Relationship between optical coherence tomography retinal parameters and visual acuity in neovascular age-related macular degeneration

Abstract

Purpose: To investigate the relationship between optical coherence tomography (OCT)-derived measurements of retinal morphology and visual acuity in patients with neovascular age-related macular degeneration (AMD).

Design: Retrospective cross-sectional study.

Participants: A total of 216 consecutive patients (216 eyes) newly diagnosed with neovascular AMD who underwent StratusOCT imaging at the time of diagnosis.

Methods: Best-corrected Snellen visual acuity was recorded for each patient. Raw exported StratusOCT images for each patient were analyzed using publicly available custom software entitled "OCTOR," which allows the precise positioning of prespecified boundaries on individual B-scans. Thickness and volume were calculated for morphologic parameters of interest: neurosensory retina, subretinal fluid, subretinal tissue (SRT), and pigment epithelial detachment.

Main outcome measures: OCT-derived measurements of retinal morphology and visual acuity.

Results: An increased total volume of SRT was correlated with decreased visual acuity (r = 0.370, P<0.0001). Decreased visual acuity was also modestly correlated with increased thickness of the neurosensory retina at the foveal center point (r = 0.245, P = 0.0004). No statistically significant association was detected between visual acuity and the total volume of subretinal fluid or pigment epithelial detachment. The association between visual acuity and both the neurosensory retina and the SRT was stronger for lesions classified as minimally classic or occult on fluorescein angiography. For occult lesions, 20% of the variation in visual acuity could be predicted by a multiple regression model that incorporated age and SRT volume, whereas, for minimally classic lesions, 62% of the variation in visual acuity could be predicted by a multiple regression model that incorporated age, total neurosensory retinal volume, and total SRT volume.

Conclusions: The presence of increased SRT thickness and volume on OCT, and to a lesser extent increased neurosensory retinal thickness and volume, is associated with decreased visual acuity in neovascular AMD. However, because of the complex pathophysiology of neovascular AMD and, in part, the limitations of StratusOCT, these factors only account for a small degree of the variation in visual acuity that these patients exhibit. The detection of stronger correlations between retinal anatomy and visual acuity is likely to require the use of more advanced imaging modalities.

Financial disclosure(s): Proprietary or commercial disclosure may be found after the references.

Figure 1

Optical coherence tomography B-scan [A] demonstrating subretinal fluid (SRF) accumulation and pigment epithelial detachment (PED). The clinically relevant boundaries (internal limiting membrane [ILM], outer photoreceptor border, retinal pigment epithelium [RPE], and the estimated normal location of the RPE layer [B]) are graded using OCTOR (computer-assisted manual grading) software, which then computes the volumes of the spaces (retina, SRF, and PED) defined by these boundaries [C].

Figure 2

Scatter plot comparing OCT-derived thickness of the neurosensory retina at the foveal center point with visual acuity (logarithm of the minimal angle of resolution - logMAR), in patients newly diagnosed with neovascular age-related macular degeneration. The solid line represents the regression line and the dotted lines represent the 95% confidence interval for the mean.