Peripapillary Vessel Density in Glaucomatous Eyes: Comparison Between Pseudoexfoliation Glaucoma and Primary Open-angle Glaucoma

Comparison of intraocular pressure fluctuation and glaucoma progression rate between phakic and pseudophakic eyes in pseudoexfoliation glaucoma

The management of patients with concurrent pseudoexfoliation glaucoma (PXG) and cataract is challenging given its worse prognosis compared to other glaucoma types and the increased risk associated with cataract surgery. In this retrospective study, we investigated the long-term outcomes of cataract surgery in patients with PXG. We enrolled patients with PXG who had undergone cataract surgery at least 2 years previously and compared them with mean deviation (MD) matched patients with phakic eyes. The results showed that both groups experienced a decrease in MD, with the group of pseudophakic eyes exhibiting a significantly higher rate of decline (-2.15 ± 2.66 dB/year vs. -0.86 ± 0.95 dB/year; P = 0.040). Similarly, there was a trend towards more rapid thinning of the retinal nerve fiber layer in the pseudophakic group (-2.92 ± 2.34 μm/year vs. -1.79 ± 1.71 μm/year; P = 0.074). No significant differences in the intraocular pressure parameters were observed between the two groups. Multivariate analysis revealed that pseudophakic lens status was significantly associated with a faster rate of MD decline in patients with PXG (regression coefficient, -1.391; P = 0.022). These findings underscore the importance of close monitoring of patients with pseudophakic PXG to effectively manage glaucoma progression.

Diagnostic ability of vessel density of the optic nerve head and macula versus structural parameters with optical coherence tomography in pseudoexfoliative glaucoma

PURPOSE

To evaluate the diagnostic ability of the vessel density (VD) of the optic nerve head (ONH) and the macula on optical coherence tomography (OCT) angiography and the retinal nerve layer thickness (RNFL) thickness and the macular ganglion cell complex (GCC) thickness on OCT in patients with pseudoexfoliative glaucoma (PXG).

METHODS

Cross-sectional study including PXG patients and healthy controls. Demographic and clinical data were noted for all participants. Optical coherence tomography (OCT) and OCT angiography (OCTA) images of the ONH and macular area were obtained with the RS-3000 Advance OCT (Nidek Co., Gamagori, Japan). The RNFL and GCC thickness of different sectors was provided by the software. Macular VD of the superficial capillary plexus (SCP) and ONH VD of the radial peripapillary capillary plexus (RPCP) were registered. Groups were compared and area under the receiver operating characteristic (AUROC) curves were used to determine the power of discrimination of each parameter.

RESULTS

RNFL and GCC thickness and ONH and macular VD were significantly lower in PXG patients compared with healthy controls (all, p<0.05). The best discrimination parameter was the average RNFL thickness (AUROC: 0.928). ONH VD AUROC was better than that of macular VD (AUROC: 0.897 and 0.780, respectively). ONH VD AUROC was comparable to RNFL thickness (p<0.001).

CONCLUSIONS

The diagnostic ability of ONH vessel density in PXG appears comparable to that of the structural parameters, RNFL and GCC thickness, obtained with OCT, and may be a valuable tool in clinical practice.

Comparison of peripapillary vascular density as measured by optical coherence tomography angiography between various types of open-angle glaucoma

PURPOSE

The purpose of this study is to compare the peripapillary vascular density in patients with various types of open-angle glaucoma (primary open-angle glaucoma, pseudoexfoliative glaucoma and pigmentary glaucoma) with healthy subjects by optic coherence tomography angiography (OCTA).

METHODS

Twenty-seven eyes with diagnosed POAG, thirty-four eyes with diagnosed PXG, twenty eyes with diagnosed PG and thirty eyes of healthy individuals were included in our study. Peripapillary vessel density measurements were performed with all images; (AI-DD), intra-disc (ID-DD) and peripapillary (PP-DD); measurement of vascular density in the radial peripapillary capillary network was performed by OCTA. The Kruskal-Wallis test and post-hoc test were performed for statistical analysis.

RESULTS

AI-DD was 50.76±2.07% in the healthy group, 47.12±2.57% in POAG, 39.71±6.64% in PXG, and 43.37±1.55% in PG. ID-DD was 50.49±3.74% in the healthy group, 49.51±6.83% in POAG, 38.42±13.46% in PXG, and 40.9±4.45% in PG. PP-DD was 51.26±3.12% in the healthy group, 50.13±3.04% in POAG, 42.31±7.31% in PXG, and 47.6±1.40% in PG. While it was found that all image and intra-disc vascular density measurements were statistically significantly lower in the PG and PXG group compared to the healthy group and the POAG (P<0.001), there was no significant difference between PXG and PG or between the control group and POAG.

CONCLUSIONS

The lower radial peripapillary capillary density in PXG and PG compared to the POAG and healthy groups suggests that the blood flow around the optic disc is negatively affected in these patients.

Optic Nerve Head, Peripapillary and Macular Microvascular Characteristics in Patients With Unilateral Pseudoexfoliation Glaucoma

PRCIS

In unilateral pseudoexfoliation glaucoma (PEXG), there may be decreased choroidal vascularity index (CVI), radial peripapillary capillary plexus' perfusion and flow. CVI may also be reduced in fellow eyes, suggesting that PEXG is bilateral disease.

PURPOSE

Evaluation of peripapillary and macular choroidal microvascularity and radial peripapillary capillary plexus in both eyes with unilateral PEXG and healthy eyes.

MATERIALS AND METHODS

Ninety-six eyes of 48 patients with unilateral PEXG [PEX (+): 48 eyes with PEXG; PEX (-): 48 eyes without PEX] and the right eyes of 45 age- and sex-matched healthy controls were included in the study. CVI was calculated on enhanced depth imaging optical coherence tomography scans. Radial peripapillary capillary vascular layer were evaluated by OCT-angiography.

RESULTS

Macular CVI (mCVI), temporal and nasal peripapillary CVI (pCVI) was significantly decreased in the PEX (+) compared with the PEX (-) and control group ( P <0.05 for all). Although there was a significant difference between PEX (-) and the control group in terms of mCVI and temporal pCVI, there was no significant difference between the 2 groups in terms of nasal pCVI ( P =0.008, P =0.036, and P =0.604, respectively). There was a significant difference in perfusion density (PD) and flux index (FI) between PEX (+) group, PEX (-) group and control group in all quadrants and average value ( P <0.05 for all). Although the PD and FI values in all quadrants and average values of the PEX (-) group were lower than the control group, this difference was not significant.

