Author: Kiyoko Gocho (France)
Co-authors: Elena Gofas, Celine Chaumette, Christophe Rondeau, Kate Grieve, Michel Paques
Purpose
Retinal pigment epithelium (RPE) cell mosaic can be resolved in the living retina using an adaptive optics (AO) system with transscleral illumination (TSI), as recently shown by Laforet et al. The combination of autofluorescence imaging with adaptive optics scanning laser ophthalmoscopy (AF-AOSLO) has also led in the past to the precise imaging of the RPE mosaic, as reported by our group (K. Grieve et al). The present study evaluates the RPE cells mosaic in the normal retina and other clinical features such as pigment clumps in patients with age related macular degeneration (AMD) and Stargardt disease, using with a commercially available flood-illumination AO retinal camera modified by the addition of TSI, and compared with AF-AOSLO images.
Setting/Venue
Patients were recruited and examined at the clinical investigation center 1423 in the National Quinze-Vingts Ophthalmology Hospital, Paris in France. The procedures used in this study conformed to the tenets of the Declaration of Helsinki, and they were approved by our local ethics committee. A written informed consent was obtained from each subject.
Methods
An infrared LED projector was attached to an AO retinal camera (rtx1-e, Imagine Eyes, France) in order to illuminate the retina with an 850 nm beam focused at the pars plana. This system illumination is composed of two led arrays illuminating the retina through the sclera on both sides of the pupil. The system complied with ANSI regulations. The oblique trans illumination of the posterior retina leads to the generation of phase images that could show the boundaries of the RPE cells. These images were averaged using customized ImageJ software. Infrared AF AOSLO images were registered to TSI images. For AMD and Stargardt disease cases, conventional multi-imaging, including infrared scanning laser ophthalmoscopy (IR SLO), IRAF SLO, SD-OCT (Spectralis), AO-SLO (PSI, USA), AO fundus camera was performed.
Results
We have currently imaged 3 normal subjects, aged between 28 and 56 years, 3 AMD patients and a Stargardt disease patient. In three normal eyes, circular cell-like structures with dark centers surrounded by brighter rings were visible in almost all images. At eccentricities beyond 5 degrees, cell-like structures were visible in the entire field of images. Cell density ranged between 4.4x10^3 and 6.2x10^3 cell/mm^2 across subjects, which showed good correlation with AF AOSLO results and lie within the ranges reported in the literature. In AMD and Stargardt eyes, pigment clumps were visible in the pathological area with a high contrast.
Conlusions
The implementation of TSI on an AO camera allowed visualization and quantification of the RPE mosaic in healthy subjects. The RPE images taken by TSI and AF AO-SLO were similar in shape and density. In pathological eyes, pigment clumps are electively detected with a high contrast. TSI could thus be a valuable addition to a conventional trans-pupillary flood-illumination AO camera, not only for seeing the RPE cells, but also for detecting clinical features such as pigment clumps.
Financial Disclosure
Christophe RONDEAU is employee of Imagine eyes
Comments
-
