Progression of Outer Retinal Tubulation Volume in Eyes with Geographic Atrophy due to Age-related Macular Degeneration

Abstract

Purpose : To evaluate the change over time in outer retinal tubulation volume in eyes with geographic atrophy secondary to age related macular degeneration.

Methods : One hundred and thirty eyes of 130 subjects with geographic atrophy secondary to non-exudative age related macular degeneration were enrolled in this IRB approved retrospective study. Spectral domain optical coherence tomography (SD-OCT, Zeiss meditech, USA) volumes scans (6X6 macular cube with 512 A-scans and 128 B-scans) of first visit (baseline) and 2 years follow up were collected from the Doheny Eye Institute/UCLA. Baseline OCT images were assessed for the presence of outer retinal tubulation (ORT). SD-OCT scans of the baseline and 2 years visits of the cases that showed ORT at baseline were imported into a custom OCT grading software program (3D-OCTOR). Two independent certified graders manually graded the boundary of the circular cross sections of the tubules, which were seen as hyporeflective spaces with hyperreflective rims. Software then computed the volume of the tubules. Mean ORT volume at baseline and 2 years was compared using a paired t test.

Results : Twenty-four out of 130 eyes demonstrated ORT at both baseline and at 2 years. The total volume of ORT lesions at the baseline and 2 years visits for all 24 cases was 0.039 ± 0.016 mm³ (range, 0.070 – 0.015 mm³) and 0.037 ± 0.013 mm³ (range, 0.060 – 0.020 mm³) respectively. The difference between these two volumes was not statistically significant (p=0.58).

Conclusions : In eyes with GA that also had ORT at baseline, the volume of the tubules did not change over time. This suggests that eyes with GA and ORT at baseline, the ORT are likely end-stage and further progression of ORT volume is unlikely. This has therapeutic implications, and suggests that the measurement of ORT volume may not be a viable biomarker for progression of disease.

This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.