CONCLUSIONS

CVI in the macula and peripapillary region was significantly decreased in eyes with PEXG. Similarly, PD and FI were lower in eyes with PEXG. Low mCVI and temporal pCVI can also be seen in eyes without PEX.

The Differences in the Pattern of OCT and OCTA Examinations between Early Normal- and High-Tension Pseudoexfoliative Glaucoma

Purpose. The aim of this study was to compare the results of optical coherence tomography angiography (OCTA) and optical coherence tomography (OCT) examinations in patients with normal-tension glaucoma (NTG) in comparison to high-tension pseudoexfoliative glaucoma (HTG) patients at the early stage of glaucoma. Material and methods. The studied groups consisted of patients in the early stage of NTG (70 eyes) and the early stage of HTG (71 eyes). In NTG and HTG groups, a detailed ophthalmic examination was performed. Optic disc OCT with peripapillary RNFL measurements and OCTA examination with the evaluation of the macula and optic disc were performed for all participants using Zeiss Cirrus 5000. Results. NTG and HTG groups were statistically similar as far as the MD was concerned, and both groups had early glaucoma. When evaluating the RNFL thickness, the only statistical difference between early NTG and HTG was observed in the thicknesses in the temporal sector of peripapillary RNFL, with thinner values in the NTG group (53.94 vs. 59.94, p = 0.0071). When the OCTA results of the macula and optic disc were evaluated, there were no statistical differences between early NTG and HTG. Conclusions. The vascular density and flow parameters assessed in OCTA were equal between early NTG and HTG, and therefore the involvement of vascular factors in NTG pathogenesis could not be confirmed. Our results confirm the preponderance of more frequent temporal RNFL involvement in early NTG.

Longitudinal Changes in Peripapillary and Macular Vessel Densities in Glaucomatous Eyes With a Single-Hemifield Retinal Nerve Fiber Layer Defect

PRCIS

The peripapillary vessel density decreased significantly in the affected hemiretina compared with that in the intact hemiretina in glaucomatous eyes with a single-hemifield retinal nerve fiber layer defect.

PURPOSE

To evaluate the difference in the change rates of peripapillary vessel density (pVD) and macular vessel density (mVD) measured using optical coherence tomography angiography (OCTA) in glaucomatous eyes with a single-hemifield retinal nerve fiber layer (RNFL) defect.

MATERIALS AND METHODS

We performed a retrospective, longitudinal study of 25 patients with glaucoma who were followed up for at least 3 years, with a minimum of 4 visits after baseline OCTA. At each visit, all participants underwent OCTA examination, and the pVD, mVD were measured by removing the large vessels. Changes in the pVD, mVD, peripapillary RNFL thickness (pRNFLT), and macular ganglion cell inner plexiform layer thickness were investigated in the affected and intact hemispheres, and the differences between the 2 hemispheres were compared.

RESULTS

In the affected hemiretina, the pVD, mVD, pRNFLT, and mCGIPLT were reduced than that in the intact hemiretina (all, P < 0.001). The changes in pVD and mVD were statistically significant at the 2-year and 3-year follow-ups in the affected hemifield (all, P <0.05). However, pVD and mVD did not show statistically significant changes in the intact hemiretina throughout the follow-up visits. Although the pRNFLT decreased significantly at the 3-year follow-up, the macular ganglion cell inner plexiform layer thickness showed no statistical change at any follow-up visit. Compared with the intact hemisphere, pVD was the only parameter that showed significant changes throughout the follow-up period.

CONCLUSION

Although pVD and mVD decreased in the affected hemiretina, the reduction in pVD was significant compared with that in the intact hemiretina.

Peripapillary and macular vascular parameters by optical coherence tomography angiography in primary congenital glaucoma

OBJECTIVE

To evaluate the differences in peripapillary and macular vascular parameters by optical coherence tomography angiography (OCTA) between patients with primary congenital glaucoma (PCG) and healthy controls; and to determine their diagnostic accuracy.

MATERIAL AND METHODS

Observational, cross-sectional study including 39 eyes with PCG and 78 healthy eyes. Only one eye per patient was included. All included patients underwent a comprehensive ophthalmic examination and peripapillary and macular analysis were performed by AngioplexTM OCTA (Cirrus HD-OCT 5000) with a 4.5 × 4.5 mm optic nerve head scan and 6 × 6 mm macular scan. Global data and quadrant data from peripapillary vascular parameters and global data and circular sectors data from macular superficial plexus parameters were compared between groups. The glaucoma discrimination capability of these parameters was calculated as areas under the receiver operating characteristics curve (AUC ROC).

RESULTS

Mean age was 14.1 ± 8.7 years for the PCG patients and 11.7 ± 6.2 years for controls (p = 0.093). All vascular peripapillary measurements (global and quadrants; all p < 0.001) and all macular measurements (p < 0.042) excepting perfusion density in the inner circle (p = 0.087), were reduced in the PCG group compared to controls. According to AUC ROC, peripapillary (all ≥ 0.706) and macular parameters (all ≥ 0.699) showed good diagnostic capacity. AUC ROC for the most discriminatory measurements corresponding to blood flux index (0.887) and whole macula vascular density (0.855) were similar (p = 0.085).

CONCLUSION

Peripapillary and macular vascular parameters by OCTA are decreased in patients with PCG, showing a good capacity to discriminate between normal and glaucomatous eyes.

Peripapillary and fovea avascular zone optical coherence tomography angiography parameters in exfoliation glaucoma versus primary open-angle glaucoma versus healthy eyes

Purpose

To examine the differences in the peripapillary vascular parameters and foveal-avascular-zone (FAZ) vascularity parameters between primary open-angle-glaucoma (POAG) patients versus exfoliation-glaucoma (XFG) patients versus healthy subjects.

Methods

This is cross-sectional study and a comparative clinical study. POAG and XFG patients and healthy subjects underwent a comprehensive ophthalmic examination, including visual field optical coherence tomography (OCT) and OCT angiography (OCTA) of the optic disc and FAZ. Differences in peripapillary vessel density (VD), perfusion density (PD), and FAZ area and circularity were examined between all groups, as well as correlations between clinical parameters and vascularity parameters for each glaucoma group.

