OCTA detects flow alterations in the choriocapillaris underlying drusen in non-exudative age-related macular degeneration without geographic atrophy

Abstract

Purpose : The purpose of this study is to use en face optical coherence tomography angiography (OCTA) to investigate the flow characteristics of the choriocapillaris (CC) underlying drusen and to correlate these flow alterations with structural alterations of the retinal pigment epithelium (RPE) in patients with non-exudative age-related macular degeneration (AMD) without geographic atrophy (GA).

Methods : OCTA imaging was performed using a 1050nm, 400kHz swept-source (SS)-OCT system in 35 eyes of 26 patients with non-exudative AMD without GA (77.5±9.0 years; 11 males; 15 females). CC flow alteration maps were constructed by binarizing en face OCTA CC slabs. Structural RPE alteration maps were constructed by binarizing sub-RPE slab projections. The spatial relationships between CC flow alterations and RPE alterations were then evaluated by overlaying these two alteration maps.

Results : Figure 1 shows representative data suggesting a spatial relationship between RPE alterations and CC flow alterations. Some, but not all, drusen are associated with CC flow alteration.

Conclusions : A combination of en face slab OCT structural maps and OCTA flow maps were used to associate structural alterations of the RPE to flow alterations of the CC. These observations confirm the mutualistic relationship between the RPE and the CC. Continuing work will investigate methods to quantitate these associations.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.

 

Images from a 78 y/o Caucasian female with non-exudative AMD. (A) Color fundus photo showing large drusen associated with pigmentary changes. (B) Late stage FA showing hyperfluorescence due to drusen staining. (C) Red free photo showing drusen hypereflectivity; purple box indicates the 3mm x 3mm OCT field. (D) Enlargement of (C) corresponding to the OCT field. (E) OCTA projection of retinal vasculature. (F) OCT B-scan taken from the blue line in (E), showing a drusenoid pigment epithelial detachment; yellow-green lines demarcate the sub-RPE slab, shown in (H); yellow-orange lines demarcate intensity CC slab, shown in (I). (G) Unthresholded OCTA B-scan; yellow-orange lines, matching those in (F), demarcate the OCTA CC slab shown in (J). (K) Binarized sub-RPE slab; white indicates increased light penetration. (L) Binarized CC slab; black indicates CC alteration. (M) Semi-transparent overlay of (K) onto (L); red indicates increased light penetration. Scale bars: 1mm.