Retinal Pigment Epithelial Adenoma: Initial Treatment Outcomes following Episcleral Brachytherapy.

Introduction: We aim to explore the safety and efficacy of episcleral brachytherapy as a primary management option for eyes with retinal pigment epithelial (RPE) adenoma. Methods: Retrospective chart review of the demographic, clinical, ancillary, and postoperative outcome data of patients with RPE adenoma in 2 tertiary referral centers. Tumor regression, final visual acuity, and complications were assessed. Results: Five patients (3 females and 2 males) were included. Four of the 5 eyes had peripheral and mid-peripheral lesions, while one tumor was juxtapapillary. Three eyes were treated with ruthenium-106 (100 Gray), and 2 received iodine-125 episcleral plaques (85 Gray). All eyes showed clinical and imaging-based evidence of regression. Four eyes had stable or improved visual acuity, while 1 eye exhibited one line loss of visual acuity due to radiation retinopathy. Local recurrence was not observed in any eye over a median follow-up of 24 (range 6-112) months. Conclusions: Episcleral brachytherapy is an effective management option for select cases of RPE adenoma that is capable of achieving tumor regression while maintaining favorable visual acuity. The initial safety profile of brachytherapy is good without significant vision-compromising complications.

Retinal vasculature of different diameters and plexuses exhibit distinct vulnerability in varying severity of diabetic retinopathy.

OBJECTIVES: To study the changes in vessel densities (VD) stratified by vessel diameter in the retinal superficial and deep vascular complexes (SVC/DVC) using optical coherence tomography angiography (OCTA) images obtained from people with diabetes and age-matched healthy controls. METHODS: We quantified the VD based on vessel diameter categorized as <10, 10-20 and >20 µm in the SVC/DVC obtained on 3 × 3 mm2 OCTA scans using a deep learning-based segmentation and vascular graph extraction tool in people with diabetes and age-matched healthy controls. RESULTS: OCTA images obtained from 854 eyes of 854 subjects were divided into 5 groups: healthy controls (n = 555); people with diabetes with no diabetic retinopathy (DR, n = 90), mild and moderate non-proliferative DR (NPDR) (n = 96), severe NPDR (n = 42) and proliferative DR (PDR) (n = 71). Both SVC and DVC showed significant decrease in VD with increasing DR severity (p < 0.001). The largest difference was observed in the <10 µm vessels of the SVC between healthy controls and no DR (13.9% lower in no DR, p < 0.001). Progressive decrease in <10 µm vessels of the SVC and DVC was seen with increasing DR severity (p < 0.001). However, 10-20 µm vessels only showed decline in the DVC, but not the SVC (p < 0.001) and there was no change observed in the >20 µm vessels in either plexus. CONCLUSIONS: Our findings suggest that OCTA is able to demonstrate a distinct vulnerability of the smallest retinal vessels in both plexuses that worsens with increasing severity of DR.

Synthetic Optical Coherence Tomography Angiographs for Detailed Retinal Vessel Segmentation Without Human Annotations.

Optical coherence tomography angiography (OCTA) is a non-invasive imaging modality that can acquire high-resolution volumes of the retinal vasculature and aid the diagnosis of ocular, neurological and cardiac diseases. Segmenting the visible blood vessels is a common first step when extracting quantitative biomarkers from these images. Classical segmentation algorithms based on thresholding are strongly affected by image artifacts and limited signal-to-noise ratio. The use of modern, deep learning-based segmentation methods has been inhibited by a lack of large datasets with detailed annotations of the blood vessels. To address this issue, recent work has employed transfer learning, where a segmentation network is trained on synthetic OCTA images and is then applied to real data. However, the previously proposed simulations fail to faithfully model the retinal vasculature and do not provide effective domain adaptation. Because of this, current methods are unable to fully segment the retinal vasculature, in particular the smallest capillaries. In this work, we present a lightweight simulation of the retinal vascular network based on space colonization for faster and more realistic OCTA synthesis. We then introduce three contrast adaptation pipelines to decrease the domain gap between real and artificial images. We demonstrate the superior segmentation performance of our approach in extensive quantitative and qualitative experiments on three public datasets that compare our method to traditional computer vision algorithms and supervised training using human annotations. Finally, we make our entire pipeline publicly available, including the source code, pretrained models, and a large dataset of synthetic OCTA images.

