Outer retinal tubulation in the comparison of age-related macular degeneration treatments trials (CATT)

Abstract

Purpose: To determine the prevalence of, risk factors for, and visual acuity (VA) correlations with outer retinal tubulation (ORT) seen on spectral-domain optical coherence tomography (SD OCT) in eyes with neovascular age-related macular degeneration (AMD) after anti-vascular endothelial growth factor (VEGF) therapy.

Design: Prospective cohort study within a randomized clinical trial.

Participants: Patients with SD OCT images at weeks 56 and 104 in the Comparison of AMD Treatments Trials (CATT).

Methods: Participants in the CATT were assigned randomly to ranibizumab (0.5 mg) or bevacizumab (1.25 mg) treatment and to a monthly or pro re nata (PRN) injection-dosing regimen. A subset of eyes was imaged with SD OCT beginning at week 56. Cirrus 512×128 or Spectralis 20°×20° volume cube scan protocols were used to acquire SD OCT images. Two independent readers at the CATT OCT reading center graded scans, and a senior reader arbitrated discrepant grades. The prevalence of ORT, identified as tubular structures seen on at least 3 consecutive Cirrus B scans or 2 consecutive Spectralis B scans, was determined. The associations of patient-specific and ocular features at baseline and follow-up with ORT were evaluated by univariate and multivariate analyses.

Main outcome measures: Outer retinal tubulations.

Results: Seven of 69 eyes (10.1%) at 56 weeks and 64 of 368 eyes (17.4%) at week 104 had ORTs. Absence of diabetes, poor VA, blocked fluorescence, geographic atrophy, greater lesion size, and presence of subretinal hyperreflective material at baseline were associated independently with greater risk of ORT at 104 weeks (P < 0.05). Neither drug nor dosing regimen were associated significantly with ORT. The mean VA of eyes with ORT at week 104 (58.5 Early Treatment Diabetic Retinopathy Study letters) was worse than the mean VA of eyes without ORT (68.8 letters; P < 0.0001).

Conclusion: At 2 years after initiation of anti-VEGF therapy for neovascular AMD, ORTs are present in a substantial proportion of eyes. We identified baseline features that independently predict ORTs. It is important to identify ORTs because eyes with ORTs have worse VA outcomes than those without this finding.

Copyright © 2014 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

Figures

Figure 1

Representative images to show structural changes in ORTs over time. (A) ORT (arrow) next to an intraretinal cystoid structure without a hyper-reflective rim at week 56, (B) 9 months later, the ORT and cystoid structure appear to have coalesced into a retinal area with multiple cystoid structures and disrupted layers. (C) At 56 weeks, there was a small ORT overlying an area of retinal elevation (arrow). (D) 3 months later, in this same eye as in (C) the ORT has nearly disappeared, and by (E) 9 months, and (F) 12 months, it is no longer apparent. The width of the atrophic area underlying this ORT, seen as the area with increased choroidal signal penetration, has increased over time (brackets). *ORT = outer retinal tabulation

Figure 2

Representative OCT images at week 56 (A, C, E) and week 104 (B, D, F) in three eyes without ORT at week 56 but with ORT (arrows) at week 104. ORTs are seen adjacent to areas of geographic atrophy, seen as photoreceptor layer thinning above an area of increased light penetration into the choroid (brackets). *ORT = outer retinal tabulation