Abstract
Purpose:
To characterize drusen morphology and retinal layer abnormalities by simple, ordinal description and to associate these features with drusen progression over one year on SD-OCT scans.
Methods:
Twenty two pairs of SD-OCT macular volume scans at baseline and year 1 from eyes with age related macular degeneration (AMD) were registered by the manufacturer algorithm and evaluated independently. Absence of neovascular AMD was confirmed by OCT and FA at both visits. For each eye, the corresponding B scans passing through the fovea were identified at each of the two visits and a grid was placed to divide the B scan into 8 lateral segments. Each segment was then evaluated for presence of drusen and drusen morphology including number, height, shape and internal reflectivity of drusen. Abnormalities in the inner segment outer segment (IS-OS) junction, and retinal pigment epithelium (RPE) were evaluated.
Results:
Among 176 segments of 22 B scans evaluated at baseline, 85 segments had drusen. Of these, 21 showed increase in maximum height of drusen at year 1, 53 showed no change, 4 showed decrease and 7 had complete disappearance of drusen. Of the 91 segments without drusen, 16 developed drusen at year 1. The baseline features of drusen that were associated with increase in height at year 1 compared to those that did not change were small size less than 50 µm (76% vs 62%), patchy IS-OS (86% vs.79%), IS-OS fused to underlying druse (57% vs 45%) and mixed reflectivity within druse (57% vs 44%). The features of baseline segments that developed new drusen at year 1compared to those that did not were patchy IS-OS (44% vs 13%), IS-OS elevation (25% vs 1%) and patchy RPE (50% vs 21%).
Conclusions:
IS-OS and RPE abnormalities were positively associated with drusen development as well as drusen size increase. Our study described drusen morphological characteristics in an effort to develop evaluation criteria to follow the disease progression in non neovascular AMD. Such characterization may supplement drusen volume assessments from SD OCT for purposes of estimating risk.
Keywords: 412 age-related macular degeneration •
504 drusen