Insights from Project MACULA: histological correlates of multimodal ex vivo imaging features in human donor eyes with age-related macular degeneration (AMD)

Abstract

 

Purpose

 

To present experience with and examples of ex vivo multimodal imaging of human donor eyes and macula-wide high-resolution histology.

 

Methods

 

Donor eyes from the Alabama Eye Bank with/without AMD pathologies were preserved ≤ 6 hr after death. Series #1 eyes (preserved 1996-2009, n=101) were viewed as excised 8 mm diameter macular punches (retina, RPE, and choroid). Series #2 eyes (preserved 2011-2013, n=155) were viewed with the anterior segment removed. Imaging included: 1. Color photography with epi- and trans-illumination and a ring flash. 2. Using the Spectralis (Heidelberg Engineering, Heidelberg, Germany) and a customized tissue holder (courtesy J. Fischer), volume scan spectral domain optical coherence tomography (SD-OCT) and red-free scanning laser ophthalmoscopy (SLO). Many eyes also underwent infrared SLO and autofluorescence (AF) imaging (excitation: 488 nm and 787 nm). Histology (PMID 21421869) was available for 55 unremarkable maculas, 27 early AMD, 40 neovascular AMD, and 13 geographic atrophy (GA).

 

Results

 

Many advances important in clinical imaging are useful for pathology specimens, including SLO, signal averaging, and volume scans. We developed imaging signatures for subretinal drusenoid deposits (SDD), calcified drusen, outer retinal tubulations (abstracts by Freund et al, Litts et al), GA, and intra-retinal reflective spots, which can be tracked to individual cells (Figure 1). SDD are found best through volume scans and AF.

 

Conclusions

 

Previous AMD grading systems for donor eyes using color photography (PMID 9620067, 15557458) and OCT (PMID 19225801, 22183367) have not incorporated SDD, a major independent risk factor for AMD progression. Multimodal ex vivo imaging is a novel way to identify specific pathologies for laboratory studies while serving as a steppingstone to clinical imaging.

 

 

Figure 1. Ex vivo SD-OCT and histology in exudative AMD eye with massive disciform scar. A. Perifoveal B-scan shows focal hyper-reflectivity associated with subretinal space (pink), the lumen of outer retinal tubulation (yellow), and a large cyst (green). B. Section provides both a panoramic view and cellular resolution. Spots can be followed. C. Rounded pigmented cells (presumed RPE) invade the retina. D. Pigmented cell with lipofuscin granules.

 

Keywords: 412 age-related macular degeneration • 551 imaging/image analysis: non-clinical • 639 pathology techniques