Abstract
Purpose :
To investigate retinal pigment epithelium (RPE) appearance in vivo in healthy volunteers and patients with retinal disease with near-infrared autofluorescence (NIRAF) adaptive optics scanning laser ophthalmoscopy (AOSLO) using a 757 nm excitation source.
Methods :
We recently showed that NIRAF excited at 757 nm and collected in an emission band from 778–810 nm produces a robust NIRAF signal, presumably arising from melanin, that reveals the typical hexagonal mosaic of RPE cells at most eccentricities in normal eyes (Grieve et al Biomed Opt Express Nov 2018). In this extension to our initial study, we evaluated the use of this setup on an expanded cohort of normal volunteers and patients with retinal diseases, including: drusen (n=3), geographic atrophy in dry age related macular degeneration (n=8), radiation retinopathy (n=2), central serous retinopathy (CSR) (n=3), Multiple Evanescent White Dot Syndrome (MEWDS) (n=1), and retinitis pigmentosa (RP) (n=1)
Results :
RPE cell densities in normals were consistent with the literature. RPE cell contrast was highest when the excitation beam was focused on the photoreceptors in the confocal channel. Since photoreceptors remain visible at several focal planes, we found that RPE cell contrast was best at the most sclerad photoreceptor focal plane. A diversity of altered NIRAF structure morphometries were seen in patients, including: disruption of the RPE mosaic over drusen, diffuse hyper NIRAF signal with loss of individual cell delineation in a dry age related macular degeneration, increased visibility of the RPE mosaic under an area of photoreceptor loss in radiation retinopathy, hyper NIRAF clumps in a case of CSR and a hypo NIRAF zone collocated with detachment in another case of CSR, hypo NIRAF collocated with a lesion in MEWDS, and perfect correspondence of RPE cell mosaics in reflectance and NIRAF modes in an area of absent photoreceptors in RP.
Conclusions :
Imaging of the RPE mosaic in normals and patients showed efficient signal excitation and detection using NIRAF AOSLO at 757 nm excitation. The structure of the typical hexagonal RPE mosaic seen in normals was altered in retinal disease with diverse morphometries seen in a variety of retinal diseases. NIRAF in AOSLO shows promise as a safe and robust means to evaluate RPE pathology at the level of single cells in numerous retinal disease states.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.