Does the ISNT rule apply to the radial peripapillary capillary vessel density in OCT angiography?

PURPOSE

To investigate the applicability of ISNT (inferior ≥ superior ≥ nasal ≥ temporal), IST (inferior ≥ superior ≥ temporal), and T min (temporal quadrant with the minimum value) rules to the peripapillary nerve fiber layer (NFL) thickness and radial peripapillary capillary (RPC) vessel density (VD) using Optical Coherence Tomography (OCT) and OCT angiography (OCT-A).

MATERIALS AND METHODS

This cross-sectional study included 134 eyes of 74 healthy individuals. NFL thickness and RPC VD were measured in all four quadrants using OCT and OCT-A in order to determine the number of eyes that obey the ISNT, IST, and T min rules.

RESULTS

Mean age was 48.8 ± 15.5 (range 25-82) years. The ISNT rule was valid in 52 eyes (38.81%) on OCT and only 12 eyes (8.95%) on OCT-A scans. The IST rule was followed by 83 (61.94%) and 37 (27.61%) eyes on OCT and OCT-A scans respectively. The T min rule was valid in 86 eyes (64.18%) in OCT scans and in 26 eyes (19.4%) in OCT-A scans.

CONCLUSION

The topography of the RPC network does not obey the ISNT rule in healthy eyes. The ISNT rule and its variants were found to be more relevant in OCT NFL thickness measurements compared to OCT-A RPC VD measurements.

Sectorwise analysis of peripapillary vessel density and retinal nerve fiber layer thickness in exfoliation syndrome

PURPOSE

This cross-sectional study compared the peripapillary vessel density and retinal nerve fiber layer (RNFL) thickness in patients with exfoliation syndrome (XFS) and healthy controls for evaluation of the early structural and vascular alterations in XFS.

METHODS

One eye was included from 75 patients with XFS and 54 healthy controls. The patients with XFS were matched the controls for age, intraocular pressure and axial length. The vascular density of the radial peripapillary capillaries (RPCs) and the peripapillary RNFL thickness were evaluated with optical coherence tomography angiography.

RESULTS

The mean peripapillary RNFL thicknesses of the groups were similar in all sectors (p > 0.05 for all). However, eyes with XFS demonstrated lower mean peripapillary vessel densities in all areas (p < 0.05 for all) except for the nasal sector (p = 0.68) compared to the controls. The gradual age correlated decline in the peripapillary RNFL thickness and the RPC vessel density observed in the healthy eyes was absent in XFS (r = - 0.14 p = 0.65 and r = - 0.23 p = 0.05).

CONCLUSIONS

Alterations in the peripapillary vascular density despite a preserved RNFL thickness in XFS supports the hypothesis that vascular alterations may precede structural alterations and have an important role in the pathogenesis of XFS. XFS may have different effects on the microvasculature of different peripapillary areas, with the nasal sector being mostly preserved.

Microvascular and structural alterations in the optic nerve head of advanced primary open-angle glaucoma compared with atrophic non-arteritic anterior ischemic optic neuropathy

PURPOSE

This cross-sectional study compared the peripapillary vessel density (VD), peripapillary retinal nerve fiber layer (RNFL) thickness, and optic nerve head (ONH) parameters between eyes with atrophic non-arteritic anterior ischemic optic neuropathy (NAION) and eyes with advanced primary open-angle glaucoma (POAG) matched for visual field mean deviation.

METHODS

Peripapillary VDs and RNFL thicknesses in the peripapillary region, and 4 sectors (superior, inferior, nasal, and temporal), and scanning laser ophthalmoscopy parameters of the ONH were evaluated with optical coherence tomography angiography (OCTA) among 21 atrophic NAION cases, 26 advanced POAG cases, and 30 age- and sex-matched healthy controls.