COVID-19 VACCINE-INDUCED ACUTE EXUDATIVE POLYMORPHOUS VITELLIFORM MACULOPATHY: CASE REPORTS.

BACKGROUND: Acute exudative polymorphous vitelliform maculopathy is a presumed retinal pigment epithelium abnormality that has been reported in patients with neoplasms and under certain classes of drugs. The pathophysiology remains unclear, despite the typical clinical features. PURPOSE: To report two cases of acute exudative polymorphous vitelliform maculopathy occurring after vaccination with a COVID-19 vaccine. CASE REPORTS: Two adult patients presented with visual disturbance after inoculation with a COVID-19 vaccine. The patients were otherwise healthy and have no family history of retinal dystrophies. Both cases exhibited the following features on multimodal imaging: multifocal hyporeflective lesions involving the macula, elongated photoreceptors, accumulated vitelliform material exhibiting autofluorescence, and lack of fluorescein dye leakage. Evidence of retinal pigment epithelium dysfunction was confirmed by electrooculography. CONCLUSION: Two cases of acute exudative polymorphous vitelliform maculopathy occurring after COVID-19 vaccination were reported. A relationship between the vaccine and the retinal pigment epithelial abnormality development that led to acute exudative polymorphous vitelliform maculopathy was postulate, possibly through autoantibodies against the severe acute respiratory syndrome coronavirus 2 virus structural surface glycoprotein antigens that cross react with the normal retinal pigment epithelial cells.

Diminished choroidal blood flow in hypertensive and preeclamptic third trimester pregnancies using optical coherence tomography angiography.

PURPOSE: The aim of this study was to compare choroidal adjusted flow index (AFI) in healthy, hypertensive & preeclamptic pregnancies using optical coherence tomography angiography (OCTA). METHODS: In this prospective study, healthy, hypertensive & preeclamptic third trimester pregnant women underwent OCTA imaging. 3x3 & 6x6 mm choriocapillaris slabs were exported and the parafoveal area was marked by two concentric ETDRS circles at 1 & 3 mm, centered on the foveal avascular zone. Parafoveal AFI was calculated as a parameter of choroidal blood flow. RESULTS: Fifteen eyes of fifteen women per group were recruited (45 eyes). AFI was significantly lower in the preeclamptic compared to the healthy & hypertensive groups (Tukey HSD: <0.001 in both groups on 3x3 mm, and 0.02 & 0.04 in 6x6 mm scans), and in the hypertensive compared to the healthy group (0.005 & 0.03 in 3x3 & 6x6 mm scans respectively). CONCLUSIONS: Pregnancies complicated with preeclampsia revealed the lowest choroidal blood flow on OCTA followed by pregnancies with systemic hypertension compared to healthy pregnancies. We provide in-vivo documentation of choroidal ischemia, highlighting its culpability in hypertensive and preeclamptic retinochoroidal pathology, and the possibility of utilizing choroidal blood flow on OCTA as a precursor for disease progression.

Case Report: Acquired Brown Syndrome after COVID-19 Vaccination.

