Colin S Tan1, Milton C Chew2, Jano van Hemert3, Michael A Singer4, Darren Bell4, SriniVas R Sadda5. 1. National Healthcare Group Eye Institute, Tan Tock Seng Hospital, Singapore, Singapore Fundus Image Reading Center, National Healthcare Group Eye Institute, Singapore, Singapore. 2. National Healthcare Group Eye Institute, Tan Tock Seng Hospital, Singapore, Singapore. 3. Global R&D, Optos Plc, Dunfermline, UK. 4. Department of Ophthalmology, Medical Center Ophthalmology Associates, San Antonio, Texas, USA. 5. Doheny Eye Institute, University of California Los Angeles, Los Angeles, USA.
Abstract
OBJECTIVE: To determine the calculated, anatomically correct, area of retinal non-perfusion and total area of visible retina on ultra-widefield fluorescein angiography (UWF FA) in retinal vein occlusion (RVO) and to compare the corrected measures of non-perfusion with the ischaemic index. METHODS: Uncorrected UWF FA images from 32 patients with RVO were graded manually for capillary non-perfusion, which was calculated as a percentage of the total visible retina (uncorrected ischaemic index). The annotated images were converted using novel stereographic projection software to calculate precise areas of non-perfusion in mm(2), which was compared as a percentage of the total area of visible retina ('corrected non-perfusion percentage') with the ischaemic index. RESULTS: The precise areas of peripheral non-perfusion ranged from 0 mm(2) to 365.4 mm(2) (mean 95.1 mm(2)), while the mean total visible retinal area was 697.0 mm(2). The mean corrected non-perfusion percentage was similar to the uncorrected ischaemic index (13.5% vs 14.8%, p=0.239). The corrected non-perfusion percentage correlated with uncorrected ischaemic index (R=0.978, p<0.001), but the difference in non-perfusion percentage between corrected and uncorrected metrics was as high as 14.8%. CONCLUSIONS: Using stereographic projection software, lesion areas on UWF images can be calculated in anatomically correct physical units (mm(2)). Eyes with RVO show large areas of peripheral retinal non-perfusion. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/
OBJECTIVE: To determine the calculated, anatomically correct, area of retinal non-perfusion and total area of visible retina on ultra-widefield fluorescein angiography (UWF FA) in retinal vein occlusion (RVO) and to compare the corrected measures of non-perfusion with the ischaemic index. METHODS: Uncorrected UWF FA images from 32 patients with RVO were graded manually for capillary non-perfusion, which was calculated as a percentage of the total visible retina (uncorrected ischaemic index). The annotated images were converted using novel stereographic projection software to calculate precise areas of non-perfusion in mm(2), which was compared as a percentage of the total area of visible retina ('corrected non-perfusion percentage') with the ischaemic index. RESULTS: The precise areas of peripheral non-perfusion ranged from 0 mm(2) to 365.4 mm(2) (mean 95.1 mm(2)), while the mean total visible retinal area was 697.0 mm(2). The mean corrected non-perfusion percentage was similar to the uncorrected ischaemic index (13.5% vs 14.8%, p=0.239). The corrected non-perfusion percentage correlated with uncorrected ischaemic index (R=0.978, p<0.001), but the difference in non-perfusion percentage between corrected and uncorrected metrics was as high as 14.8%. CONCLUSIONS: Using stereographic projection software, lesion areas on UWF images can be calculated in anatomically correct physical units (mm(2)). Eyes with RVO show large areas of peripheral retinal non-perfusion. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/
Authors: Eric E Jung; Michelle Lin; Christine Ryu; Stavros N Moysidis; Bruce Burkemper; Rajan Murgai; Amirmohsen Arbabi; Hossein Ameri Journal: J Curr Ophthalmol Date: 2021-03-26