photocoagulation were performed on a retinal map, using a geometry‐based method. Simulations consis...
Contexts in source publication
Context 1
... numbers of spots in full-scattered PRP with a 400-lm diameter, in an equidistant pattern of 1.0-, 0.75-, 0.5-, 0.25-and 0-spot widths apart, were 1794, 2352, 3192, 4626 and 7218, respectively (Fig. 5). The corresponding photocoagulation indexes were 20.6%, 27.1%, 36.7%, 53.2% and 83.1%, respectively ( Table ...
Context 2
... numbers of spots in full-scattered PRP with a 400-lm diameter, in an equidistant pattern of 1.0-, 0.75-, 0.5-, 0.25-and 0-spot widths apart, were 1794, 2352, 3192, 4626 and 7218, respectively (Fig. 5). The corresponding photocoagulation indexes were 20.6%, 27.1%, 36.7%, 53.2% and 83.1%, respectively ( Table ...
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Citations
... They postulated 2 mechanisms for the increased choroidal flow. One mechnism was the redistribution of choroidal blood flow from the obliterated peripheral capillaries to the posterior pole, and the other was choroidal inflammation induced by PRP [19,20]. ...
Introduction
Diabetic retinopathy (DR) is microangiopathy causing ischemia leading to proliferative diabetic retinopathy and macular edema. Panretinal photocoagulation (PRP) reverses the ischemia leading to regression of neovessels. Most previous studies showed the large vessel effects of PRP, while optical coherence tomography angiography (OCTA) allowed noninvasive quantification of microvascular retinal changes.
Aim
To study the effect of PRP on microvascular retinal vessels in a detailed manner at different retinal and choroidal levels using OCTA.
Patients and methods
This study was a prospective interventional study. 30 eyes of 18 diabetic patients with PDR were included. All patients were evaluated clinically and with OCTA (Avanti RTVue-XR system, Optovue) to evaluate superficial and deep vessels density (VDs), choroidal flow, and FAZ area before PRP (base line) and 1 month and 6 months after PRP.
Results
PRP improved vessels density at superficial (SCP), deep (DCP), and choriocapillaris levels. Foveal vessel density at SCP and DCP were statistically significantly increased. SCP was 28.76 ± 2.56 at base line and was increased to 29.84 ± 2.47 and 30.89 ± 2.20 after 1 month and after 6 months, respectively. DCP was 34.08 ± 5.59 at base line and was increased to 34.93 ± 5.66 and 36.09 ± 5.62 after 1 month and after 6 months, respectively. Foveal choriocapillaris was statistically significantly increased from 63.04 ± 2.66 at base line to 63.48 ± 2.65 and 63.98 ± 2.78 after 1 month and 6 months, respectively. Choroidal flow was increased from 1.74 ± 0.07 at base line to 1.75 ± 0.09 at 1 month which was nonsignificant (P = 0.72), but it was significantly increased to 1.87 ± 0.27 6 months after PRP (P = 0.009). FAZ area was significantly improved after PRP. FAZ area was decreased from 0.56 ± 0.27 at base line to 0.50 ± 0.21 after 1 month and to 0.46 ± 0.21 after 6 months.
Conclusion
OCTA parameters were significantly improved by PRP in PDR patients, possibly due to redistribution of blood in occluded capillary plexuses.
Trials registry : NCT04976361.
... Panretinal laser photocoagulation (PRP) can destroy some relatively hypoxic tissues in the outer layer of the retina and fundamentally reduce the oxygen consumption of the retina, thereby improving the hypoxic condition of the inner layer of the retina. Therefore, it can effectively inhibit the release of some neovascular factors caused by hypoxia, thereby reducing the regeneration of neovascularization [22]. According to this experiment, the thickness of the macular retina decreased significantly 6 months after surgery compared with that before surgery (t = 6:93, P = 0:000 < 0:01), with statistical differences. ...
This study aimed at investigating the clinical effect of ranibizumab combined with panretinal photocoagulation in the treatment of macular edema in diabetic retinopathy (DR) patients. A parametric deformation model was constructed, and based on this, it was evaluated using optical coherence tomography (OCT) combined with fluorescein fundus angiography (FFA). 56 DR patients (80 eyes) who needed surgery were selected for OCT and FFA scanning, and 0.5 mg ranibizumab was administered intravitreal injection before surgery. It should observe the OCT and FFA image characteristics of patients. In addition, the vision correction status before the surgery, 1 month, 3 months, and 6 months after the surgery, the thickness of the macular retina, operation time, the number of intraoperative electrocoagulation, and complications of patients were recorded. It was found that 82.85% of patients had improved visual acuity after surgery. Compared with preoperative, the average logarithm of the minimum angle of resolution (logMAR) of patients at 6 months after surgery increased significantly ( P < 0.01 ). With the increase of the grade of fibrosis and the grade of hemorrhage, the logMAR visual acuity recovery at 6 months after the surgery became worse; the macular retinal thickness at 6 months after the surgery decreased significantly ( P < 0.01 ). With the increase of the grade of fibrous proliferation and the grade of bleeding, the operation time, the number of electrocoagulation, and the possibility of iatrogenic holes of patient would increase. It can be known that ranibizumab combined with panretinal photocoagulation surgery could not only reduce the macular edema but also effectively reduce the intraoperative bleeding, simplify the removal of proliferative membranes, decrease the number of electrocoagulation, and shorten the operation time, enhancing the visual function of patients.