SIGNIFICANCE: Brown syndrome, or superior oblique tendon sheath syndrome, is characterized by limitation of elevation on adduction. The disorder is thought to involve the trochlea/superior oblique tendon complex through traumatic, surgical, and inflammatory mechanisms. It could be an indication of multiple underlying immunological or rheumatological disorders. PURPOSE: This study aimed to report an unusual strabismus after receiving the first dose of a live attenuated coronavirus disease 2019 (COVID-19) vaccine. CASE REPORT: A 31-year-old female patient presented with painful vertical diplopia and tenderness of the left trochlear area 3 days after the first dose of COVID-19 vaccination. She had a compensatory chin elevation and face turn to the right, as well as a left 10-prism-diopter hypotropia in the primary position, which increased to 15 prism diopters in the right gaze and disappeared in the left gaze. Ocular motility revealed the limitation of elevation on adduction. The patient denied any history of ocular trauma and was consequently investigated for dysthyroid disease and various immunological and rheumatological disorders, which were excluded. A Hess chart was obtained to document the motility disorder. CONCLUSIONS: We report a case of acquired Brown syndrome in a 31-year-old otherwise healthy woman shortly after COVID-19 vaccination. It is possible that the patient may have developed trochleitis and/or superior oblique tenosynovitis brought on by cross-reacting antibodies generated by the immune response to the vaccine. In the age of the widest vaccination campaign in human history, it is highly likely that we will continue to observe many unexpected potential adverse effects of these vaccines in our clinical practice.

OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY REVEALS PARADOXICALLY DECREASING CHOROIDAL THICKNESS AND INCREASING BLOOD FLOW IN REMITTING VOGT-KOYANAGI-HARADA SYNDROME.

PURPOSE: To assess changes in choroidal thickness and blood flow in active Vogt-Koyanagi-Harada syndrome and after remission using optical coherence tomography angiography. METHODS: This was a prospective study of patients with active early uveitis secondary to Vogt-Koyanagi-Harada syndrome. They underwent optical coherence tomography angiography imaging twice: at baseline and after remission on treatment. 3- × 3- and 6- × 6-mm choriocapillaris slabs were used to evaluate parafoveal adjusted flow index as a marker for choroidal blood flow. Mean choroidal thickness of 3 points (subfoveally and 2 points 300 µ m parafoveally) was also measured. RESULTS: Thirty-nine eyes of 25 patients were initially recruited. After excluding eyes with media opacity, submacular fibrosis, and choroidal neovascularization, 23 eyes of 14 patients were included. The mean follow-up period was 8.7 ± 2.5 months. Mean choroidal thickness in activity and remission was 581.65 ± 108.29 µ m and 318.34 ± 72.85 µ m respectively ( P < 0.01). Mean adjusted flow index in the 3- × 3-mm slabs activity and remission were 0.495 ± 0.027 and 0.519 ± 0.0336 ( P = 0.011), and the 6- × 6-mm slabs were 0.487 ± 0.037 and 0.517 ± 0.052 respectively ( P = 0.025). CONCLUSION: We demonstrate decreasing choroidal thickness with paradoxically increasing choroidal flow on optical coherence tomography angiography in remitting Vogt-Koyanagi-Harada syndrome. This may reflect inflammatory infiltrations or granulomas increasing choroidal thickness during activity and causing sluggish circulation of the choriocapillaris, and a reversal of this process with remission. These findings shed more light on the relationship between Vogt Koyanagi Harada syndrome and its underlying choroidal disturbances. Larger studies are needed to evaluate the efficacy of adjusted flow index in evaluating and predicting disease activity.

Masking of macular neovascular membranes by subretinal hyperreflective material on optical coherence tomography angiography.

PURPOSE: The purpose of this study was to determine whether subretinal hyperreflective material (SHRM) may mask the detection of macular neovascular membranes (MNV) on optical coherence tomography angiography (OCTA). METHODS: In this observational study, eyes with active neovascular age-related macular degeneration (nAMD), co-existing SHRM & intraretinal or subretinal fluid or hemorrhage on structural OCT, underwent OCTA & fundus fluorescein angiography (FFA) imaging. 6 × 6 mm choriocapillaris and outer retinal slabs on OCTA were examined to determine the presence of MNV underneath the SHRM. The corresponding area on FFA was used as a reference arm to confirm activity. RESULTS: Thirty eyes of thirty patients with SHRM and active nAMD were recruited. All eyes failed to show a MNV in the choriocapillaris & avascular slabs of the OCTA underneath the SHRM, but showed active hyperfluorescent MNVs that increased in size and intensity in the late stages of FFA. In one eye, parts of a MNV under the SHRM were undetectable due to signal attenuation, while parts extending beyond the SHRM were detected on the choriocapillaris en face slab with flow on the B scan. CONCLUSIONS: SHRM may act as a reflecting surface that limits the passage of light waves in OCTA, creating areas of signal attenuation and diminishing its ability to detect underlying MNVs.

