Optical Coherence Tomography Angiographic Features of Non-neovascular Age-related Macular Degeneration

Abstract

 

Purpose

 

To describe features of non-neovascular age-related macular degeneration (AMD) using a novel imaging technique with unique ability to demonstrate inner choroidal blood flow.

 

Methods

 

Eyes of patients with intermediate AMD or geographic atrophy were imaged using color fundus photography, autofluorescence, and high speed (100K A-scan/sec) 1050 nm swept-source OCT. Flow was detected using the split-spectrum amplitude-decorrelation angiography (SSADA) algorithm and segmented at the level of the Bruch’s membrane to show choroidal and retinal flow separately. OCT angiography, which demonstrates flow signals in both en face and cross-sectional orientation, was then correlated with conventional imaging for localization and analyzed.

 

Results

 

OCT angiography shows loss of flow signals in the inner choroid in the area of geographic atrophy (GA). At the border of GA, an area with absent retinal pigmented epithelium (RPE) and photoreceptors with preserved inner choroidal flow is present (Figure 1). In an eye with large confluent drusen, the inner choroidal flow signal is variably attenuated, not necessarily correlating with the height of the RPE-drusen complex (Figure 2). In normal, age-controlled eyes, a uniform inner choroidal blood flow was detected throughout the macula.

 

Conclusions

 

OCT angiography is a novel imaging technique that can demonstrate local inner-choroidal blood flow, which was previously not possible with in-vivo imaging techniques. The study showed loss of inner choroidal flow in the area of GA, consistent with the histologic descriptions. Presence of intact inner choroidal flow near a border of GA in an area of RPE and photoreceptor loss may suggest choriocapillaris loss may be a secondary pathology. The finding of variable loss of inner choroidal flow in intermediate AMD may add to our understanding of mechanism of progression to advanced AMD. A larger cohort with prospective data will be helpful in determining the utility of OCT angiography in AMD.

 

 

Cross-section A demonstrates loss of inner choroidal flow in the area of geographic atrophy. At the temporal edge of atrophy, an area of RPE and photoreceptor loss with intact inner choroidal flow is present.

 

 

Figure demonstrates variable loss of inner choroidal flow which does not correlate necessarily with the height of the overlying RPE-drusen complex. An area of shortened photoreceptor outer segments is present in the larger druse.

 

Keywords: 552 imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • 550 imaging/image analysis: clinical • 412 age-related macular degeneration