Results

A total of 109 subjects (one eye for each patient) were analyzed, including 45 with POAG, 30 with XFG, and 34 controls. The average peripapillary VDs were the lowest among the XFG patients and the highest among the controls (P < 0.05, ANOVA). The average peripapillary PD of the central ring was the lowest in the XFG group and the highest in the control group (P = 0.02, ANOVA). A significant negative correlation was found between the average peripapillary VDs and PDs of the inner ring and full ring and disease severity of the POAG patients. There was a significant positive correlation between the average peripapillary PDs of the central rings and full ring and the central macular thickness of the XFG patients (P < 0.01 and P < 0.04, respectively, Pearson correlation).

Conclusion

The peripapillary vascular parameters of the POAG and XFG patients were lower compared to those of normal participants. A correlation between clinical characteristics of POAG and XFG patients and PD was found. This may hint to a vascular mechanism in glaucoma either primary or secondary to intra-ocular pressure/OAG damage.

Diagnostic Performance of Optical Coherence Tomography for Pseudoexfoliation Glaucoma

PRECIS

LC thickness and LCCI had comparable diagnostic performances with RNFL thickness in distinguishing eyes with PXG from those with PXS. BMO-MRW showed the lowest diagnostic performance among all geometric parameters derived from OCT scans we evaluated.

OBJECTIVE

To compare the diagnostic performance of different geometric parameters derived from optical coherence tomography (OCT) scans (retinal nerve fiber layer [RNFL] thickness, lamina cribrosa [LC] thickness, LC curvature index [LCCI] and Bruch's membrane opening-minimum rim width [BMO-MRW]) for distinguishing eyes with pseudoexfoliation glaucoma (PXG) from pseudoexfoliation syndrome (PXS) and healthy eyes.

METHODS

Fifty-five eyes of 55 patients with PXG, 55 eyes of 55 patients with PXS, and 50 healthy subjects were enrolled in this cross-sectional study. The areas under the receiver operating characteristic curves (AUCs) of RNFL thickness, LC thickness, LCCI and BMO-MRW were calculated and compared.

RESULTS

In discriminating between eyes with PXG from those with PXS, LC thickness (0.930 [95% CI: 0.883-0.978]) and global RNFL thickness (0.974 [95% CI: 0.947-0.992]) presented comparable AUCs (P=0.244). In distinguishing subjects wiht PXG from healthy controls, both LC thickness (0.972 [95% CI: 0.948-0.997]) and LCCI (0.983 [95% CI: 0.968-0.998]) had comparable AUCs with global RNFL thickness (0.988 [95% CI: 0.974-1.000]) (P=0.094 andP=0.239, respectively). Global BMO-MRW had lower AUCs than RNFL thickness (0.839 [95% CI: 0.759-0.920] and 0.897 [95% CI: 0.836-0.958], respectively) in distinguishing PXG from both PXS and healthy controls (P=0.001 andP=0.002, respectively). BMO-MRW also had significantly lower AUCs than both LC thickness and LCCI in distinguishing PXG from healthy controls (P=0.034 andP=0.001, respectively).

CONCLUSION

LC thickness and LCCI had better diagnostic performance than BMO-MRW in distinguishing PXG from PXS and healthy controls, which were comparable to RNFL thickness.

The Role of Vessel Density as Measured by Optical Coherence Tomography Angiography in the Evaluation of Pseudoexfoliative Glaucoma: A Review of the Literature

INTRODUCTION

To review the existing literature about the optical coherence tomography angiography (OCTA) findings regarding peripapillary and macular vessel density (VD) in patients with pseudoexfoliative glaucoma (PXG).

METHODS

A comprehensive search of the PubMed database was conducted to include articles up to November 1, 2021, using an appropriate search algorithm. The retrieved articles were assessed for eligibility and filtered manually to exclude duplicates, while articles and book chapters cited in the reference lists of the eligible articles obtained by this method were reviewed so as not to miss any relevant studies.

RESULTS

There is consistency among the studies published so far that a significant decrease in peripapillary VD exists in eyes with PXG compared to controls, and macular VD has also been reported to be significantly lower in PXG eyes than controls. However, the existing literature remains controversial regarding OCTA findings in eyes with PXG compared to those with primary open-angle glaucoma (POAG). Several studies have found that peripapillary VD and macular VD were significantly lower in PXG than POAG, while other studies reported no significant difference.

CONCLUSIONS

Eyes with PXG were found to present decreased peripapillary and macular VD compared to control eyes, suggesting that a vascular component, including optic nerve hypoperfusion, may be implicated in the pathogenesis of PXG.

Measuring optic nerve head perfusion to monitor glaucoma: a study on structure-function relationships using laser speckle flowgraphy

PURPOSE

We aimed to describe the global and localized correlations among visual field (VF) sensitivity, optic nerve head (ONH) perfusion measured by laser speckle flowgraphy (LSFG) and neural structure measured by optical coherence tomography (OCT) in open-angle glaucoma (OAG) and to compare the floor effect for LSFG and OCT.

METHODS

Cross-sectional, multicenter study including one eye each from fifty OAG patients (mean age 69.3 years; average VF mean deviation, MD, -8.5 dB, range -25.17 to 0.85 dB) and fifty-one controls. Patients underwent SITA standard 24-2 automated perimetry and measurement of ONH perfusion, peripapillary retinal nerve fibre layer thickness (RNFLT) and macular ganglion cell-inner plexiform layer thickness (GCIPLT). We tested the presence of a significant change (breakpoint) in the correlation slope with VF sensitivity to assess floor effect.

RESULTS

The correlation between the LSFG parameter Mean All (MA) of the global disc area and MD (r = 0.56, p < 0.001) did not show a breakpoint, in contrast to the correlations between MD and OCT global parameters, which showed breakpoints at -8.53 and -4.05 dB for RNFLT and GCIPLT, respectively. Global and localized correlations with VF sensitivity were stronger for LSFG compared to OCT. In particular, LSFG outperformed OCT in the correlation with the central VF sector (r = 0.50, p < 0.001 and r = 0.06, p = 0.67 for MA and RNFLT, respectively).

CONCLUSION

The global and sectoral correlations with VF sensitivity and the favourable floor effect compared to OCT indicate LSFG as a promising tool to monitor progression particularly in late-stage glaucoma. Further longitudinal studies are warranted.

Optic nerve head vessel density in different stages of pseudoexfoliation disease

PURPOSE

To evaluate the superficial vascular density of the optic nerve head in different stages of pseudoexfoliation disease using optical coherence tomography angiography (OCTA).

METHODS

In this cross-sectional study, 57 normal eyes, 41 eyes with pseudoexfoliation syndrome (PXS), 82 eyes with pseudoexfoliation glaucoma (PXG) and 27 non-glaucomatous fellow eyes of PXG (NL-PXG) that had OCTA were included. Circumpapillary RNFL (cpRNFL) thickness and circumpapillary capillary density (cpCD) were compared among the groups after adjusting for confounders using linear-mixed model.