Unique presentations of aspergillosis endogenous endophthalmitis in two hospitalized patients with severe COVID-19.

We present two ICU-hospitalized patients with coronavirus disease-19 (COVID-19) presenting with endogenous endophthalmitis in one eye and variable manifestations of chorioretinitis in the fellow eye. Two diabetic patients (57 and 62 years old) showed anterior uveitis and yellowish-white subretinal infiltrations. The fellow eye of one patient showed patches of choroiditis, while the other showed full retinal thickness infiltrations. A workup yielded high serum titers of galactomannan, diagnostic of aspergillosis. The widespread use of high doses of corticosteroids in the management of COVID-19 may predispose to various secondary fungal opportunistic infections and may manifest in different forms of chorioretinal infiltration.

Choriocapillaris Island: an optical coherence tomography angiography finding observed in central serous chorioretinopathy.

PURPOSE: To report the observation of the choriocapillaris island (CCI) on optical coherence tomography angiography (OCTA) in eyes with active central serous chorioretinopathy (CSCR), and to investigate its associated clinical features. DESIGN: Retrospective observational study. METHODS: Patients diagnosed with active CSCR underwent OCTA imaging (Optovue Inc, Fremont, California, USA), and the software built-in en face choriocapillaris slab was examined to demonstrate CCI, defined as an area of detectable choriocapillaris flow surrounded by an area of undetectable or diminished flow. Electronic medical records (EMR) were reviewed for demographics, clinical data, other imaging modalities and any intervention, and these parameters were correlated with CCI findings. RESULTS: 25 eyes of 25 patients were recruited. CCI was detected in all examined eyes and was best elucidated on the en face choriocapillaris density maps. 24 eyes had focal retinal pigment epithelium (RPE) alterations overlying CCI. All 14 eyes with simultaneous fundus fluorescein angiography (FA) showed actively leaking point(s) well corresponding to the CCI location. Resolution of sub-retinal fluid in 4 eyes was associated with disappearance of CCI on follow-up OCTA scans. 1 eye showed complicating neovascularization 5 months after the initial presentation at the same location of the CCI. CONCLUSION: We demonstrate the observation of the "choriocapillaris island" an OCTA finding in eyes with active CSCR underneath the area of neurosensory detachment. CCI may constitute an angiographic representation of the focal area of choriocapillaris structural and functional affection, with secondary RPE alteration jeopardizing its barrier function. Larger longitudinal studies are needed to further elucidate this finding.

Optical coherence tomography angiography reveals progressive worsening of retinal vascular geometry in diabetic retinopathy and improved geometry after panretinal photocoagulation.

PURPOSE: To quantify vessel tortuosity and fractal dimension of the superficial capillary plexus (SCP) of the macula in different stages of diabetic retinopathy (DR), and following panretinal photocoagulation (PRP) using optical coherence tomography angiography (OCTA). METHODS: 75 eyes of 75 subjects were divided into five groups; healthy controls, diabetes with no clinical DR, non-proliferative diabetic retinopathy (NPDR), proliferative diabetic retinopathy (PDR) and patients who received PRP for PDR (PDR+PRP).For vessel tortuosity, SCP slabs from 3x3 mm macular OCTA scans were processed using imageJ (NIH, USA), where large perifoveal vessels were traced and their length was measured with tortuosity calculated as the ratio between the actual length and the straight Euclidean length. For fractal dimension, SCP slabs were processed and imported to Fractalyse (ThéMA, France), where box-counting analyses produced fractal dimension values. RESULTS: We found a significant difference in vessel tortuosity and fractal dimension between the five groups (one-way ANOVA, p < 0.001both). NPDR and PDR had significantly more tortuous vessels and lower fractal dimension compared to healthy controls (Tukey HSD: p = 0.02, 0.015,0.015 and <0.001, respectively). Fractal dimension was also significantly lower in NPDR and PDR compared to eyes with no clinical DR (p <0.001 both), and in PDR compared to NPDR (p = 0.014). Following PRP, vessel tortuosity was significantly lower and fractal dimension was higher in PDR+PRP compared to PDR (p = 0.001 and 0.031, respectively). CONCLUSIONS: We used macular OCTA scans to demonstrate significantly higher perifoveal large vessel tortuosity, and lower fractal dimension in NPDR and PDR compared to healthy controls. Vessel tortuosity shows more dramatic normalization than fractal dimension and could be explored as a sensitive marker for successful PRP.

