Abstract
Purpose :
Functional deterioration of retinal photoreceptors might be detectable earlier than structural changes and precede clinical signs in retinal diseases. Intrinsic optical signals (IOS) have been proposed as a biomarker for photoreceptor function and optical coherence tomography (OCT) has been employed for their assessment, providing some compelling results. We investigated changes in the outer retina after stimulation with visible light using a commercial OCT platform.
Methods :
The retina of a healthy young subject was imaged using a Cirrus 4000 HD-OCT system (Zeiss Meditec, Jena, Germany). The scanning region was selected 10 - 20 degrees temporally from the fovea. At first, 15 successive baseline measurements were acquired in ambient light. Thereafter, 15 measurements were performed after white light stimulation. Before the first measurement, the retina was stimulated for five minutes. Before every subsequent OCT measurement, the light exposure lasted for one minute. Data processing was performed in MATLAB (The Mathworks, Inc., Massachusetts, USA) using custom algorithms.
Results :
The distance between IS/OS junction and retinal pigment epithelium (RPE) was calculated based on the measured data sets, before and after white light exposure of the retina. The mean distance after light stimulation was significantly shorter than under ambient light conditions (40.0 μm ± 1.1 µm vs. 44.7 μm ± 0.6 μm; p<0.001). The minimum distance of 6.0 μm was found after eight minutes of cumulative light exposure and led to a merging of the reflective bands of the RPE and the photoreceptor outer segment tips (Figure 1).
Conclusions :
Changes in the outer retinal layer as a response to a long white light stimulus could be observed using a commercially available OCT system and advanced software. Furthermore, the merging of the reflective bands of the outer segment tips and the RPE indicates that the observed change is not a result of a change in the photoreceptor outer segment but of a dynamic in the subretinal space.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.