Factors affecting corneal deformation amplitude measured by Corvis ST in eyes with open-angle glaucoma.

PURPOSE: To evaluate the factors affecting corneal deformation amplitude (DA) measured using Corvis ST in eyes with open-angle glaucoma. METHODS: This prospective, longitudinal study included 48 eyes with open-angle glaucoma who required additional intraocular pressure (IOP)-lowering drops. All eyes underwent a complete eye examination at baseline, including a Corvis ST, which was repeated 4-8 weeks after the change in therapy. Factors affecting the corneal biomechanics, namely the DA, were determined using mixed effect models. RESULTS: The mean age of the cohort was 65.0 ± 7.9 years. The mean IOP reduced from 23.4 ± 5.4 mmHg to 17.9 ± 5 mmHg after the change in glaucoma treatment ( P < 0.001). The DA increased from 0.89 ± 0.16 mm to 1.00 ± 0.13 mm after IOP reduction ( P < 0.001). On mixed effect model analysis, IOP (-0.02 ± 0.001, P < 0.001) and corneal pachymetry (-0.0003 ± 0.0001, P = 0.02) affected the change in the DA. CONCLUSION: IOP and corneal pachymetry affect the DA and must be accounted for when using Corvis ST to evaluate corneal biomechanics in glaucoma.

The Importance of Signal Strength Index in Optical Coherence Tomography Angiography: A Study of Eyes with Pseudoexfoliation Syndrome.

Purpose: To evaluate the effect of the signal strength index (SSI) on a comparison of the vascular and structural OCT measurements between eyes with pseudoexfoliation syndrome (PXF) and healthy controls of Asian-Indian origin. Methods: In this cross-sectional study, 33 eyes of 33 PXF patients and 40 healthy eyes of 40 controls underwent OCT and OCT angiography (OCTA). Eyes with intraocular pressure (IOP) >21mmHg, glaucomatous disc changes, or any other ocular pathology were excluded. Peripapillary vessel density (VD) and retinal nerve fiber layer (RNFL) thickness were determined from the optic disc scans. Parafoveal VD and ganglion cell complex (GCC) thickness were measured from the macular scans. These parameters were compared between the groups using mixed effect models after adjusting for clinical confounders such as IOP, as well as SSI of the scans. Results: The 2 groups were demographically similar. Average RNFL (94µm vs 100µm, p = 0.01) and GCC (91µm vs 95µm, p = 0.03) were thinner in the PXF group compared to controls. The average peripapillary VD appeared lower in the PXF groups compared to controls (58.2% vs 58.8%, p = 0.04), but after adjusting for IOP and SSI, no difference was noted (p = 0.39). After accounting for confounders, parafoveal VD in the PXF group was significantly lower compared to controls (44.3% vs 46.8%, p = 0.008). Conclusion: Peripapillary RNFL thickness, parafoveal GCC thickness and parafoveal VD were decreased in eyes with PXF when compared to controls. VD measurements are associated with the SSI and, therefore, clinicians and researchers evaluating OCTA scans quantitatively must consider the SSI value during analysis and interpretation.

Progressive Vessel Density Reduction on OCT Angiography in Glaucoma Eyes with Disc Hemorrhages.

PURPOSE: To identify longitudinal changes in peripapillary and parafoveal vessel density (VD) measured by OCT angiography (OCTA) in primary open-angle glaucoma (POAG) eyes with disc hemorrhages (DHs). DESIGN: Prospective cohort study conducted from August 2016 through August 2020 PARTICIPANTS: Eighteen Asian-Indian participants with POAG (18 eyes) who sought treatment at the clinic with a single DH in the peripapillary region were recruited consecutively. METHODS: The study was conducted at a tertiary eye care center. All participants who were recruited underwent a baseline OCT and OCTA, which were repeated every 4 to 6 months. MAIN OUTCOME MEASURES: Peripapillary VD and retinal nerve fiber layer (RNFL) thickness, parafoveal VD and ganglion cell-inner plexiform layer (GCIPL) thickness in the DH sector, and the corresponding mirror-image sector across the horizontal meridian (control) were evaluated over time using linear mixed-effects models. RESULTS: The baseline average RNFL thickness was 79 ± 9 µm. Mean duration of follow-up was 2.6 ± 0.7 years. In the DH sector, all VD and structural parameters showed a significant negative slope (P < 0.01). In the control sector, the slopes of the structural parameters (RNFL and GCIPL thickness) were not significant (P > 0.05), but the rate of change of the peripapillary and parafoveal VDs were significant (P < 0.01). The rate of change of peripapillary VD was greater in the DH sector compared with the non-DH sector (-2.86 ± 0.6%/year vs. -1.71 ± 0.7%/year; P < 0.01). However, the parafoveal VD slopes did not differ significantly between DH and control sectors (-2.9 ± 0.17%/year vs. -2.8 ± 0.8%/year; P = 0.51). CONCLUSIONS: Eyes with POAG harboring a DH showed not only progressive RNFL and GCIPL loss in the DH sector, but also progressive peripapillary and parafoveal VD reduction in the DH and non-DH regions as documented on OCTA.