Exploring the relationship between collaterals and vessel density in retinal vein occlusions using optical coherence tomography angiography.

PURPOSE: To characterize the types of collaterals in eyes with retinal vein occlusion (RVO) and further investigate their correlations with vessel densities of the superficial (SCP) and the deep capillary plexus (DCP) using optical coherence tomography angiography (OCTA). METHODS: This cross-sectional study included 25 eyes of 23 patients with RVO. 3 x 3 mm2 OCTA macular scans were used to quantify the parafoveal vessel density (VD) of the SCP and DCP, and to classify the collaterals into one of four types (true superficial, true deep, superficial diving, and foveal collateral). Generalized estimating equation (GEE) regression analysis was performed to identify significant associations between parafoveal VD and collaterals. We further compared parafoveal VD between subgroups classified by the presence of specific collateral types based on the results of a clustering algorithm. RESULTS: 16 of 25 eyes (64%) developed collaterals. Of the 43 collateral vessels analyzed, 12/19 (63%) true superficial collaterals developed in eyes with central RVO, while all 10 superficial diving collaterals (100%) developed in eyes with branch RVO. Located exclusively in the SCP, true superficial collaterals were all arteriovenous (A-V), while diving collaterals were all veno-venular (V-V). We found a significant negative correlation between SCP VD and the total number of collaterals (P < 0.001) for the entire study cohort. Furthermore, BRVO eyes that developed superficial diving collaterals and CRVO eyes that developed true superficial collaterals demonstrated significantly lower SCP VD (P-value = 0.014) and DCP VD (P-value = 0.030), respectively, as compared to the eyes without collaterals in the respective RVO group. CONCLUSION: Our data shows that decreased capillary perfusion in RVO is associated with the development of collaterals, while the RVO type largely dictates the type of collateral that ultimately develops.

Projection resolved optical coherence tomography angiography to distinguish flow signal in retinal angiomatous proliferation from flow artifact.

PURPOSE: To investigate whether hyperreflective foci (HRF) exhibit flow projection artifact on OCTA, and study the efficacy of commercial projection artifact removal software (PAR-OCTA, Optovue, Inc), and a custom projection resolved OCTA (PR-OCTA) in distinguishing artifacts from true flow in retinal angiomatous proliferation (RAP). METHODS: The study included five eyes with HRF representing pigment migration in dry age-related macular degeneration (AMD), five eyes with leaking treatment-naïve RAP, and ten eyes with diabetic hard exudates. We examined flow signal on OCTA cross-sections using PAR, and performed PR-OCTA to study the effect of increasingly stringent projection removal thresholds. Flow signal intensity was analyzed and quantified using imageJ (NIH, Bethesda, MD, USA), by calculating the percentage of red pixels (R) representing flow, compared to green (G) and blue (B) pixels. RESULTS: PAR-OCTA cross sections revealed persistent flow signal in all HRF, including RAP, hard exudates and pigment migration. In RAP, PR-OCTA detected intransigent flow, irrespective of the flow removal threshold. Mean R in the five RAP lesions remained higher than mean G and B at the most stringent PR-OCTA threshold (40.96% vs 29.52 and 29.52%, respectively), denoting persistence of flow. In contrast, increasing the PR-OCTA threshold in pigment migration and hard exudates removed the flow signal, with a statistically significant decrease in mean R with increasing threshold. (p = 0.017 and 0.0029, respectively). CONCLUSION: Commercial PAR-OCTA is not completely effective at removing artifactual flow in hard exudates and HRF related to pigment migration. Custom built PR-OCTA, using a sliding scale of threshold, allowed us to distinguish true flow in RAP from artifactual flow in avascular HRF. Further studies are needed to validate the optimum threshold for projection artifact removal, which would preserve true flow in RAP and the small intraretinal capillaries.

