Abstract
Purpose :
Drusen are lipoproteinaceous deposits found between the retinal pigmented epithelium (RPE) and Bruch’s membrane. Soft drusen are amorphous, granular, large (>125) and are associated with age-related macular degeneration leading to vision loss. As drusen grow, they disrupt the RPE by pushing against the cells. The aim of this study is to evaluate RPE viability atop drusen in histopathological sections obtained from enucleated and eviscerated eyes.
Methods :
A total of 158 eyes were obtained from the MUHC-McGill University Ocular Pathology and Translational Laboratory, Montreal, Canada (2013-2019); 79 were enucleated (50%) and 79 eviscerated (50%). The eyes were embedded in paraffin and histopathological sections were obtained. Initial studies were done to identify the eyes with drusen. These were stained using an immunohistochemical panel aimed at RPE identification and viability assessment. The panel includes HMB-45, MelanA (melanocyte markers) and Cytokeratin 8/18 (CK8/18) (epithelial cell marker) for RPE identification. It also includes the polyclonal cytoplasmic stain Ki-67 (Cell proliferation marker), and monoclonal intranuclear stains p53 (cell damage marker), p21 (cell cycle arrest marker), caspase-3 (apoptosis marker), and lipofuscin for viability. Histopathological analysis was done in scanned sections (Zeiss AxioScan.Z1) in eyes with drusen. RPE atop the drusen were compared to normal RPE cells surrounding it.
Results :
Histopathological analysis was performed. The prevalence of drusen was comparable in enucleated (45.6%) and eviscerated (48.1%) eyes and increased with age. Of the 158 eyes, 53 (33.7%) were found to have soft drusen of which we studied 20 (10 enucleated; 10 eviscerated). The cells atop the drusen expressed positivity for CK 8/18 and HMB-45 but were negative for MelanA. Similar results were observed in the undisturbed RPE. As for viability, the intranuclear and cytoplasmic stain positivity reflected the degree of damage to the RPE above the drusen in concordance with the presence of lipofuscin.
Conclusions :
The histopathological study of drusen and RPE is possible in enucleation and evisceration patient samples. Our immunohistochemical panel identified the cells overlying drusen as RPE cells. Damage to the RPE overlying drusen was quantified and qualified by intranuclear and cytoplasmic stain positivity and compared to the state of the undisturbed RPE.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.