Age-related macular degeneration and risk factors for the development of choroidal neovascularisation in the fellow eye: a 3-year follow-up study

Abstract

Introduction: The presence of large-sized drusen (≥125 μm), soft indistinct drusen, pigmentary changes, a large area of drusen and a choroidal neovascular membrane in one eye have been found to be predictive risk factors of late exudative age-related macular degeneration (AMD). Multimodal imaging potentially increases the possibility of indentifying further potential risk factors of developing wet AMD.

Purpose: To identify morphological and/or functional baseline risk factors for the development of choroidal neovascularization (CNV) in a multimodal set of images from fellow eyes of patients with exudative AMD.

Methods: Single-center, prospective, observational, longitudinal 2-year plus 1-year extension study of 62 patients with neovascular AMD in one eye (the nonstudy eye) and early age-related maculopathy (ARM) in the fellow eye (study eye). Best-corrected ETDRS visual acuity, fluorescein angiography (FA) and indocyanine green angiography (ICG), fundus photography, retinal leakage analysis, fundus autofluorescence imaging and optical coherence tomography (OCT Stratus 4.0.2, Carl Zeiss Meditech Inc.) were performed at baseline and every 6 months in order to identify both conversion to CNV as well as possible predictive features present before conversion. A semiautomated computer-assisted grading system was used for classifying fundus color images. Only eyes with 3 years of follow-up were considered for statistical analysis.

Results: Fifty-two patients completed the 3-year study follow-up: 26 men and 26 women aged from 56 to 92 years (mean ± SD: 76 ± 6 years). CNV confirmed with FA developed in 46% of the 52 study eyes during the 3-year follow-up (24 converted eyes: 7 in the first year, 11 in the second and 6 in the third). A significantly higher risk for conversion to wet AMD was found only for leakage on a retinal leakage analyzer (odds ratio, OR = 5.0; 95% confidence interval, CI = 1.5-16.4; p = 0.006) detected at least in one visit before the onset of exudative lesions, for baseline ICG hot spots (OR = 7.2; 95% CI = 2.0-25.7; p = 0.002), baseline late ICG hot spots (OR = 4.7; 95% CI = 1.4-15.4; p = 0.009) and baseline early ICG hypofluorescent spots (OR = 3.7; 95% CI = 1.2-12.1; p = 0.025). The total area of drusen, the area of drusen in subfield 1, inner circle or outer circle, the total number of drusen and the number of drusen ≥125 μm, fundus autofluorescence patterns, OCT findings and the severity of ARM at baseline did not show any correlation with an increased risk of conversion to wet AMD.

Conclusion: At 3 years, progression from early to late exudative AMD was superior to the expected rate (44%). ICG early and late hyperfluorescent spots or areas, ICG early hypofluorescent spots or areas and early leakage detected with the retinal leakage analyzer, but not pigmentary changes, large drusen, number and area of drusen at any location or a greater severity of ARM at baseline, showed to be a predictive parameter of conversion to wet AMD.