Improved Macular Capillary Flow on Optical Coherence Tomography Angiography After Panretinal Photocoagulation for Proliferative Diabetic Retinopathy.

PURPOSE: This study evaluated the macular microvascular changes in eyes with proliferative diabetic retinopathy (PDR) following panretinal photocoagulation (PRP). DESIGN: Using optical coherence tomographic angiography (OCTA), we prospectively studied 10 eyes of 10 subjects with high-risk PDR immediately before, at 1 month, and at 3-6 months following PRP, using a 3- × 3-mm OCTA scan at each visit. METHODS: The following parameters were calculated for the superficial (SCP), middle (MCP), and deep capillary plexuses (DCP): parafoveal vessel density (VD), adjusted flow index (AFI), and percent area of nonperfusion (PAN). Parafoveal SCP vessel-length density (VLD) was also evaluated. We performed univariate and multivariable statistics, adjusting for age and signal strength. To model the hemodynamic effect of PRP, we also present a mathematical model based on electrical circuits. RESULTS: We found no significant difference for the vascular density parameters following PRP, except for decreased density at the MCP at the latest timepoint in the adjusted multivariable model. PAN, a metric of nonperfusion adjusted for noise, and AFI, a surrogate metric of blood flow, showed significant increases at all capillary levels in the adjusted model. Our mathematical model explained how PRP would increase macular blood flow. CONCLUSIONS: Using OCTA, we found an overall increase in the flow metrics of all capillary layers in the macula following PRP, unrelated to macular edema or thickening, in line with the mathematical model. Our results suggest an overall redistribution of blood flow to the posterior pole following PRP, adding a new dimension to our understanding of the complex biologic effects of PRP in PDR. NOTE: Publication of this article is sponsored by the American Ophthalmological Society.

Hemodynamic Response of the Three Macular Capillary Plexuses in Dark Adaptation and Flicker Stimulation Using Optical Coherence Tomography Angiography.

Purpose: To assess retinal microvascular reactivity during dark adaptation and the transition to ambient light and after flicker stimulation using optical coherence tomography angiography (OCTA). Methods: Fifteen eyes of 15 healthy participants were dark adapted for 45 minutes followed by OCTA imaging in the dark-adapted state. After 5 minutes of normal lighting, subjects underwent OCTA imaging. Participants were then subjected to a flashing light-emitting diode (LED) light and repeat OCTA. Parafoveal vessel density and adjusted flow index (AFI) were calculated for superficial (SCP), middle (MCP), and deep capillary plexuses (DCP), and then compared between conditions after adjusting for age, refractive error, and scan quality. SCP vessel length density (VLD) was also evaluated. Between-condition capillary images were aligned and subtracted to identify differences. We then analyzed images from 10 healthy subjects during the transition from dark adaptation to ambient light. Results: SCP vessel density was significantly higher while SCP VLD was significantly lower during ambient light and flicker compared to dark adaptation. There was a significant positive mean value for DCP "flicker minus dark or light," suggesting more visible vessels during flicker due to changes in flow, dilation, or vessel recruitment. We found a significant, transient increase in SCP and decrease in both MCP and DCP vessel density during the transition from dark to light. Conclusions: We show evidence suggesting constriction of deeper vessels and dilation of large SCP vessels during the transition from dark to light. This contrasts to redistribution of blood flow to deeper layers during dark adaptation and flicker stimulation.

