Outer retinal tubulation as a predictor of the enlargement amount of geographic atrophy in age-related macular degeneration

Purpose: To determine the prognostic value of outer retinal tubulation (ORT) in the enlargement amount of geographic atrophy (GA) in eyes with age-related macular degeneration (AMD).

Design: Cohort study.

Participants: One hundred eight fellow untreated eyes of 143 patients with GA resulting from AMD enrolled in the MAHALO study (clinicaltrials.gov identifier, NCT01229215) who completely satisfied the study term and had gradable spectral-domain optical coherence tomography (OCT) images obtained at both baseline and month 18 visits.

Methods: The MAHALO study enrolled 143 subjects into a phase 1b/2 multicenter, randomized, single-masked, sham-injection controlled clinical trial of the safety, tolerability, and evidence of activity of lampalizumab in patients with GA associated with AMD. Spectral-domain optical coherence tomography images were obtained at multiple time points in both eyes, although only the baseline and month 18 data of the fellow (nonstudy) eyes were considered in this exploratory analysis. The Cirrus HD-OCT review software was used for automatic segmentation and measurement of GA areas, with manual correction of segmentation errors by certified OCT graders. Baseline OCT images also were assessed for the presence of ORT. The enlargement amount of GA in eyes with ORT was compared with that of eyes without ORT.

Main outcome measures: Comparison of the enlargement amount of GA in eyes with and without ORT.

Results: Twenty-four of these 108 eyes demonstrated evidence of ORT. The amount of enlargement of GA in eyes with ORT was significantly slower than that of eyes without ORT (1.85±0.78 vs. 2.67±1.61; P = 0.001). This difference remained significant when considering subgroups with unifocal or multifocal GA lesions, because eyes with ORT in both subgroups had a slower enlargement amount of GA than eyes without ORT (2.91±1.70 vs. 2.08±0.88 [P = 0.01], in eyes with multifocal GA lesions; and 2.24±1.40 vs. 1.63±0.57 [P = 0.02], in eyes with unifocal GA lesions).

Conclusions: In eyes with ORT, GA lesions seem to enlarge at a significantly slower rate than those of eyes without ORT. The presence of ORT may need to be accounted for in longitudinal studies of GA.