THE INTERRELATIONSHIP OF LENS ANATOMY AND OPTICAL-QUALITY .2. PRIMATELENSES

We have quantified the influence of lens sutural anatomy on optical qu ality (focal length variability, i.e. spherical aberration) in adult m onkeys (Macaque nemestrina). Adult lenses (n = 6) were initially scann ed by a low-power helium-neon laser beam that was passed at a series o f acute angles to, and/or directly through, lens sutures. Optical anal ysis showed that while the 'star' sutures of primate lenses exerted a quantifiable negative effect on focal length variability, this detrime ntal effect was far less significant than that attributable to 'line' and 'Y' sutures in non-primate lenses. Correlative morphological and 3 -D computer-assisted drawing (CAD) analysis of the laser-scanned lense s areas, as well as of variably aged lenses (n = 30), revealed that pr imates have a more complex lens architecture than non-primates. Nonpri mate lenses feature suture planes, aligned along the Visual axis that are responsible for a significant quantifiable increase in spherical a berration. Primate lenses are characterized by an absence of continuou s suture planes aligned along the visual axis. Rather, 3-D-CADs of pri mate lenses demonstrate that distinct generations of progressively mor e complex sutures are produced as a function of development, growth, a nd age. In succession, 'Y' sutures (three branches) are formed through out embryonic development,'simple star' sutures (three-six branches) e volve after birth and through infancy, 'star' sutures (six-nine branch es) are made in young adult lenses and, finally, 'complex star' suture s (nine-15 branches) are laid down from middle through old age. In vie w of the fact that slit-lamp evaluation of cataractous lenses often re veals abnormally thin zones of discontinuity, it is significant to not e that the temporal development of the zones of discontinuity in norma l human lenses is essentially identical to the progressive iteration o f offset monkey lens sutures. In conclusion, these studies describe a specific structural aspect of lenses that adversely influences optical quality, and relates it to the most commonly employed clinical techni que to identify and monitor the progress of cataracts.