RESULTS

PXG eyes had thinner global RNFL and lower cpCD (74.2±14.3 µm and 36.7±10.0%) than control (103.3±8.6 µm and 52.5±2.3%), PXS (96.8±8.8 µm and 51.5±2.3%), and NL-PXG eyes (96.3±11.1 µm and 50.1±3.9%) (p<0.001). After adjustment for age, gender and signal strength index, global cpRNFL thickness was comparable among control, PXS and NL-PXG. NL-PXG had the lowest cpCD (p=0.045) and sectoral cpCD compared to PXS and control eyes. Although cpCD was comparable between control and PXS (p=0.425) eyes, sectoral differences (p=0.009 and 0.004, for inferonasal and temporal-inferior cpCD, respectively) were detectable between the two groups. AUROC for differentiating NL-PXG eyes from normal were better for cpCD (0.78) compared to cpRNLF (0.69).

CONCLUSIONS

OCTA can detect reduced capillary density before significant changes in cpRNFL in fellow eyes of PXG patients. This can enable earlier detection of glaucomatous loss in pseudoexfoliation disease and enhance management of the disease.

Ganglion cell complex and macular thickness layers in primary open-angle glaucoma, pseudoexfoliation glaucoma and healthy eyes: A comparative study

PURPOSE

To investigate the differences in the ganglion cell complex (GCC) and macular thickness measurements between primary open-angle glaucoma (POAG), pseudoexfoliation glaucoma (PXG), and healthy eyes with optical coherence tomography (OCT)optovue.

METHODS

In this non-randomized comparative cross-sectional study, 43 healthy eyes, 68 POAG eyes, and 57 PXG eyes were included. Patients were matched for age and disease severity. OCT angiography images were obtained for automated measurement of the GCC and macular thickness layers (inner and outer).

RESULTS

All GCC parameters were significantly difference between healthy and glaucomatous eyes (mild, and moderate to severe disease).There were no significant differences in GCC parameters between POAG and PXG patients except focal loss volume (FLV) after adjustment. Moderate to severe PXG eyes exhibited significantly lower GCC, larger global loss volume (GLV) values, and FLV values when compared with mild PXG eyes (p<= 0.05). We found significant thinning patterns in inner retinal thickness (fovea, parafovea, and perifovea), and total retinal thickness (parafovea, and perifovea) in moderate to severe PXG eyes when comparing with POAG eyes. Patients with moderate to severe PXG also showed significantly thinning patterns in inner retinal layers (fovea, parafovea and perifovea) and total retinal thickness (nasal parafovea) in compared to mild PXG.

CONCLUSION

It appears that GCC thickness is not significantly different between POAG and PXG except FLV. Despite similar retinal thickness in mild disease, a significant reduction in total and inner retinal thickness was demonstrated in moderate to severe PXG compared to moderate to severe POAG, in fovea, parafovea and perifovea region.

Macular, papillary and peripapillary perfusion densities measured with optical coherence tomography angiography in primary open angle glaucoma and pseudoexfoliation glaucoma

Purpose

To compare the blood flow situation in primary open-angle glaucoma (POAG) and pseudoexfoliation glaucoma (PXG) using optical coherence tomography angiography (OCTA).

Methods

In this prospective study a total of 26 POAG and 23 PXG eyes were included. All patients underwent a complete ophthalmological examination including standard automated perimetry, stereoscopic photographs of the optic disc, peripapillary retinal nerve fibre layer analysis and examination of vascular parameters of the optic nerve head (ONH), the peripapillary region and macula using OCTA. In addition to the vascular parameters recorded by the device, the vascular images were graphically evaluated using Image J. All recorded vascular parameters were compared between both groups and correlated to structural and functional parameters.

Results

The mean superficial perifoveal plexus perfusion density (PD) was significantly lower in PXG eyes than compared to POAG eyes using OCTA (32.57% ± 3.57% vs. 34.92% ± 2.11%, p = 0.007). The mean PD parameters for the superficial peripapillary plexus (40.98% ± 3.04% vs. 42.09% ± 2.29%, p = 0.152) as well as the size of the foveal avascular zone (FAZ) (0.23 mm² ± 0.1 mm² vs. 0.23 mm² ± 0.09 mm²) did not differ between both groups. Additional graphic evaluation using Image J showed no significant difference for superficial perifoveal plexus PD (32.97% ± 1.11% vs. 33.35% ± 0.95%, p = 0.194) and peripapillary plexus PD (46.65% ± 0.83% vs. 46.95% ± 0.5%, p = 0.127) between the groups. Retinal nerve fibre layer (RNFL) thickness correlated significantly with peripapillary plexus PD for both OCTA data and Image J data (p < 0.001, p = 0.032).

Conclusion

The severity of the glaucoma seems to be crucial for peripapillary and macular perfusion densities, and not the form of glaucoma. An additional graphic evaluation is a possible step that could be implemented to improve the comparability of OCTA scans and to optimize the possibility of quantitative perfusion analysis in the case of deviating quality criteria.

Analysis of the choroidal vascularity in asymmetric pseudoexfoliative glaucoma using optical coherence tomography-based image binarization

PURPOSE

To analyse choroidal vascular properties using an image binarization tool in patients with asymmetric pseudoexfoliative glaucoma (PXG) and compare them with healthy individuals.

METHODS

This cross-sectional study included 144 eyes of 96 patients. The eyes were divided into three groups: 48 glaucomatous eyes and 48 non-glaucomatous contralateral eyes with no clinically observable pseudoexfoliation material of patients with asymmetric PXG, and 48 control eyes. Enhanced depth imaging optical coherence tomography scans of the macula and 3.4-mm diameter, 360-degree circle scans of the optic nerve head were binarized using ImageJ software (National Institutes of Health, Bethesda, MD, USA). The choroidal vascularity index (CVI) was calculated as the ratio of the luminal area to the total circumscribed choroidal area.

RESULTS

The macular CVI (mCVI) was significantly lower in the glaucomatous eyes than in the fellow eyes (p = 0.007) and the control eyes (p = 0.001). The peripapillary CVI (pCVI) in all sectors was significantly lower in the glaucomatous eyes than in the other two groups (all p < 0.05). Non-glaucomatous fellow eyes had lower CVI values in the macula and in the peripapillary region, except for the superior-nasal and nasal sectors, compared to the control eyes (all p < 0.05). In multivariate regression analysis, while the cup-to-disc ratio was negatively associated with the pCVI, AL was negatively associated with the mCVI in both eyes of patients with PXG.

