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Localized changes in retinal nerve fiber layer reflectance intensity are related to localized functional loss in glaucoma
Author(s) -
Gardiner S.,
Demirel S.,
Reynaud J.,
Fortune B.
Publication year - 2015
Publication title -
acta ophthalmologica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.534
H-Index - 87
eISSN - 1755-3768
pISSN - 1755-375X
DOI - 10.1111/j.1755-3768.2015.0634
Subject(s) - nerve fiber layer , glaucoma , retinal , ophthalmology , intensity (physics) , optical coherence tomography , medicine , visual field , thinning , optic nerve , optics , physics , biology , ecology
Purpose Reflectance within the retinal nerve fiber layer ( RNFL ) may change prior to, or concurrent with, RNFL thinning in glaucoma. We hypothesize that reductions in RNFL reflectance intensity may be observed by optical coherence tomography ( OCT ), and may provide useful additional information beyond RNFL thickness. Methods Participants enrolled in an ongoing longitudinal study of glaucomatous progression had peripapillary circle scans acquired using spectral‐domain OCT , and performed automated perimetry, every 6 months. Data were analyzed from the most recent 8 visits with reliable results, from 211 eyes of 143 individuals. For each of the 52 visual field locations, intensity ratio and RNFL thickness were calculated within a 30º sector centered at the average location where corresponding nerve fibers enter the disc. Intensity ratio was defined as the mean intensity of pixels within the delineated RNFL boundaries divided by the mean intensity of pixels between the outer RNFL boundary and Bruch's Membrane. Rates of localized change were defined as the rate of change within each sector/location, minus the rate of global change. A mixed effects model was used to predict the rate of localized functional change from the rates of localized thickness and intensity ratio change within the corresponding sector. Results In a combined model, the rate of localized functional loss was predicted by both rate of thinning and the interaction between the rates of thinning and intensity ratio change (both p < 0.0001). For a given rate of RNFL thinning, a more negative rate of intensity ratio change predicted more rapid loss of sensitivity. Conclusions Reduction of RNFL reflectance over time is associated with loss of sensitivity at corresponding locations. While these are early results, they suggest potential improvements to the interpretation and quantification of OCT scans.