... The protocol determines the total area of photocoagulated retinal lesions. In a previous study, we calculated this area using geometric methods and calculated the photocoagulation index [20,21], which refers to the ratio of the total retinal photocoagulated lesion area to the whole retina, for full-scatter PRP and scatter PRP. This was the first attempt to quantitatively compare full-scatter PRP with scatter PRP [20]. ...
... Simulations of scatter PRP and full scatter PRP (size 400 μm on the retina, 1 spot width apart) were performed using a geometry-based simulation as previously described [20,21]. To facilitate a better understanding of some relevant concepts, we describe important aspects of the geometry-based simulation as follows. ...
Background
During panretinal photocoagulation (PRP), the outer retina, especially the photoreceptors, are destroyed. During such procedures, the impact of the retinal photocoagulation, which is performed in the same photocoagulated area, may change if it is applied to different locations with different photoreceptor densities. Thus, we aimed to evaluate the influence of photoreceptor density on PRP.
Methods
We constructed a three-dimensional (3D) average distribution of photoreceptors with 3D computer-aided design (CAD) software using previously derived photoreceptor density data and calculated the number of photoreceptors destroyed by scatter PRP and full-scatter PRP (size 400-μm on the retina, spacing 1.0 spot) using a geometry-based simulation. To investigate the impact of photoreceptor density on PRP, we calculated the ratio of the number of photoreceptors destroyed to the total number of photoreceptors, termed the photoreceptor destruction index.
Results
In this 3D simulation, the total number of photoreceptors was 96,571,900. The total number of photoreceptors destroyed by scatter PRP and full-scatter PRP were 15,608,200 and 19,120,600, respectively, and the respective photoreceptor destruction indexes were 16.2 and 19.8%, respectively.
Conclusions
Scatter PRP is expected to have 4/5 of the number of photoreceptors destroyed by full-scatter PRP.
... As it is shown previously, the short-pulse laser delivery system results in less destructive and possibly antiischemic effects at the molecular levels. [41,42] In contrast to previously published investigation on choroidal ow following PRP by Takahashi et al. submacular choroidal owdid not change signi cantly after PRP in our study based on OCTA. They had used laser Doppler owmetry and observed a signi cant rise in subfoveal choroidal ow 1 month following PRP in the cases without clinically signi cant macular edema [43]. ...
Background: To evaluate the changes of macular vascular density in the superficial capillary (SCP) and the deep capillary plexus (DCP), Foveal avascular area (FAZ), choroidal flow, macular thickness and parapapillary flow after panretinal photocoagulation (PRP).
Method: In this prospective interventional non-comparative case series, patients with very severe nonproliferative (NPDR) and early proliferative diabetic retinopathy (PDR) and no significant macular edema who were candidates for panretinal photocoagulation underwent measurement of corrected distance visual acuity (CDVA), optical coherence tomography (OCT), Optical coherence tomography angiography (OCTA) at the baseline (1–5 days before PRP), 1, and 5 to 7 months following completion of PRP treatment.
Results: Thirty-nine eyes from 21 patients with diabetes were enrolled. foveal SCP (P > 0.1), foveal DCP (P > 0.1), parafoveal SCP (P > 0.1), and parafoveal DCP (P > 0.1) did not change 1 month and 6 months after PRP. The parafoveal inner retina thick slab density was significantly decreased at 6 months after PRP (p=0.015). Deep FAZ area constricted 6 months following PRP (P = 0.075). Based on calculated circularity index, the FAZ area became significantly more circular. (P=0.047). One month after PRP the inside disc vascular density was significantly increased from baseline (p=0.041); while, it was decreased to lower than baseline amount, 6 months after PRP .
Conclusion: Although OCTA parameters were not significantly affected by PRP at both short- (1-month) long-term (6-month) follow-up, but FAZ area may be become more circular and regular after PRP may be due to reflow of occluded capillary plexus.
Background
To evaluate the changes of macular vascular density in the superficial capillary (SCP) and the deep capillary plexus (DCP), foveal avascular area (FAZ), choroidal flow, and macular thickness after pan-retinal photocoagulation (PRP).
Methods
In this prospective interventional non-comparative case series, patients with very severe nonproliferative (NPDR) and early proliferative diabetic retinopathy (PDR) and no significant macular edema who were candidates for pan-retinal photocoagulation underwent measurement of corrected distance visual acuity (CDVA), optical coherence tomography (OCT), Optical coherence tomography angiography (OCTA) at the baseline, 1, and 6 months following completion of PRP treatment.
Results
Thirty-nine eyes from 21 patients with diabetes were enrolled. Superficial and deep capillary plexus densities in the foveal and parafoveal area didn’t change significantly 1 and 6 months post-PRP ( p > 0.1 in all of them). The FAZ area constricted 6 months following PRP ( p = 0.075). Based on the calculated circularity index, the FAZ became significantly more circular after 6 months of follow-up ( p = 0.047). Although the choroidal flow area increased after PRP this increase wasn’t statically significant neither at 1 month nor at 6 months post-PRP ( p = 0.31 and 0.23, respectively).
Conclusion
Although OCTA parameters were not significantly affected by PRP at both short-term (1 month) and long-term (6 months) follow-ups, the FAZ area became significantly circular after PRP may be due to redistribution of blood flow in hypoperfused foveal capillary plexus.
