Comparison of standardized color photography grading and SDOCT volume analysis in intermediate age-related macular degeneration to predict 2-year visual acuity outcomes

Abstract

 

Purpose

 

To compare color fundus photography (CFP) macular surface area grading of drusen and geographic atrophy (GA) with spectral domain optical coherence tomography (SDOCT) volume analysis of drusen and retinal pigment epithelium abnormal thinning (RAT) for predicting visual acuity (VA) after 2-year follow-up.

 

Methods

 

Eyes with intermediate age-related macular degeneration (AMD) were enrolled in the prospective Age-Related Eye Disease Study 2 (AREDS2) Ancillary SDOCT Study. After semi-automated SDOCT segmentation, macular drusen and RAT volumes were calculated in AMD eyes based on a normative SDOCT database of 115 healthy age-controlled eyes. Same-visit AREDS2 CFP drusen area score grading (scale 0-7) and CFP GA disc area grading were performed in AMD eyes. Baseline measurements were compared with 2-year VA outcome by logistic regression analysis with 95% confidence intervals (CI) and Spearman rank correlation (ρ).

 

Results

 

265 intermediate AMD eyes with baseline CFP and SDOCT analysis were included. On CFP, mean (± standard deviation) drusen area score was 6.1 ± 1.1 (non-linear measurement of mean drusen area was 1.17 ± 0.66 mm²) and mean GA area was 0.11 ± 0.50 disc areas (non-linear measurement of mean GA area was 0.19 ± 0.88 mm²). On SDOCT analysis, mean drusen volume was 0.084 ± 0.160 mm³ and mean RAT volume was 0.8 ± 2.1x10^-3 mm³. Of 239 eyes followed to year 2, mean final VA was 77 ± 13 ETDRS letters. VA correlated with 1.3 letter decrease (CI=2.8-0.2) per 1-unit increase in drusen score (ρ=-0.16, p=0.014), 3.1 letter decrease (CI=6.1-0.1) per 1-disc area increase in GA area (ρ=-0.16, p=0.012), 1.3 letter decrease (CI=2.4-0.31) per 0.1-mm³ increase in drusen volume (ρ=-0.21, p<0.001), and 0.91 letter decrease (CI= 1.65-0.18) per 0.001-mm³ increase in RAT volume (ρ=-0.20, p=0.002).

 

Conclusions

 

CFP and SDOCT measurements of intermediate AMD were significant baseline predictors of VA after 2-year follow-up. SDOCT drusen and RAT volume had greater correlation coefficients for predicting VA than CFP drusen area score and GA area, respectively. However, CFP and SDOCT measurements did not yield precise linear correlations with VA (Spearman ρ<0.25 for all measurements). Longer follow-up may show better correlations with VA.

 

Keywords: 412 age-related macular degeneration • 552 imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)