Purpose
To study the ultrastructure of choroidal neovascular vessels (CNV) of age-related macular degeneration (AMD) donor eyes and their influence on the surrounding tissue.
Methods
Perimacular sections of eight late wet AMD donor eyes (mean age 81+/- 10 years) were investigated with light and electron microscopy. The ultrastructures of neovascular and non neovascular vessels were analyzed with respect to pathological alterations. Signs for pathology were e.g. extreme swelling of endothelial cells, collapse of luminal space, invasion of endothelial projections into the vessel lumen building a labyrinth-like structure, changes in fenestration, necrotic cells or loss of cell junctions. We tried to discriminate perfused from not perfused vessels by morphological criteria and presence of erythrocytes, e.g. leaky vessels which did not show an edema or blood leakage were judged to be non-perfused if they did not show a thrombotic reaction.
Results
The donor eyes showed different stages of destruction, ranging from areas with normal subretinal ultrastructure to areas with retinal scars. In 33 % of the sections showing occult CNV, we found small sites of functional neovascular vessels which were in close distance to groups of locally surviving photoreceptors (yellow vessels in Fig. 1). In contrast, areas with retinal scars were associated with probably non-perfused damaged vessels (red vessels in Fig. 1).
Conclusions
It is supposed that intact CNV in late AMD are formed in a kind of wound healing reaction to facilitate retinal metabolism and survival. Only if CNV vessels became unfunctional and/or leaky, edema is formed causing photoreceptor death. Only this stage can be diagnozed by an ophthalmologist during patient care. Whether also in early AMD subclinically neovascularization may support photoreceptor survival remains to be investigated.
Keywords: 412 age-related macular degeneration •
436 blood supply •
453 choroid: neovascularization