THE INTERRELATIONSHIP OF LENS ANATOMY AND OPTICAL-QUALITY .1. NONPRIMATE LENSES

We have quantified the influence of 'Y' sutures on lens optical qualit y (spherical aberration, i.e. focal length variability) as a function of age. Young (n = 6) and old (group 1, n = 5; and group 2, n = 4) bov ine lenses were initially scanned by a low-power (2 mW) helium-neon la ser beam passed either through or at a series of acute angles to sutur e branches. In all lenses, focal length variability was least when the beam was passed through areas of the lens devoid of sutures and great est when passed through sutures. In older lenses, variability was also significantly increased in all locations though to a greater degree a t sutures. Correlative morphological analysis by scanning electron mic roscopic (SEM) and three dimensional (3-D) computer-assisted drawings (CADs) revealed the following: (1) young lenses had uniformly hexagona l fibers arranged in parallel radial cell columns (RCCs), while old le nses had nonuniformly hexagonal fibers arranged in variably parallel R CCs; (2) the irregularly-sized and -shaped ends of young fibers overla pped within growth shells to form complementary anterior and posterior symmetrical 'Y' suture patterns, while larger and more irregularly-sh aped ends of older lenses overlapped to form asymmetrical 'Y' patterns ; and (3) the identical suture patterns in successive shells of young lenses resulted in inverted triangular suture planes extending from th e embryonic nucleus to the lens periphery, while the progressively wid er and more serpentine suture branches of old lenses resulted in inver ted pyramidal suture planes with narrow apices oriented towards the em bryonic nucleus and broad irregular bases oriented toward the lens per iphery. Thus, there is a significant interrelationship between lens op tical quality and structure that varies as a function of age. These re sults extend and confirm the results of our earlier studies on lenses with simpler 'line' sutures and preface our studies of primate lenses with more complex 'star' sutures. All of these studies show that lens sutural anatomy should be considered when evaluating the optical quali ty of normal and pathological lenses.