CONCLUSIONS

CVI was decreased in the macula and peripapillary area in glaucomatous eyes. Furthermore, the CVI tended to decrease in non-glaucomatous fellow eyes of PXG patients. This finding may suggest subclinical involvement and require further exploration into the pathogenesis of glaucoma.

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.

Optical Coherence Tomography and Glaucoma

Early detection and monitoring are critical to the diagnosis and management of glaucoma, a progressive optic neuropathy that causes irreversible blindness. Optical coherence tomography (OCT) has become a commonly utilized imaging modality that aids in the detection and monitoring of structural glaucomatous damage. Since its inception in 1991, OCT has progressed through multiple iterations, from time-domain OCT, to spectral-domain OCT, to swept-source OCT, all of which have progressively improved the resolution and speed of scans. Even newer technological advancements and OCT applications, such as adaptive optics, visible-light OCT, and OCT-angiography, have enriched the use of OCT in the evaluation of glaucoma. This article reviews current commercial and state-of-the-art OCT technologies and analytic techniques in the context of their utility for glaucoma diagnosis and management, as well as promising future directions. Expected final online publication date for the Annual Review of Vision Science, Volume 7 is September 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Automated Evaluation of Parapapillary Choroidal Microvasculature in Pseudoexfoliation Syndrome and Pseudoexfoliation Glaucoma

OBJECTIVE

To determine whether parapapillary choroidal microvasculature (PPCMv) density as measured by optical coherence tomography angiography differs between pseudoexfoliation syndrome (PXS) and pseudoexfoliation glaucoma (PXG).

DESIGN

Cross-sectional study.

METHODS

One hundred ninety-two eyes of 120 subjects from 2 academic referral institutions were enrolled. Automated PPCMv density was calculated using custom Matlab software in inner and outer annuli around the optic nerve region in addition to peripapillary superficial vasculature. Linear modeling was used to compare vessel densities among groups.

RESULTS

Data from 64 eyes with PXS, 84 eyes with PXG, and 44 eyes healthy control subjects were analyzed. The differences of visual field mean deviation and peripapillary retinal nerve fiber layer thickness among study groups were statistically significant with lower values in PXG eyes compared with the PXS and control groups. Peripapillary superficial retinal vessel densities were significantly reduced in patients with PXG compared with patients with PXS and normal control subjects (all P < .001) without a difference between PXS and control eyes. Customized outer annular PPCMv density in the PXG group with a value of 11.1% (SD 5.1%) was lower than that in PXS with a value of 13.2% (SD 5.3%; P = .001). Similarly, PXS values were lower than those of control eyes with a value of 18.6% (SD 5.1%; P < .001).

CONCLUSION

A progressive decrease in outer PPCMv from the control group to those with PXS without glaucoma to those with PXS and glaucoma (PXG) showed deep peripapillary vasculopathy in pseudoexfoliation syndrome. Choroidal vessel density may be affected early in the course of pseudoexfoliation before glaucoma develops.

Comparison of Peripapillary Choroidal Microvasculature Dropout in Primary Open-angle, Primary Angle-closure, and Pseudoexfoliation Glaucoma

PRECIS

The prevalence of choroidal microvascular dropout (CMvD) was significantly higher in primary open-angle glaucoma (POAG) than primary angle-closure glaucoma (PACG) or pseudoexfoliation glaucoma (PXG) in the early stage. However, in the advanced stage, it did not differ among the 3 groups.

PURPOSE

The purpose of this study was to compare the prevalence of peripapillary CMvD in POAG, PACG, and PXG.

MATERIALS AND METHODS

The presence of peripapillary CMvD was identified using optical coherence tomography angiography (AngioVue/RTVue-XR) imaging of the choroid in 186 eyes from 186 subjects [age and visual field (VF) mean deviation (MD) matched; 62 POAG, 62 PACG, and 62 PXG eyes]. Prevalence of CMvD was compared among glaucoma types in early and moderate to advanced disease, as divided by VF MD (-6 dB). The association between glaucoma type and presence of CMvD was evaluated using logistic regression analysis.

RESULTS

Prevalence of CMvD was significantly different between glaucoma types in early-stage disease (PACG 7.5%, PXG 25%, and POAG 46.3%, P<0.001), but it did not differ between glaucoma types in eyes with moderate to advanced disease (PACG 59.1%, PXG 68.2%, and POAG 81%; P=0.331). After adjusting for age, sex, the β-zone peripapillary atrophy/disc ratio, and glaucoma severity (VF MD), the CMvD odds ratio was 7.50 times greater in POAG than in PACG (P=0.001).

CONCLUSIONS

CMvD was more common in POAG relative to both PACG and PXG, especially in early-stage disease. This finding suggested a role for ischemic injury in the pathogenesis of POAG.

Peripapillary and Macular Vessel Density Measurement With Optical Coherence Tomography Angiography in Exfoliation Syndrome

PRECIS

Although peripapillary retinal nerve fiber layer thickness (RNFLTs) and vessel density (VD) values were similar to healthy group, eyes with exfoliation syndrome had significantly lower superficial macular VDs and minimum ganglion cell analysis values.

PURPOSE

To compare peripapillary and macular perfused capillary densities with optical coherence tomography angiography (OCT-A) between patients with eyes having exfoliation syndrome (XFS) and normal age-matched healthy controls.

PATIENTS AND METHODS

This cross-sectional study included patients diagnosed with XFS from December 2017 to January 2020 at the Glaucoma Department. Peripapillary and parafoveal superficial VDs were obtained using OCT-A. The RNFLTs and ganglion cell analysis values were compared.

RESULTS

Thirty-nine eyes of 39 XFS patients (26 women; mean age, 69.0±8.1 y) and 39 eyes of 39 healthy patients (25 women; mean age, 68.0±8.6 y) were enrolled. There were no statistically significant differences in sex or age distribution, central corneal thickness measurements, refractive errors, or intraocular pressures between both groups (all P>0.05). There were no statistically significant differences in the peripapillary VD or peripapillary RNFLT between XFS eyes and healthy eyes (P>0.05 for all). In the macular region, most superficial VD parameters were significantly reduced in the XFS group (P=0.02 for parafoveal VD, P=0.04 for both hemifields). While the average ganglion cell and internal plexiform layer (GCL+IPL) values were similar between groups (P=0.19), the minimum GCL+IPL value was lower in the XFS group than in the healthy group (P=0.03).

