Drusen volume development and progression towards advanced AMD

Abstract

Purpose : The aim of this prospective study was to analyze drusen volume development preceding progression towards advanced age-related macular degeneration (AMD).

Methods : 120 patients with early or intermediate AMD were scanned using Spectralis SD-OCT (scanning area 20°x20°, volume scan 1024x97) in a regular follow-up scheme of every three months for at least one year. The standard ETDRS grid was centered on the fovea and the drusen volume for each ETDRS-field was automatically segmented by a software. Progression towards advanced stages of AMD was noted as end point of the study, either by signs of atrophy or fluid within the B-scans or CNV in the respective fluoresceine angiography.

Results : 17 eyes converted to advanced AMD during follow-up, 7 to geographic atrophy (GA), 10 to wet AMD. GA was consistently preceded by a drusen regression. The mean time between regression and first atrophic features in the B-scans was 12 months (SD 4.6, range 6-18). The drusen volume until regression grew continually until a max. volume of 0.24mm³ (SD 0.03, range 0.19-0.25), with one eye having a large drusenoid pigmentepithelial detachment (volume 0.88mm³). The mean drusen volume at the stage of first atrophic signs was 0.12mm³ (SD 0.04, range 0.09-0.19). With wet AMD, mean max. drusen volume before progression was 0.32mm³ (SD 0.16, range 0.18-0.47). A preceding regression of total drusen volume occurred in 8 of 10 eyes, with a mean time period of 11.1 months between regression and CNV (SD 4.5, range 6 – 18). Evaluating the focal drusen volume development in the single ETDRS-fields, all 10 eyes showed regression in the same field that developed CNV at a later time point.

Conclusions : A focal regression of drusen volume was observed in all 17 eyes before conversion towards advanced stages of AMD. However, with drusen regression being a frequent event and the mean time between regression and first clinical signs of advanced AMD being about one year, drusen regression alone seems to be an insufficient biomarker for immediate progression of disease. Therefore, the trigger for drusen regression and the pathomechanisms during the time to conversion need to be clarified.

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.