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A.S. Dabholkar, J.–D. Huang, J.B. Presley, M.F. Chimento, C.A. Curcio, M. Johnson; Quick–Freeze/Deep–Etch (QFDE) Study of Bruch’s MembraneFrom Older Eyes: Macula vs Periphery . Invest. Ophthalmol. Vis. Sci. 2006;47(13):1397.
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© ARVO (1962-2015); The Authors (2016-present)
To investigate ultrastructural differences in Bruch's membrane between macular and peripheral regions of older eyes.
Normal human eyes were obtained from 76, 78, 84 and 86 yr old donors and preserved in 2% glutaraldehyde and 1% paraformaldehyde. Macular and peripheral tissue blocks were quick–frozen, oblique–fractured, etched, and shadowed to obtain replicas of Bruch's membrane. Three to 4 replicas from each of 3 to 4 macular and peripheral regions of 3 eyes were examined by transmission electron microscopy (TEM); in two eyes (78 and 86 yr old), a single replica was examined. Tissue specimens were also prepared using thin–section TEM using the OTAP (osmium tetroxide, tannic acid, paraphenylenediamine) post–fixation technique to improve neutral lipid preservation.
Exquisite morphology of Bruch’s membrane was recorded with the peripheral regions showing similar overall appearance to the macula. In all eyes, both regions showed significant accumulation of lipoprotein–like particles (LLP) with more of these particles seen in the macular region as compared to the periphery. In one eye (78 yrs old), a "lipid wall" (a multilayer of packed LLPs) was apparent between the inner collagenous layer (ICL) and the basal lamina of the retinal pigment epithelium in both macular and peripheral regions. In a second eye (86 yrs old), a continuous row of LLPs was seen in these same regions. Few LLPs were seen in the outer collagenous layer in either macular or peripheral samples. Results using OTAP showed excellent agreement with those seen using QFDE.
Our primary conclusion is that there is a substantial LLP accumulation especially in ICL of macular and peripheral Bruch’s membrane, and a less accumulation of these particles in the periphery. Formation of a lipid wall was observed in the macular and peripheral regions of one eye, and another eye showed a similar structure forming. The results suggest that the same process is occurring in both regions, but either slower or with later onset in the periphery.
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