Abstract
Purpose:
The Minnesota Grading System (MGS) is a useful methodology to correlate the phenotype of eye bank eyes with age-related macular degeneration (AMD) with secondary analysis (Olsen et al., IOVS, 2004). In this study, we scored a group of eye bank eyes using the MGS and correlated the score with histopathologic, immunohistochemical (IHC), ultrastructural, and genetic findings.
Methods:
Eye bank eyes from the Lions Eye Institute for Transplantation and Research (LEITR) were utilized. Four donors with AMD were graded using the MGS. One eye from each donor pair was dissected and the retina was removed to acquire a fundus photo of the exposed retinal pigment epithelium (RPE). Tissue was removed for genetic studies. The fellow eye from each pair was submitted for histopathologic evaluation. The eyes were serially sectioned (7µm) through the macula and alternatively stained with hematoxylin and eosin, Masson trichrome, periodic acid-Schiff. Individual slides were examined and a two-dimensional (2d) reconstruction of the topography of the macula was created and compared with the MGS. Select unstained slides were used for IHC staining. In one donor, portions of tissue were obtained for electron microscopic (EM) processing.
Results:
One donor was MGS 1, one was MGS 2 and two were MGS 3. The MGS 1 donor graded fundus photo and histology with 2d reconstruction showed rare hard (nodular) drusen. The MGS 2 donor contained more numerous hard (nodular) drusen measuring up to 63µm in diameter with total areas of up to 250µm. One MGS 3 eye was found on fundus photo examination to contain reticular pseudodrusen (RPD). Histologic evaluation, 2d reconstruction and EM showed that eye to contain diffuse, grade 3 basal laminar deposit (BLD) with focal nodules of material surfaced by RPE that corresponded to the RPD. The other MGS 3 eye contained BLD, soft drusen and occult choroidal neovascularization (CNV) underlying the RPE. IHC results showed inflammatory cells in the choroid underlying the BLD and CNV that were positive for CD68 and negative for CD3 and CD20.
Conclusions:
Eye bank eye fundus photos evaluated by the MGS correlated with histologic and ultrastructural findings in MGS 1, MGS 2 and MGS 3 grades of AMD. One MGS 3 eye contained an area of occult CNV. Another MGS 3 donor with RPD suggests that the location of the RPD is deep to the RPE and adjacent to BLD, rather than subretinal.