Optical Coherence Tomography Angiography and Visual Field Progression in Primary Angle Closure Glaucoma.

PRECIS: Lower whole enface disc (coefficient: 0.02, P=0.03) and macular vessel densities (coefficient: 0.04, P=0.02) on optical coherence tomography angiography (OCTA) were significantly associated with faster rate of mean deviation (MD) decline. PURPOSE: To evaluate the association between OCTA features and prior visual field (VF) progression in primary angle closure glaucoma (PACG). METHODS: In a cross-sectional study, 46 eyes of 31 PACG patients with 5 reliable VF examinations performed over ≥3 years of follow-up underwent OCTA imaging. Effect of clinical (age, sex, number of antiglaucoma medications, mean, and SD of intraocular pressure during follow-up), optical coherence tomography (average retinal nerve fiber layer and ganglion cell complex thickness) and OCTA (whole enface vessel density of disc and macular scan, deep-layer microvascular dropout) parameters on the rate of MD change was evaluated using linear mixed models. RESULTS: Average (±SD) MD of the baseline VF was -7.4±7.3 dB, and rate of MD change was -0.32±0.29 dB/y. Whole enface vessel density of disc and macular scans was 39.5%±8.1% and 38.7%±4.4%, respectively. Microvascular dropout was noted in 33.3% of the eyes. Multivariate mixed models showed that lower whole enface disc (coefficient: 0.02, P=0.03) and macular vessel densities (coefficient: 0.04, P=0.02) were significantly associated with faster rate of MD decline. Other factors significantly associated with faster progression in multivariate models were older age (coefficient: -0.02, P<0.05) and the presence of systemic hypertension (coefficient: -0.37, P=0.01) and diabetes (coefficient: -0.28, P=0.05). CONCLUSIONS: Lower superficial vessel density measured using OCTA was significantly associated with faster VF progression in PACG. In these eyes, OCTA parameters can serve as biomarker suggestive of past VF progression.

A comparison of the corneal biomechanics in pseudoexfoliation glaucoma, primary open-angle glaucoma and healthy controls using Corvis ST.

PURPOSE: To compare the corneal biomechanical parameters between pseudoexfoliation glaucoma (PXG), primary open-angle glaucoma (POAG) and healthy controls using Corvis ST. METHODS: A prospective, cross-sectional study was conducted which included 132 treatment-naïve eyes which underwent Corvis ST. The study cohort comprised of 44 eyes with PXG, 42 eyes with POAG and 46 healthy controls. Corneal biomechanical parameters, which included corneal velocities, length of corneal applanated surface, deformation amplitude (DA), peak distance and radius of curvature, were compared between the groups using analysis of variance models. RESULTS: The 3 groups were demographically similar. The mean IOP was 15.7 ±3 mmHg in the control group, 21.3 ±5 mmHg in the POAG group and 25.8 ±7 mmHg in the PXG group (p<0.0001). Corneal pachymetry was similar across the 3 groups. Mean DA was significantly lower (p<0.0001) in the PXG group (0.86 ±0.18 mm) compared to the POAG group (0.97 ±0.14mm) and the control group (1.10 ±0.15mm). Corneal velocities were also found to be statistically significantly different between the groups. However, after adjusting for IOP, there was no difference in any of the biomechanical parameters between the 3 groups. CONCLUSION: Corneal biomechanical parameters measured on Corvis ST are not different between eyes with PXG, POAG and healthy controls after adjusting for IOP.

A Comparison of the Visual Field Parameters of SITA Faster and SITA Standard Strategies in Glaucoma.