CONCLUSION

Although structural test results, especially peripapillary RNFLT and mean GCL+IPL, were similar between the healthy and XFS groups, macular VD values were lower in XFS eyes. Our findings implicate microvascular damage can be the mechanism underlying XFS-related changes and indicate that it precedes significant structural damage.

Peripapillary and Macular Vessel Density Measurement by Optical Coherence Tomography Angiography in Pseudoexfoliation and Primary Open-angle Glaucoma

PRECIS

Pseudoexfoliation glaucoma eyes had a similar level of peripapillary and superficial macular vessel densities compared with primary open-angle glaucoma eyes matched for age and glaucoma severity when assessed by optical coherence tomography angiography (OCT-A).

PURPOSE

To compare vessel density (VD) measured by OCT-A between primary open-angle glaucoma (POAG) and pseudoexfoliation glaucoma (PXG) in the peripapillary and macular areas.

MATERIALS AND METHODS

The circumpapillary (cpVD), parafoveal (pfVD), and perifoveal vessel densities (perifVD) were obtained using OCT-A (AngioVue/RTVue-XR) in 98 eyes from 98 subjects [age, visual acuity, visual field (VF) mean deviation (MD) matched 49 POAG and 49 PXG eyes]. Global and 8 sectoral VDs in the peripapillary capillary layer were compared. In the macula, the superficial and deep layers of the pfVD and perifVD were analyzed globally and in 4 quadrants. Univariate and multivariate linear regression models were built using cpVD, pfVD, and perifVD as dependent variables and covariates [age, intraocular pressure (IOP), axial length, signal strength index (SSI), and retinal nerve fiber layer (RNFL) thickness] were considered independent variables.

RESULTS

In the peripapillary region, none of the VDs differed between groups both before and after adjustment. When we adjusted superficial and deep layer macular VDs for age, IOP, SSI, axial length, and RNFL thickness, all of which could affect measurements, the 2 groups did not differ in any sector. The cpVD in POAG eyes significantly correlated with VF MD and RNFL thickness, whereas IOP, VF MD, and RNFL thickness affected cpVD in PXG. The macular VD in the deep layer was associated with only SSI in both groups.

CONCLUSIONS

Age-matched and glaucoma severity-matched PXG and POAG did not significantly differ in cpVD or in most of the superficial macular VD parameters.

Optical Coherence Tomography Angiography in Glaucoma

Optical coherence tomography angiography (OCTA) is a relatively new, noninvasive, dye-free imaging modality that provides a qualitative and quantitative assessment of the vasculature in the retina and optic nerve head. OCTA also enables visualization of the choriocapillaris, but only in areas of parapapillary atrophy. With OCTA, the movement of red blood cells is used as a contrast to delineate blood vessels from static tissues. The features seen with OCTA in eyes with glaucoma are reduction in the superficial vessel density in the peripapillary and macular areas, and complete loss of choriocapillaris in localized regions of parapapillary atrophy (called deep-layer microvascular dropout). These OCTA changes correlate well topographically with the functional changes seen on visual field examination and structural changes seen on optical coherence tomography (OCT) (ie, parapapillary retinal nerve fiber layer changes and inner retinal layer thickness changes at macula). The OCTA measurements also have acceptable test-retest variability and well differentiate glaucomatous from normal eyes. OCTA measurements can be affected by various subject-related, eye-related, and disease-related factors. Vessel density reduction on OCTA reaches a base level (floor) at a more advanced disease stage than the structural changes on OCT and therefore has the potential to monitor progression in eyes with advanced glaucomatous damage. OCTA also adds information about glaucoma patients at risk of faster progression. OCTA, therefore, complements visual field and OCT examinations to diagnose glaucoma, detect progression, and assess risk of progression.

Optical coherence tomography angiography in glaucoma

Assessment of the vasculature within the optic nerve, peripapillary superficial retina, macula, and peripapillary choroid can be determined in glaucoma using optical coherence tomography angiography (OCTA). Decreased perfusion within the pre-laminar layer of the optic nerve has been correlated with glaucoma severity. The peripapillary superficial retinal vessel density allows diagnosis and detection of glaucoma progression in a manner similar to the peripapillary retinal nerve fiber layer (RNFL) thickness. Furthermore, decreased peripapillary vessel density of the intact hemiretina or unaffected eye of glaucomatous eyes suggests that vascular changes can occur prior to detectable visual field damage. The accuracy for glaucoma detection of the macular ganglion cell (MGC) thickness compared to macular vessel density has differed among studies. Several studies have reported reduction of macular vessel density as well as its ganglion cell thickness. Results of studies evaluating the parapapillary choroid have shown a greater prevalence of choroidal microvasculature dropout in glaucomatous eyes with a parapapillary gamma zone, which is associated with central visual field defects or glaucoma progression. It remains unclear whether the reduced vessel density in glaucoma is a primary event or secondary to glaucomatous damage. Further studies are warranted to elucidate this question.

Comparison of vessel density in macular and peripapillary regions between primary open-angle glaucoma and pseudoexfoliation glaucoma using OCTA

PURPOSE

The aim of our study was to compare macular and peripapillary vessel density using optical coherence tomography angiography (OCTA) between eyes with primary open-angle glaucoma (POAG) and pseudoexfoliation glaucoma (PXG).

METHODS

Thirty-six POAG and 34 PXG eyes with similar visual field defect (no statistically significant difference between average mean deviation and pattern standard deviation scores) were included. Macular superficial vessel density (msVD) in the superficial macular layer and foveal avascular zone (FAZ) parameters were assessed with (6 × 6 mm) and peripapillary vessel density (ppVD) in the radial peripapillary capillary (RPC) with (4.5 × 4.5 mm) OCTA scans. Area under the receiver operating curve was used for assessing diagnostic capability.

RESULTS

In PXG group, all msVD parameters had lesser values, and especially in parafoveal region, statistically significant decrease was shown (p = 0.008) in all subdivisions except nasal (p = 0.053). FAZ area was more larger in PXG [0.32(0.25-0.36)] than POAG [0.28(0.22-0.39)],(p = 0.944). FAZ density - 300 μm had statistically significant decrease in PXG (47.22 ± 6.92) according to POAG groups (50.63 ± 7.25) (p = 0.048). Most of RPC VD parameters had decreasing values in PXG group (p > 0.05). VDs and corresponding thicknesses had significant remarkable positive correlation in both macular and peripapillary regions. Significant remarkable negative correlations were observed between fovea VD and FAZ area, FAZ perimeter and between fovea thickness and FAZ area, FAZ perimeter.

