Widefield Megahertz (MHz) OCT of diabetic retinopathy

Abstract

 

Purpose

 

To investigate morphological appearance of diabetic retinopathy and laser effects in panretinal laser photocoagulation with a widefield MHz OCT (60° field of view, 120° center angle).

 

Methods

 

A custom swept-source OCT device with a 1060nm Fourier-domain mode-locked laser source achieving a line rate of 1.68MHz was used to investigate 15 consecutive patients with diabetic retinopathy. Within 1.82s datasets consisting of 2088x1024 A-scans over 60° were acquired. The densely sampled three dimensional datasets were investigated in various B-Scan cross-sections as well as en-face images and 3D reconstructions. Selected findings were compared with SLO images from a widefield SLO (Optos, Dunfermeline, UK).

 

Results

 

On the densely sampled 3D and en-face images, hard exsudates, peripheral laser spots as well as proliferative neovascularization were readily detected. Characteristic structural changes resulting from laser burns could easily be visualized across the whole field of view in the OCT datasets. In addition, depth-scans and B-scans allowed to identify additional structural changes including IS/OS disruption, RPE detachment or neovascularisation reaching into the vitreous across the field of view.

 

Conclusions

 

Three dimensional visualization of the retina over 60° field of view with a MHz OCT is feasible in patients with diabetic retinopathy. It might allow additional clinical insights in peripheral changes such as laser spots or retinal neovascularisation.

 

 

3D reconstruction of OCT dataset of patient with diabetic retinopathy with neovascularization (green), hard exsudates (yellow), epiretinal membrane and peripheral retinal scars after panretinal laser treatment (blue). Indications with arrows are examplatory.

 

 

Top: En-face of same patient as in figure 1. Red line indicates the position of B-Frame below. Retinal scars due to focal laser coagulation temporal of the fovea visible. Bottom: Neovascularisation (green) reaching into the vitreous is visible on the left side. Retinal scars especially on RPE level due to panretinal laser treatment (blue) are observable.

 

Keywords: 552 imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • 578 laser • 499 diabetic retinopathy