ELECTRON MICROSCOPIC STUDIES OF CRYSTALLINE LENSES

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DESCRIPTION (Investigator's Abstract): The long term objective of this project is to gain a qualitative and quantitative knowledge of human lens morphology as it relates to lens function and dysfunction. Specific aims are; 1) Slit lamp biomicroscopy (direct and retro-illumination) will be used to identify opacities and specific zones of discontinuity (the anterior and posterior zones of disjunction, the anterior and posterior zones of the adult nucleus and the inner zones of the fetal nucleus) in cortical (C), mixed cortical and nuclear (CN) and nuclear (N) human cataracts. After extracapsular surgical removal, these lenses will be dissected by a method that the investigators have developed that permits that intact retrieval of these same opacities and zones of discontinuity for correlative EM analysis. Stereo SEM will then be used to characterize the gross and fine structure of the opacities and zones of discontinuity with specific reference to lens sutural anatomy.This information will be used to produce 3D CAD reconstructions of lens suture "plane" anatomy within opacities and specific zones of discontinuity. 2) A helium-neon laser scan device of the investigator's own design will be used to quantify the negative influence of lens sutural anatomy on lens focal variability (i.e. spherical aberration) in variably aged, normal non-cataractous primate (macaque) lenses. After laser analysis, these lenses will be dissected according to the investigator's method to retrieve intact sutures from the fetal and adult lens nucleus as well as from the adult lens cortex for correlative EM analysis. Stereo SEM will then be used to characterize the gross and fine structure of the sutures in these lenses as a function of development (the fetal nucleus), growth (the adult nucleus) and age (the adult cortex). These age-related zones of normal primate lens are the equivalent of respectively, and the inner zones of the fetal nucleus, the anterior and posterior zones of the adult nucleus, and the anterior and posterior zones of disjunction. This information will be used to produce 3D CAD reconstructions of lens suture "plane" anatomy as a function of lens development, growth and age. 3) Finally, stereo SEM, TEM [medium voltage and conventional] and freeze-etch analysis will be used to characterize the ultrastructure of lens sutural and nuclear anatomy in the above described lenses. Specifically, these studies will qualify and quantify the gap junctions, square array membrane and endocytosis of lens sutural and nuclear anatomy as a function of development, growth, age and pathology. The importance of these studies is derived from the following facts:1) the results of these studies will permit for the first time the qualification and quantification of structural changes in the human lens as a function of pathology that correlate with opacities and specific zones of discontinuity as observed by slit lamp biomicroscopy; 2) the results of these studies will permit the qualification and quantification of structural changes in the comparable areas of normal primate lens as a function of development, growth and age that can be correlated with a specific optical function (focal variability). Thus, by extrapolation, the results of these two sets of studies can be correlated to identify ongoing changes in human lens structure during development, growth and age that herald rather than result from lens pathology (presbyopia and cataract).