RESULTS

The POAG eyes had lower peripapillary VDs in all areas compared with the NAION eyes, which was most marked in the inferior and nasal sectors (p=0.005 for both). RNFL loss was similar between the 2 groups in all areas, except for a preserved thickness in the inferior sector in NAION eyes (p=0.01). Peripapillary VD demonstrated stronger correlations with global RNFL thickness in the peripapillary region in the NAION eyes compared with that of the POAG eyes (r=0.91 p<0.00001, r=0.42 p=0.03 respectively). In multivariate analysis, the peripapillary VD correlated with age and RNFL thickness in the POAG eyes while it correlated with SSI and RNFL thickness in the NAION eyes.

CONCLUSIONS

A tendency for a lower peripapillary VD despite similar visual field mean deviation values may infer a more prominent role of the vascular regression in POAG compared with NAION.

Vascular density of optic nerve head in diabetic retinopathy using optical coherence tomography angiography

Purpose

To measure optic nerve head (ONH) blood perfusion using optical coherence tomography angiography (OCTA) at various stages of diabetic retinopathy (DR).

Methods

One hundred seventy six eyes of 94 patients included in this retrospective single-centre cross-sectional study. The subjects were studied in normal, no diabetic retinopathy (NDR), non-proliferative diabetic retinopathy (NPDR) and proliferative retinopathy (PDR) groups. The eyes were subjected to AngioDisc ONH imaging using OCTA for papillary (Disc) and peripapillary (RPC) vascular density (VD) evaluation.

Results

The mean age of the participants was 56.08 ± 8.87 years and 34 (36.2 percent) were male. With increased DR severity, a statistically significant decrease in peripapillary VD was found. The study showed that only VD of the whole RPC (W-RPC) could be a valid biomarker in the staging assessment. VD of RPC, in all subsections, was considerably different from normal cases in the PDR group. Visual acuity was correlated with whole image ONH VD. The duration of DM, FBS, hyperlipidemia and DME had no effect on the ONH perfusion.

Conclusions

The study showed that only the W-RPC VD could be a reasonable marker in the staging assessment. VDs assessed by OCTA can be useful for assessing and tracking early ONH changes in DR patients.

Effect of silicone oil on peripapillary capillary density in patients with rhegmatogenous retinal detachment

Purpose

To evaluate the effect of silicone oil (SO) on peripapillary blood flow using OCT angiography.

Methods

This prospective case series recruited patients with unilateral rhegmatogenous retinal detachment (RRD) who underwent vitrectomy and SO tamponade. Patients were examined before SO removal and at 10 days, 1 month, and 3 months after SO removal on a spectral domain OCT angiography device (RTVue XR Avanti, Optovue Inc., CA, USA) for the measurement of radial peripapillary capillaries (RPC) vessel density (VD) in global field, superior hemifield, and inferior hemifield. Changes in RPC VD following SO removal were compared between affected eyes and contralateral eyes.

Results

Twenty-two patients were analyzed. The average duration of SO tamponade was 101.3 days (range, 90 to 119 days). After SO removal, global RPC VD increased by 1.3% (95%CI, 0.3 to 2.3%), compared with a − 0.4% (95%CI, − 1.4 to 0.7%) change in contralateral eyes (P = 0.007). The increase in RPC VD after SO removal mainly occurred in the superior hemifield, which was 1.6% (95%CI, 0.6 to 2.7%). The increase in RPC VD in the inferior hemifield was 1.0% (95%CI, − 0.2 to 2.1%) after SO removal.

Conclusions

We detected a mild increase in peripapillary capillary density after SO removal, mainly in the superior hemifield. Our results suggested that SO tamponade could have negative effect on peripapillary blood flow, possibly by capillary compression.

Optical coherence tomography angiography analysis of fabry disease

PURPOSE

Fabry disease (FD) is characterized by a deficiency in α-galactosidase A activity that leads to the cumulative deposition of unmetabolized glycosphingolipids within organs, including the vascular endothelium and the eyes. The purpose of this study was to assess the effects of FD on the retinal microvasculature, foveal avascular zone (FAZ), macular thickness and retinal nerve fiber layer (RNFL) using optical coherence tomography angiography (OCT-A).