PURPOSE: To compare the visual field (VF) parameters of the new Swedish Interactive Thresholding Algorithm (SITA), SITA Faster (SFR) with that of SITA Standard (SS) on the Humphrey Field Analyzer. METHODS: Ninety-seven eyes of 97 subjects (63 glaucoma, 26 glaucoma suspects, and 8 normal eyes) underwent VF examination with SFR and SS strategies on the same day in random order. Agreement in VF parameters between SFR and SS strategies was assessed by Bland and Altman plots. In addition, some subjects underwent a second VF examination with SFR strategy to evaluate its test-retest variability. RESULTS: The median test duration of SS strategy was 6 minutes 14 seconds, whereas SFR was 2 minutes 49 seconds (55% shorter, P<0.001). Median mean deviation (-7.3 vs. -7.6 dB, P=0.73) and VF index (88 vs. 88%, P=0.32) were similar between the 2 strategies, whereas pattern standard deviation was significantly higher (4.8 vs. 4.7 dB, P=0.01) with SS strategy. Overall average threshold sensitivity and Garway-Heath sector-wise threshold sensitivities were similar between the 2 strategies except for the nasal sector where SFR strategy had higher sensitivity (26 vs. 25 dB, P=0.02). Bland-Altman plots showed the mean difference in all VF parameters between the SS and SFR strategies were small (ranging from -1.0 dB for the nasal sector to -0.01 dB for superotemporal sector sensitivity). The test-retest variability of VF parameters with SFR strategy was low. CONCLUSIONS: VF parameters with SFR showed good agreement with that of SS strategy. This, combined with low test-retest variability, suggests that SFR can be considered for diagnosis and monitoring of glaucoma.

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.

Choroidal Microvascular Dropout in Primary Open-angle Glaucoma Eyes With Disc Hemorrhage.

PURPOSE: The main purpose of this study was to compare the prevalence of choroidal microvascular dropout (CMvD) in primary open-angle glaucoma (POAG) eyes with and without disc hemorrhage (DH). METHODS: In a cross-sectional study, 44 eyes of 44 control subjects, 32 eyes of 32 POAG patients with DH, and 41 eyes of 41 POAG patients without DH underwent visual fields (VFs), optical coherence tomography (OCT) and OCT angiography (OCTA). Presence of CMvD was evaluated on the choroidal OCTA slab. VF defect in the glaucoma eyes were classified into initial nasal defect, initial parafoveal scotoma, and combined nasal and parafoveal defect. RESULTS: CMvD was detected in 17 POAG eyes with DH (53.1%) and 13 POAG eyes without DH (31.7%; P=0.06). On univariate analysis, CMvD in POAG eyes was associated with DH [odds ratio (OR): 2.44, P=0.06] and measures of glaucoma severity: VF mean deviation (OR: 0.85, P=0.02), retinal nerve fiber layer thickness (OR: 0.95, P=0.03), and peripapillary vessel density (OR: 0.94, P=0.09). On multivariate models that accounted for the measures of glaucoma severity, CMvD in POAG eyes was statistically significantly associated with DH (OR≥3, P<0.05). CMvD was more frequently seen in eyes with initial parafoveal scotoma than initial nasal defect both in POAG eyes with DH (P=0.06) and POAG eyes without DH (P<0.001). CONCLUSIONS: Prevalence of CMvD was significantly greater in POAG eyes with DH compared with POAG eyes without DH. CMvD in POAG eyes was also significantly associated with central VF defects and greater severity of glaucomatous damage.

Choroidal Microvascular Dropout in Primary Angle Closure Glaucoma.

PURPOSE: To determine the prevalence and factors associated with the presence of choroidal microvascular dropout (CMvD) in primary angle-closure glaucoma (PACG) eyes compared to primary open-angle glaucoma (POAG) eyes. DESIGN: Cross-sectional study. METHODS: Thirty-six POAG eyes (36 patients) and 28 PACG eyes (28 patients) underwent optical coherence tomography angiography (OCTA). Presence of CMvD was evaluated on choroidal OCTA slabs. Visual field (VF) defects in the glaucoma eyes were classified into initial nasal defect (IND), initial parafoveal scotoma (IPFS), and combined nasal and parafoveal defect, and the association between type of VF defect and CMvD was evaluated. RESULTS: CMvD was detected in 21 POAG (58.3%) and 10 PACG (35.7%) eyes (P = .07). CMvD in POAG eyes was associated with pretreatment intraocular pressure (odds ratio [OR] = 0.91/mm Hg higher intraocular pressure, P = .06), VF mean deviation (MD, OR = 0.75/dB higher MD, P = .007), retinal nerve fiber layer thickness (OR = 0.92/µm increase in thickness, P = .02), and peripapillary vessel density (OR = 0.80/unit increase in density, P = .01). CMvD in PACG eyes was associated only with VF MD (OR = 0.90/dB higher MD, P = .05). When analyzed in the entire cohort of glaucoma patients (64 eyes), CMvD was significantly associated with POAG (OR > 3.5, P < .05) after accounting for glaucoma severity. CMvD was seen in 6 of 7 eyes with IPFS and 1 of 13 with IND in the POAG group (P < .05) and 1 of 2 eyes with IPFS and 0 of 10 with IND in the PACG group (P < .05). CONCLUSIONS: Prevalence of CMvD was significantly lower in PACG compared to POAG. As in POAG, CMvD in PACG was associated with advanced VF damage and with IPFS on VF.

