Visualization of transretinal blood flow in retinal angiomatous proliferation with phase-resolved Doppler-OCT

Abstract

 

Purpose

 

To visualize intra- and transretinal blood flow in patients with retinal angiomatous proliferation (RAP) using high resolution Doppler-OCT. Advanced stages of RAP respond better to a combination therapy with photodynamic therapy and intravitreal anti-VEGF or triamcinolone than to anti-VEGF monotherapy which is the standard treatment for the more common classic or occult choroidal neovascularisations (CNV) in age-related macular degeneration. It is important to accurately identify abnormal intraretinal blood flow consistent with RAP to optimize the treatment strategy.

 

Methods

 

Consecutive case series of ten treatment-naïve patients, median age 79 years (range 65-90), diagnosed on fluorescein angiography (FA) and/or indocyanine-green angiography (ICG) with an RAP lesion in one eye. Patients were imaged with an experimental 1050 nm swept-source phase-resolved Doppler-OCT instrument. To considerably improve Doppler sensitivity, imaging was performed with backstitched B-scans [Braaf B et al, Opt. Express 2012]. Abnormal flow consistent with RAP was defined as intraretinal (intraretinal neovascularisation, IRN) or transretinal (retinal choroidal anastomosis, RCA).

 

Results

 

An example of a patient with RCA and subretinal CNV is presented in the figure. In all ten patients abnormal flow on Doppler-OCT was detected. In 5 patients an RCA was found, 3 patients showed an IRN and in 2 patients only a CNV was seen with flow limited to the subretinal space or located in a pigment epithelial detachment.

 

Conclusions

 

We were able to visualize intra- and transretinal blood flow consistent with RAP in 8 out of 10 patients. This data in RAP patients shows the significant clinical potential of angiography with Doppler-OCT to accurately distinguish between intra- and subretinal neovascularisations.

 

 

Fig. Early FA (A) shows two hyperfluorescent vascular networks, the smaller one suggestive for RAP, the larger for classic CNV. The red square on FA indicates the Doppler-OCT scan grid. The Doppler enface image (B) shows absolute phase-differences (white) due to blood flow, the red asterisks indicate an abnormal vascular network. The red lines indicate the location of the Doppler tomograms (C1,2). In the tomograms the flow (red) was projected over structural B-scans. The tomograms demonstrate the cross-sectional representation of transretinal blood flow (RCA, C1) and flow extending from the choroid (CNV, C1,2).

 

Keywords: 700 retinal neovascularization • 552 imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • 412 age-related macular degeneration