CONCLUSION

PXG eyes were found to have lesser values in terms of VD in the macular area, especially in the parafoveal and FD-300 regions, compared to POAG eyes which had similar functional and structural glaucomatous damage. Patients whose etiology was PXG and who seemed to have the same functional damage as those with POAG were actually found to have greater macular vascular damage. In addition, it was observed that macular vascular parameters correlated with peripapillary vascular parameters.

Evaluation of Diurnal Fluctuation in Parafoveal and Peripapillary Vascular Density Using Optical Coherence Tomography Angiography in Patients with Exfoliative Glaucoma and Primary Open-Angle Glaucoma

PURPOSE

To determine the diurnal variations in parafoveal and peripapillary vessel density using optical coherence tomography angiography in patients with exfoliative glaucoma, patients with primary open-angle glaucoma and healthy individuals.

MATERIALS AND METHODS

In this prospective cross-sectional study, 36 exfoliative glaucoma patients, 34 primary open-angle glaucoma patients and 35 healthy individuals were examined. Optical coherence tomography angiography was used for examining the vessel density of peripapillary (radial peripapillary capillary) and parafoveal (superficial layer) regions. Optical coherence tomography angiography readings were obtained at 09:00, 11:00, 14:00 and 16:00 on the same day. Intraocular pressure values were assessed accordingly. The intraclass correlation coefficients were used to evaluate test-retest variability.

RESULTS

Diurnal variation in intraocular pressure or vessel density values was not found in any parafoveal or peripapillary region in any of the groups at any hour of measurement. The vessel density in the temporal sector of the exfoliative glaucoma group was significantly lower than in the primary open-angle glaucoma group at all time points. (Mann-Whitney U test; 09:00, P= .015; 11:00, P= .002; 14:00, P= .040; and 16:00, P= .048, respectively). The test-retest repeatability was high and almost excellent for the parafoveal and peripapillary regions in each group (XFG range: 0.757 - 0.985, POAG range: 0.834 - 0.985, and control range: 0.708 - 0.983).

CONCLUSIONS

It may be important to estimate the diurnal fluctuation occurring in retinal haemodynamics in patients with exfoliative glaucoma and primary open-angle glaucoma despite the lack of any considerable variation in intraocular pressure and retinal vessel density values in one day. The study found that at any point of time, vessel density of radial peripapillary capillary in temporal region was lower in exfoliative glaucoma patients than in primary open-angle glaucoma patients having the same glaucoma severity.

Optical coherence tomography angiography of the peripapillary region and macula in normal, primary open angle glaucoma, pseudoexfoliation glaucoma and ocular hypertension eyes

AIM

To evaluate and compare the peripapillary and retinal vasculature changes in primary open angle glaucoma (POAG), pseudoexfoliation glaucoma (PXG), ocular hypertension (OHT) and normal eyes using optical coherence tomography angiography (OCTA).

METHODS

A total of 114 POAG, PXG and OHT eyes of 60 patients and 46 eyes of 23 healthy control participants with good quality OCTA images were included. The PXG, POAG, OHT, and control groups (aged 68.17±6.30y, 61.11±10.26y, 58.1±8.9y, and 56.9±4.6y, respectively) contained of 46, 36, 32, and 46 eyes, respectively. Measurements of vessel density (VD) in the peripapillary region and macula, average retinal inner thickness, and retinal nerve fiber layer thickness (RNFLT) were compared among groups. In order to test the accuracy of differentiation between eyes with and without glaucoma, the area was calculated under the receiver operating characteristic (ROC) curves.

RESULTS

The VD in glaucomatous eyes was significantly lower than the control group in all peripapillary sectors (44.35%±6.78% vs 50.47%±1.83%, P<0.001), the superficial (44.08%±5.46% vs 51.28%±2.85%, P<0.001) and the deep (45.13%±8.55% vs 54.20%±5.44%, P<0.001) vascular plexus. There was a significant difference in peripapillary VD between glaucomatous and OHT eyes (44.35%±6.78% vs 49.86%±2.45%, P<0.001). The OHT group featured a lower superficial (48.06%±4.32% vs 51.28%±2.85%, P=0.027) and deep plexus (48.70%±5.99% vs 54.20%±5.44%, P=0.013) whole image vessel density (wiVD) than did the control group. The average macular superficial plexus wiVD was significantly lower in eyes with PXG than in eyes with POAG (42.22%±5.36% vs 46.54%±5.56%, P=0.046).

CONCLUSION

OCTA can measure reduced peripapillary and macular VD in eyes with glaucoma and OHT, and these results are correlated to functional and structural glaucomatous alterations. Peripapillary and macular superficial plexus VD is lower in eyes with PXG than in eyes with POAG. Furthermore, the OHT eyes demonstrate impaired macular vasculature in both superficial and deep plexus.

Evaluation of the optic nerve head vessel density in the patients with asymmetric pseudoexfoliative glaucoma: an OCT angiography study

PURPOSE

To evaluate vascular microcirculation changes of the optic nerve head (ONH) in the patients with asymmetric pseudoexfoliative glaucoma (XFG) using optical coherence tomography angiography (OCTA) and to compare vessel density (VD) results with healthy individuals.

METHODS

This prospective study enrolled 120 eyes in total. The eyes were divided into 3 groups: 40 glaucomatous and 40 non-glaucomatous fellow eyes without clinically pseudoexfoliation material (XFM) of patients with asymmetric XFG, and 40 healthy eyes as controls. The optic disc region was evaluated with OCTA (Optovue, Inc., Fremont, CA). VD was assessed as the ratio of the area formed by the vessels in 3 different regions: (1) inside disc; (2) in the peripapillary area defined as a 1-mm wide elliptical annulus around the disc; and (3) in the whole image defined as a 4-mm wide papillary region.

RESULTS

There were significant decreases in VD values of all regions in XFG eyes compared to fellow and control eyes (p < 0.05 for all comparisons). The mean VD values of peripapillary area and whole image were lower in the non-glaucomatous fellow eyes compared with control eyes (p = 0.011 and p = 0.015, respectively). The receiver operating characteristic analysis for differentiating fellow eyes from healthy eyes had highest area under the curve and sensitivity at 90% specificity for superior-hemi (0.811, 65.2%), followed by ppVD (0.775, 61.8%) and whole image (0.743, 55.9%).

CONCLUSIONS

OCTA as a novel imaging may be a valuable structural test in diagnosis and follow-up of glaucoma.