A Sectoral Analysis of Vessel Density Measurements in Perimetrically Intact Regions of Glaucomatous Eyes: An Optical Coherence Tomography Angiography Study.

PURPOSE: To study sectoral vessel density (VD) and structural alterations in the peripapillary and parafoveal hemiretina corresponding to perimetrically intact regions of glaucomatous eyes with hemifield defects and to compare these with healthy eyes using optical coherence tomography. METHODS: This cross-sectional study included 37 eyes with open-angle glaucoma having visual fields defects restricted to 1 hemifield and 45 age-matched controls. Peripapillary VD and retinal nerve fiber layer (RNFL) thickness were measured in 8 sectors. Parafoveal VD and ganglion cell complex thickness were measured in the superior and inferior hemispheres of the macula. These parameters were compared between the intact hemiretinae of glaucomatous eyes and corresponding sectors of healthy eyes using the t test. RESULTS: Within the perimetrically intact regions of glaucomatous eyes, the mean VD and RNFL thickness were significantly reduced in inferotemporal, superonasal, and nasal upper peripapillary sectors as compared with healthy eyes (P<0.008). The temporal upper sector had reduced mean VD (60.3% vs. 62.9%, P=0.04) despite similar mean RNFL thickness (P=0.18). The superotemporal sector had decreased mean RNFL thickness (121 vs. 138 µm, P=0.0001) despite similar VD (P=0.06). At the macula, ganglion cell complex thickness was reduced in the superior and inferior hemispheres, but mean VD was reduced in the superior parafoveal region only. CONCLUSIONS: Peripapillary and parafoveal vascular changes precede functional decline. The extent of VD reduction and RNFL thinning varies in different peripapillary sectors and longitudinal studies are required to better understand the temporal relationship of vascular and RNFL loss.

Does the Presence of a Disc Hemorrhage Affect OCT-Measured Vessel Density and Retinal Nerve Fiber Layer Thickness?

PURPOSE: To determine if the presence of disc hemorrhage (DH) causes any artifactual change in peripapillary vessel density (VD) and retinal nerve fiber layer (RNFL) thickness as measured by OCT. DESIGN: Cohort study. PARTICIPANTS: Glaucoma patients having a single peripapillary DH. METHODS: Fifteen glaucoma patients having a single peripapillary DH underwent OCT and OCT angiography. Patients were reviewed every 2 months and scans were repeated on disappearance of the DH. Peripapillary VD and RNFL thickness were evaluated at these 2 time points in the DH sector to determine whether the presence of a DH affects these measurements. The mirror-image sector (e.g., superotemporal sector if DH is inferotemporal) was used as a control. Statistical analysis was carried out using the paired t test. Additionally, the analysis of covariance test was used to determine if there was any difference in the measurements between the visits after controlling for signal strength index (SSI). MAIN OUTCOME MEASURES: Peripapillary VD and RNFL thickness were measured in the presence of a DH, and then after DH resolution. RESULTS: The mean ± standard deviation (SD) interval between scans was 4.0±0.4 months. The inferotemporal sector was the most common site of DH (66.6%). The mean ± SD intraocular pressure was reduced medically from 16.1±4.7 mmHg at the time of DH to 13.4±4.2 mmHg at the time of DH resolution (P = 0.001). The mean ± SD VD in the DH sector was 52.5±9.7% at the time of DH and 51.1±8.7% on DH resolution (P = 0.30). The mean ± SD RNFL thickness in the DH quadrant was 91±20 µm in the presence of DH and 92±21 µm after DH resolution (P = 0.26). There was no significant difference between the mean VD or the mean RNFL thickness in the DH and control quadrants at these 2 time points after controlling for change in SSI (P > 0.05). CONCLUSIONS: The presence of a DH does not artifactually alter the VD or RNFL thickness measurements. Therefore, OCT scans obtained in the presence of a DH may be included in series used for studying progression.