METHODS

Twenty-five patients (14 female and 11 male; mean age 33.16 ± 11.44) with genetically verified FD were compared with 37 age- and sex-matched healthy controls (mean age 32.36 ± 15.54). The vessel density (VD) values of the superficial and deep capillary plexuses (SCP and DCP), the area of the FAZ, the density of radial peripapillary capillaries (RPC), the macular thickness and the retinal nerve fiber layer thickness were measured by OCT-A examination.

RESULTS

The patients showed significantly lower VD values than controls in the foveal regions of both SCP and the DCP (21.15 ± 5.56 vs. 23.79 ± 4.64 (p = 0.048), 37.92 ± 6.78 vs. 41.11 ± 5.59 (p = 0.048), respectively). The FAZ was significantly larger in the FD group than in the control group (0.3 ± 0.1 vs. 0.24 ± 0.08 (p = 0.011)). No significant difference was identified in measurements of RPC density, peripapillary RNFL thickness or macular thickness between the two groups (p > 0.05 for all).

CONCLUSION

Decreased VD and an enlarged foveal avascular area suggest possible changes in the retinal microvasculature of patients with FD. OCT-A can serve as a useful, noninvasive, quantitative tool for diagnosing FD and monitoring its progression.

Associations between changes in radial peripapillary capillaries and occurrence of disc hemorrhage in normal-tension glaucoma

PURPOSE

In order to clarify the association between peripapillary vascular changes and disc hemorrhage (DH) occurrences over time, we analyzed the density of radial peripapillary capillary (RPC) and clinical parameters during follow-up periods in patients with normal-tension glaucoma (NTG).

METHODS

Seventy-seven eyes of 77 NTG patients were subjected to analysis. We selected patients who had an initial optical coherence tomography angiography (OCTA) scan in 2015 and who had another OCTA scan in 2018 with both OCTA scans showing good-quality images. We investigated the relationships between DH occurrence and each of the following parameters: RPC density, circumpapillary retinal nerve fiber layer (cpRNFL) thickness slope and total deviation (TD) slope.

RESULTS

In the period between the initial and final OCTA, we categorized the patients into 53 sides with DH (DH group) and 101 sides without DH (non-DH group). The ΔRPC density of sides with DH was significantly greater than that of sides without DH (DH, - 4.42 ± 6.43%; without DH, - 2.48 ± 5.29%; p = 0.0469). The cpRNFL thickness slope of sides with DH was significantly faster than that of sides without DH (DH, - 2.85 ± 3.17; without DH, - 0.74 ± 2.46 μm/y; p < 0.0001). The TD slope of sides with DH was significantly faster than that of sides without DH (DH, - 0.50 ± 0.77; without DH, - 0.22 ± 0.53 dB/y; p = 0.0163). As DH occurrence increased, the RPC density significantly decreased (r = -0.255, p = 0.0014). Stepwise multiple regression analysis to identify factors influencing RPC changes showed that frequency of DH (β = - 0.224, p = 0.008) and central corneal thickness (β = - 0.220, p = 0.009) were significantly associated with RPC changes.

CONCLUSIONS

DH occurrence may prompt the structural and vascular deterioration of NTG.

Purtscher-like retinopathy associated with cerebro- or cardiovascular surgery

Purpose

To report the findings in five patients of Purtscher-like retinopathy that developed after cerebro- or cardiovascular surgeries.

Observations

Three women and two men with a mean age of 56.6 years were studied. They had had cerebro- or cardiovascular disease that was treated by major vascular surgery. Postoperatively, all of the patients developed multiple patches of retinal whitening in the area corresponding to the radial peripapillary capillaries in the posterior pole of the eye uni- or bilaterally. In two patients, the optic nerve head was involved which affected their vision severely. Hematological examinations showed hypercoagulable state after the surgeries. The retinal pathologies abated with time.

Conclusions and importance

These results indicate that major cardio- or cerebrovascular surgeries can cause Purtscher-like retinopathy. The hypercoagulable state and specific structures of the radial peripapillary capillaries may play a role in pathogenesis of this disease.