Abstract
Abstract: :
Purpose: To investigate the angular light scattering properties of excised eye lenses with intact lens capsule. More specifically to study if the angular distribution changes with wavelength and total light scattering in normal and cataractous lenses. Methods: A TIS-method (Total Integrated light Scattering) is used to estimate the light scattering properties. The lens, surrounded by biological salt solution, is positioned in a lens holding (LH) unit. Light from one of five laser-lines (458, 488, 514, 543 and 633 nm) is fed into an optical fiber whose other end is connected to the bottom of the LH unit. The lens, positioned at focal length distance from the fiber-end, collimates the laser light. The light is collected by an integrating sphere, and by using an extra circular port, the directly transmitted light (collimated light) can be separated from the scattered light. The angular distribution is then measured by using a computer controlled adjustable diaphragm to vary the sphere's angle of acceptance. Results: We measured 9 lenses from 7 donors (51 to 85 yrs). The lenses had a total light scattering range of about 19 to 87%, and a transmission range of about 86 to 94% @ 633 nm. The angular intensity distribution is plotted vs angle in a range of about 1° and 10° (half angle). Data is analyzed with power function (a*x^b) curve fitting, and with Half-Width-Half-Max (HWHM) measures. We found no significant dependency between angular distribution and wavelength. However, when compared to the total light scattering a significant shift towards lower values is found in the power function exponent, b, for lenses with pronounced light scattering. Conclusion: The results indicate that this method is useful in studies to determine light scattering properties of excised eye lenses. In a fairly simple way, dependence of wavelength and angular distribution in normal and cataractous lenses can be investigated.
Keywords: 519 physiological optics • 338 cataract • 309 aging