Abstract
Purpose :
Fundus autofluorescence (FAF) imaging is often used in diagnosis for dry age-related macular degeneration (dAMD). The purpose of this study is to detect the retinal pigment epithelium (RPE) damage using FAF imaging in an animal model and validate the correlation between FAF and other functional evaluation items.
Methods :
Thirty or 35 mg/kg sodium iodate (NaIO3) was injected intravenously into Brown Norway rats to induce RPE degeneration. FAF images were obtained on 2, 5, and 8 days after NaIO3 treatment and the RPE degeneration area was quantified. The a, b, and c-wave amplitude of electroretinogram (ERG) were recorded for at least 1 hour after the onset of dark-adaption. In vitreous fluorophotometry (VFP) evaluation, fluorescein was injected intravenously and, after circulating for 2 hours, the fluorescein concentration of vitreous humor was measured by Fluorotron Master to evaluate the outer blood-retinal barrier (BRB) function. The retinal sample was histopathologically observed with hematoxylin and eosin (HE) staining and immunostaining of ZO-1 and RPE65. To examine its effects on the NaIO3 rat model, N-acetyl cysteine (NAC) was administrated intravitreally 30 minutes prior to NaIO3 injection.
Results :
Compared to normal rats, NaIO3 rats showed numerous dark spots in the FAF image, indicative of RPE damage. The RPE degeneration area was correlated with reduction of each ERG wave amplitude, dysfunction of outer BRB, and retinal structure changes. In addition, RPE protection by NAC on NaIO3-induced RPE degeneration rat model was confirmed by the quantification of damaged RPE area in the FAF image, and it was consistent with the results of ERG and VFP measurements.
Conclusions :
This study demonstrates that FAF is useful to observe the RPE and evaluate the efficacy of RPE protection in vivo rat eye. Using FAF imaging, RPE function of the same sample can be evaluated at several time points. This is an advantage compared to invasive methods such as histopathological examination which is generally used in non-clincial studies.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.