Bilateral evolution of OCT biomarkers in dry AMD: long-term follow up study

Abstract

Purpose : Age related-macular degeneration (AMD) is a disease that often presents bilaterally, although there have been limited studies in long term progression of Spectral Domain Optical Coherence Tomography (SD-OCT) biomarkers comparing two eyes in the same patient. The aim of the study was to compare progressive OCT changes between two eyes among subjects with dry AMD over a period of 5.7 years.

Methods : We performed a retrospective imaging study on the volumetric SD-OCT of 33 patients (66 eyes) with bilateral dry AMD with a minimum follow-up of at-least 4 years. Yearly OCT scans were evaluated for emergence and progress of four late dry AMD characteristics: iRORA, cRORA, drusen ooze and drusen collapse. Statistical analysis was done using Microsoft Excel. Univariate analysis was done for the various characteristics at baseline.

Results : Patients with a mean age of 77.2 ± 10 years were followed up for a total of 68.7 ± 21.5 months. At baseline, iRORA, cRORA, drusen ooze was present in 12.1%, 15.2% and 21.2% of the patients, respectively. At the final follow up iRORA, cRORA, drusen ooze was present in 27.3%, 48.5% and 57.6% of the patients, respectively. Bilateral drusen ooze was present in 9.1% of the patients at baseline. 15.2% of the patients had bilateral drusen ooze at the final follow up with mean interval of 5.0 ± 1.4 years between the two eyes. Bilateral iRORA was present in none of the patients at baseline. 9.1% of the patients had bilateral iRORA at the final follow up with a mean interval of 4.7 ± 2.1 years between the two eyes. Bilateral cRORA was present in 9.1% of the patients at baseline. 18.2% of the patients had bilateral cRORA at the final follow up with mean interval of 1.7 ± 0.6 years between the two eyes. By the final follow-up 9/33 (27.2%) and 6/33 (18.1%) of the patients had evidence of drusen collapse in unilateral and bilateral eyes, respectively. For patients with observed drusen collapse bilaterally, the mean interval was 2.2 years.

Conclusions : Any single OCT biomarker such as cRORA, iRORA, drusen ooze and drusen collapse is seen bilaterally in a minority (less than 22%) of the patients with dry AMD at presentation. Even over a long-term follow-up, only 36.4% of the patients showed at-least one bilateral biomarker over a period of 5.7 years. In patients with bilateral OCT biomarkers, cRORA had the shortest mean interval in appearance between the two eyes.

This is a 2021 ARVO Annual Meeting abstract.