The Relationship Between Retinal Vessel Oxygenation and Spatial Distribution of Retinal Nonperfusion in Retinal Vascular Diseases

Purpose: We study the relationship between retinal vessel oxygenation and the spatial distribution of retinal nonperfusion using ultrawide field angiography in eyes with retinal vascular diseases. Methods: This prospective single center study recruited 57 eligible eyes from 44 patients with retinal vascular diseases. Retinal oximetry measurements were obtained using the Oxymap T1 device to determine the arteriovenous (AV) difference. Retinal nonperfusion was measured from ultrawide field angiography images taken with the Optos 200TX system and superimposing the images with the concentric rings template to determine the area and distribution of retinal nonperfusion. Results: Seven (12.3%) eyes had a diagnosis of a branch or hemiretinal vein occlusion, 24 (42.1%) with central retinal vein occlusion and 26 (45.6%) with diabetic retinopathy (11 [19.3%] nonproliferative and 15 [26.3%] proliferative diabetic retinopathy). The correlation between the total area of retinal nonperfusion with the AV difference controlling for age was not statistically significant (R = -0.103, P = 0.449). However, when analyzing the correlation of AV difference with the area of retinal nonperfusion in the posterior pole controlling for age and peripheral nonperfusion, this was significant (R = -0.295, P = 0.029). This was not significant for the area of retinal nonperfusion in the periphery while controlling for posterior pole nonperfusion and age (R = 0.124, P = 0.368). Conclusions: Retinal nonperfusion has a negative correlation with AV difference measured on retinal oximetry. This correlation is significant in the posterior pole, but not in the peripheral retina

Validation of Concentric Rings Method as a Topographic Measure of Retinal Nonperfusion in Ultra-Widefield Fluorescein Angiography

PURPOSE: To validate the use of concentric rings as a method to measure topographic area of retinal nonperfusion in ultra-widefield angiography with the ischemic index method, which is the most frequently used method to measure nonperfusion in ultra-widefield angiography. DESIGN: Validation study and reliability analysis. METHODS: setting: Single-center study performed at National Institute for Health Research Moorfields Biomedical Research Centre, London, United Kingdom. STUDY POPULATION: Twenty-eight ultra-widefield angiogram images of eyes with central retinal vein occlusion. OBSERVATION PROCEDURE: The concentric rings method consists of 6 macula-centered concentric rings divided into 12 segments each. Each image was graded by 5 graders using both the concentric rings and the ischemic index methods. MAIN OUTCOME MEASURES: Agreement between the 2 methods was calculated using the intraclass correlation coefficient. Intertest agreement, intergrader agreement, test-retest reliability, and the time taken to grade using these 2 methods were compared. RESULTS: The intertest agreement between concentric rings method and ischemic index method was 0.965. The intergrader agreement was 0.910 for the concentric rings method and 0.898 with the ischemic index method. The test-retest reliability was 0.975 for the rings and 0.979 for the ischemic index. Average grading time per image was 187 s and 297 s for the concentric rings method and ischemic index method, respectively, P < .001. CONCLUSION: The concentric rings method has an "almost-perfect" intergrader agreement and intertest agreement with the ischemic index method, with a shorter grading time

Quantifying Retinal Area in Ultra-Widefield Imaging Using a 3-Dimensional Printed Eye Model

