Outer Retinal Tabulation
The purpose of this prospective cohort study within a randomized clinical trial was to determine the prevalence of, risk factors for, and visual acuity correlations with outer retinal tubulation (ORT) seen on spectral-domain optical coherence tomography in eyes with neovascular age-related macular degeneration after anti-vascular endothelial growth factor therapy.
Patients with SD-OCT images at weeks 56 and 104 in the Comparison of AMD Treatments Trials were assigned randomly to ranibizumab (0.5 mg) or bevacizumab (1.25 mg) treatment and to a monthly or pro re nata 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 three consecutive Cirrus B scans or two 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. Outer retinal tubulations were the main outcome measures.
It was noted that 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 hyper-reflective material at baseline was associated independently with greater risk of ORT at 104 weeks (p<0.05). Neither drug nor dosing regimen were associated significantly with ORT. Furthermore, 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).
To conclude, two years after initiation of anti-VEGF therapy for neovascular AMD, ORTs are present in a substantial proportion of eyes. This study 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.