Agreement profiles for rebound and applanation tonometry in normal and glaucomatous children.

OBJECTIVES: To investigate agreement between intraocular pressure measurements by the rebound tonometer and handheld Perkins applanation tonometer in children with and without primary congenital glaucoma and test agreement with intraocular pressure and age variations. MATERIALS AND METHODS: A prospective non-interventional comparative study done on 223 eyes of 115 children, 161 normal eyes, and 62 eyes with primary congenital glaucoma. Intraocular pressure measurements were obtained in the upright position by rebound tonometer first, followed by installation of topical anesthetic eye drops (benoxinate), then measured by Perkins applanation tonometer. RESULTS: For all eyes, mean difference between Perkins applanation tonometer and rebound tonometer was -0.59 ± 2.59 mmHg, p = 0.001. Regression analysis with (r) = 0.9, (r2) = 0.79, and p < 0.001. In primary congenital glaucoma: there was a mean difference of -.79 ± 2.82 (p = 0.032), a good correlation with (r) = 0.94, (r2) = 0.87%, and 95% level of agreement: -6.34 to +4.76. In normal eyes: mean difference was -.52 ± 2.5 (p = 0.01), correlation: (r) = 0.8, (r2) = 0.64, and p = 0.001. The 95% level of agreement -5.41 and +4.36 mmHg. In intraocular pressure ⩽ 15 mmHg: mean difference -0.89 ± 2.15 mmHg, 95% level of agreement between -5.1 and +3.32 mmHg, p < 0.001. In intraocular pressure >15 mmHg: mean difference was 0.04 ± 3.28 mmHg, 95% level of agreement -6.38 and +6.46 mmHg, p = 0.914. CONCLUSION: There is a good correlation between rebound tonometer and Perkins applanation tonometer in children with and without primary congenital glaucoma; however, rebound tonometer overestimates the intraocular pressure, and in intraocular pressure >15 mmHg there is less agreement between the two devices. Hence, in higher intraocular pressure measurement caution should be taken when interpreting rebound tonometer readings, and a confirmatory measurement using Perkins applanation tonometer is advised.

Prevalence of Subclinical CNV and Choriocapillaris Nonperfusion in Fellow Eyes of Unilateral Exudative AMD on OCT Angiography.

PURPOSE: To determine the prevalence of subclinical choroidal neovascularization (CNV) in fellow eyes of patients with unilateral exudative age-related macular degeneration (AMD) using optical coherence tomography angiography (OCTA) and to quantify choriocapillaris nonperfusion adjacent to CNV. METHODS: We retrospectively reviewed all patients with AMD who underwent OCTA and identified eyes with unilateral exudative AMD. We determined the presence of subclinical CNV on custom en face macular slabs of the outer retina and choriocapillaris and confirmed on cross-sectional scans. Two graders quantified the percent choriocapillaris area of nonperfusion (PCAN) in the entire choriocapillaris slab as well as in the "halo" zone (200 µm) surrounding subclinical and exudative CNV lesions. RESULTS: Of 140 AMD patients who underwent OCTA, 34 had unilateral exudative AMD, with five of the 34 fellow eyes (14.7%) having subclinical CNV. Compared with PCAN in the entire slab (10.333 ± 4.288%), we found that "halo" PCAN, surrounding CNV, was significantly higher (13.045 ± 5.809%; P < 0.001). Further, there was a trend for higher PCAN in exudative CNV eyes (15.267 ± 7.230%) compared with their fellow subclinical CNV eyes (10.823 ± 3.365%, P = 0.115). CONCLUSIONS: There is a notable prevalence of subclinical CNV in fellow eyes with unilateral exudative CNV, and significantly greater choriocapillaris nonperfusion adjacent to all CNV lesions. We identified a trend for increased choriocapillaris nonperfusion in exudative AMD eyes as compared with their fellow subclinical CNV eyes, which deserves further study. TRANSLATIONAL RELEVANCE: OCTA can be useful in clinical practice to detect subclinical CNV and study choriocapillaris dysfunction.