Purpose: To study the effects of different axial lengths on ultra-widefield imaging to determine the presence of distortion in images despite software correction and calculate an enlargement factor based on angular location. / Design: Experimental image analysis study. / Study Objects: Three 3-dimensional printed model eyes simulating eyes with axial lengths of 22, 24, and 26 mm. Each model has a grid of rings 9° apart centered at the posterior pole. / Methods: Single-center study performed at the National Institute for Health Research Moorfields Biomedical Research Centre (London, UK). Each model was imaged using Optos 200TX (Optos, Dunfermline, UK). Two images for each model eye that were corrected using V2 Vantage Pro software (Optos) were used for analysis and the average values obtained. Each image inter-ring area was measured using ImageJ to obtain a measured image area in pixel and square millimeters. This was compared with the true calculated object inter-ring area and an enlargement factor was determined. / Main Outcome Measures: Measured image inter-ring area in pixels and square millimeters. True calculated object inter-ring area in square millimeters. / Results: The enlargement factor of the rings gradually increases toward the periphery with factors of 1.4 at 45° and 1.9 at the equator. The axial lengths did not affect the enlargement factor of the rings imaged in 3 different model eyes (P = 0.9512). The anterior equator exhibits a significant distortion despite the software correction. / Conclusion: The enlargement factor depends on angular location and not axial length. The enlargement factors can be used in clinical practice to more accurately measure area in ultra-widefield imaging

Retinal non-perfusion in the posterior pole is associated with increased risk of neovascularization in central retinal vein occlusion.

PURPOSE: To review the definition of ischaemic central retinal vein occlusion (CRVO) and stratify the risk of neovascular complication based on wider areas of visible retinal non-perfusion. DESIGN: Retrospective consecutive case series and image analysis study METHODS: Setting: Moorfields Eye Hospital, London, United Kingdom. STUDY POPULATION: 42 consecutive treatment naïve eyes with CRVO imaged with ultra-widefield angiography with a minimum of 12 months follow-up. OBSERVATION PROCEDURE: The spatial location and total area of retinal non-perfusion (measured in disc areas, DA) were determined using the validated concentric rings method. The area was corrected for projection distortion. The images were graded by two retinal physicians and average measurements used. MAIN OUTCOME MEASURES: Development of neovascular complications. RESULTS: The percentage of eyes developing new vessels increased from none in eyes with less than 10 DA of non-perfusion in total, to 14.3% in eyes with 10-30DA, 20.0% for 30-75DA and 80% risk with 75-150DA of non-perfusion. From 13 (31.0%) eyes with a perfused posterior pole (an area encompassing a five disc diameter radius centered at the fovea) and more than 10DA of non-perfusion isolated in the periphery (beyond the posterior pole), only one (7.7%) eye developed new vessels, OR 0.12 [95% CI:0.01,1.03]. Comparatively, for 13 (31.0%) eyes with more than 10DA of non-perfusion in the posterior pole, 11 (84.6%) developed new vessels, OR 74.25 [95% CI: 9.26, 595.30], p<0.001. CONCLUSION: With ultra-widefield angiography, we have ascertained that posterior pole non-perfusion of more than 10DA remains the key risk factor for new vessel development compared to areas of non-perfusion confined to the periphery

Swept-Source OCT and Near-Infrared Reflectance Patterns in Choroidal Nevi

PURPOSE: To describe the 3 distinct patterns of choroidal nevi in swept-source (SS) OCT and apply that classification to a cohort of consecutive choroidal nevi. Also, we aim to describe the findings of these lesions in near-infrared reflectance (NIR) at different wavelengths (820 and 1050 nm). DESIGN: Single-center, retrospective, observational study. PARTICIPANTS: One hundred four consecutive patients with choroidal nevi. METHODS: Retrospective analysis of choroidal nevi imaged with SS OCT and NIR. MAIN OUTCOME MEASURES: Lesions were classified according to OCT patterns as type A (high reflectivity with optical shadowing), type B (medium reflectivity with partial visualization of the scleral boundary), and type C (hyporeflective with complete visualization of the scleral boundary). RESULTS: Of 104 choroidal nevi, 97 lesions (93.3%) could be classified into 1 of the SS OCT patterns. Forty-nine percent corresponded to type A, 26% corresponded to type C, and 18.3% corresponded to type B. In NIR (n = 820), 76% of lesions were hyperreflective, whereas in NIR (n = 1050), most of the lesions were hyporeflective (59.6%; inverse reflectance). CONCLUSIONS: Choroidal nevi present distinct patterns according to SS OCT features. Clinical implications are yet to be determined. In NIR, inverse reflectance may be a consequence of the confocality of the device, rather than a property of the lesions