Quantitative analysis of radial peripapillary capillary plexuses in patients with clinically unilateral pseudoexfoliation syndrome

PURPOSE

The aim of this study was to image the radial peripapillary capillary vessel densities (RPCvds) of the affected eyes and fellow unaffected eyes of individuals with unilateral pseudoexfoliation syndrome (PES) using optical coherence tomography angiography (OCTA) and to compare the RPCvds with those of normal age-matched individuals.

METHODS

The eyes were divided into three groups: the pseudoexfoliative material (PXM)-positive eyes of patients with clinically unilateral PES (study eyes), the fellow eyes of the PXM-positive patients (fellow eyes), and the eyes of healthy patients (control eyes). Those patients with glaucomatous findings, including peripapillary hemorrhaging, cupping, notching, focal thinning of the neuroretinal rim, or intraocular pressure readings greater than 21 mmHg, were excluded from the study. The RPCvd (%), peripapillary retinal nerve fiber layer (RNFL) thickness (μm), cup/disc area ratio, rim area (mm²), disc area (mm²), and cup volume (mm³) were automatically calculated via OCTA.

RESULTS

This cross-sectional comparative prospective study included 128 eyes of 88 patients: 40 PXM-positive eyes, 40 fellow eyes, and 48 control eyes. The RPCvds and RNFL thicknesses in the peripapillary region were significantly lower in the study eyes than in the fellow eyes and the control eyes (p = 0.011 and p = 0.011, p = 0.009 and p = 0.004, respectively). There were no significant differences between the fellow eyes and the control eyes with regard to the RPCvd and RNFL values in any region (p > 0.05 for all).

CONCLUSION

Lower RPCvds could provoke capillary deficiency and deterioration of the perfusion of the optic nerve head in patients with PES.

Choroidal Microvascular Dropout in Pseudoexfoliation Glaucoma

Purpose

To compare the prevalence of choroidal microvasculature dropout (CMvD) in pseudoexfoliation glaucoma (PXG) and disease severity–matched primary open-angle glaucoma (POAG) eyes.

Methods

In a cross-sectional study, 39 eyes with PXG (33 patients) and 39 glaucoma severity–matched POAG eyes (34 patients) underwent visual fields, optical coherence tomography and optical coherence tomography angiography examination. Peripapillary vessel density (VD) was evaluated from the radial peripapillary capillary slab, parafoveal VD was measured on the superficial vascular plexus slab of the macula, and CMvD was evaluated on the choroidal slabs of the optic disc scan.

Results

The PXG and POAG groups were similar with respect to average mean deviation on visual fields (−12.1 vs. −12.0 decibel, P = 0.96) and average peripapillary retinal nerve fiber layer thickness on optical coherence tomography (71 vs. 74 μ, P = 0.29). Average peripapillary superficial VD (49.7% vs. 51.3%, P = 0.35) and parafoveal VD (44.8% vs. 45.8%, P = 0.33) were similar between the PXG and POAG groups. CMvD was seen in 18 PXG and 31 POAG eyes (46.2% vs. 79.5%, P = 0.002). On multivariate analysis that accounted for the severity of glaucoma, the odds of CMvD was significantly lower in the PXG group when compared with the POAG group (odds ratio: 0.18–0.21, P < 0.01).

Conclusions

The prevalence of CMvD was significantly lower in the PXG eyes when compared with the POAG eyes.

Impact of Binarization Thresholding and Brightness/Contrast Adjustment Methodology on Optical Coherence Tomography Angiography Image Quantification

PURPOSE

Binarization is a critical technique in optical coherence tomography angiography (OCTA) image analysis, but there is no consistency in the method used in published OCTA studies. This study assessed whether differences in OCTA binarization and brightness and contrast adjustments affect quantification measurements.

DESIGN

Prospective cross-sectional validity study.

METHODS

This was a single-center study examining 21 eyes of 11 healthy individuals. All eyes were imaged using a swept-source OCTA (Zeiss), and quantitative measurements resulting from five binarization thresholding and five brightness/contrast adjustment methods were compared. All measurements were calculated for the superficial plexus and choriocapillaris (CC), as well as unaveraged and averaged en face OCTA images.

RESULTS

There were statistically significant differences between measurements from different binarization thresholding methods (P < 0.0001), as well as measurements from different histogram adjustments (P < 0.0001). The binarization thresholds yielded different measurements when combined with variable brightness/contrast adjustments. The method of analysis also affected the directionality of trends in imaging measurements between unaveraged and averaged CC images.

CONCLUSIONS

The method of OCTA image binarization thresholding and histogram adjustment significantly alters quantitative measurements and the directionality of trends. Results obtained from different OCTA binarization methods should be seen as valid only for that given method. This has significant consequences for clinical trials using OCTA measurements as outcome measurements. A consensus is needed across the research community for a consistent method for OCTA image quantification and greater attention paid to fully describing methods in published studies.

Macula Vessel Density and Foveal Avascular Zone Parameters in Exfoliation Glaucoma Compared to Primary Open-Angle Glaucoma

Purpose

The purpose of this study was to explore macula vessel density and foveal avascular zone (FAZ) parameters in exfoliation glaucoma (XFG) compared to primary open-angle glaucoma (POAG) using optical coherence tomography angiography (OCTA).

Methods

This was a cross-sectional observational study. Twenty-six XFG and 28 POAG patients with comparable visual field defects on Humphrey 24-2 and 10-2 perimetries were recruited. OCTA scans (3 × 3 mm) centered on the fovea were obtained. Built-in software was used to measure superficial capillary plexus (SCP) vessel density at different quadrants of the macula. Custom software was then used to create a full-thickness image. The FAZ was manually delineated, and large vessels were removed. Vessel density in eight concentric rings with increments of 200-μm diameters from the delineated FAZ was measured. FAZ parameters were calculated using the custom software.

Results

SCP density was significantly lower in the superior (mean difference [MD] = -4.32, 95% confidence interval [CI] = -7.02, -1.61, P = 0.003) and nasal (MD = -3.00, 95% CI = 05.22, -0.77, P = 0.010) quadrants in XFG versus POAG. SCP vessel density using the concentric ring approach revealed significantly decreased values at all eight rings in XFG versus POAG. In the full-thickness analysis, density was significantly less in the XFG group in all rings except the initial 200 μm. No significant differences existed in FAZ parameters between the groups.

Conclusions

Despite the presence of comparable central visual field defects, the macula vessel density was predominately lower in XFG compared with POAG in our sample of patients. Further studies are warranted to investigate the consistency of our results.