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Sara Vaz-Pereira, Gabriella De Salvo, Rebecca Smith, Robin Hamilton; Classification of central retinal vein occlusion using ultra-widefield fluorescein angiography. Invest. Ophthalmol. Vis. Sci. 2014;55(13):252.
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To classify fluorescein angiograms (FA) of central retinal vein occlusion (CRVO) patients by using ultra-widefield scanning laser ophthalmoscope and to correlate these findings with the Central Retinal Vein Occlusion Study (CVOS) grading.
Retrospective, non-interventional, cross-sectional study of patients with CRVO that had ultra-widefield FA (UWFA) performed with the Optos® 200Tx imaging system at Moorfields Eye Hospital. The images obtained were transformed into a “stereographic projection” and a 30° grid with 8 standard fields was superimposed as per the CVOS protocol, using the Optos Dropbox Projection and Grid Tool. Areas of retinal non-perfusion, defined as angiographically visually significant hypofluorescence of an area ≥1 disc diameter or areas of microvascular pathology, were manually measured in mm2 using ImageJ and the Optos Dropbox Area Measurement Tool and converted to disk areas (DA) in mm2 as per the Macular Photocoagulation Study. All images were further classified into ischemic/non-ischemic according to the CVOS angiographic criteria (cut-off 10 DA). Results obtained with UWFA were correlated with the ones that would be obtained by the conventional CVOS FA fields.
UWFA images from 17 eyes of 17 patients with CRVO were analysed (11 male, mean age±standard deviation [SD] 65.2±11.4 years). The mean±SD DA obtained were 101.4±81.8 mm2 with UWFA and 31.0±31.9 mm2 with CVOS FA fields and this difference was statistically significant (p<0.001). By the CVOS FA fields, non-ischemic CRVO was present in 6 (35.3%) eyes and ischemic CRVO in 11 (64.7%) eyes. Using UWFA, non-ischemic and ischemic CRVO were graded, respectively in 2 (11.8%) and 15 (88.2%) eyes. Classification agreement between UWFA and CVOS grading occurred in 13 (76.5%) eyes and there was no statistically significant difference in the final classification between methods (p=0.125).
The UWFA is a new imaging system in which nearly all the retina is captured. It has the potential to better assess the peripheral retina ischemia and to check areas that may be difficult to image with conventional cameras. Although there was no difference in the final classification, there was a significant difference in the DA identified between methods. Therefore, the detection of further ischemia with UWFA may have implications for visual function and provide further insights as to the need of early treatment.
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