Abstract
Purpose: :
Limited information is available on how transmission of visible light changes with the age of the human crystalline lens (HCL). Therefore, a UV/Visible spectroscopic method was developed to determine light transmission characteristics of excised HCLs of various ages.
Methods: :
HCLs (2-7 days post-mortem) stored in Optisol-GS or Eusol-C media were received from eye banks and visually examined for opacity. Lenses were positioned on a printed background with the anterior surface facing up, examined under a dissection microscope and photographed. Afterwards, the HCLs were submersed in BSS®, and cross-sectional scans for opacities were performed with a non-contact high frequency (45-60 MHz) ultrasound biomicroscope at various focal planes. Only HCLs with transparent central 5-6 mm zones were used, which were then stored in phenol-red free Eusol-C. Samples were placed in a quartz cell-HCL holder assembly, which was filled with BSS. The UV/Vis transmission analysis was carried out in the wavelength range 850-300 nm using a Perkin-Elmer Lambda 35 UV/Vis spectrophotometer equipped with a Lab Sphere RSE-PE-20 integrating sphere. HCLs in age groups (yrs): 10-19 (8 HCLs from 4 donors), 20-29 (8 HCLs from 4 donors), 30-39 (8 HCLs from 4 donors) and 40-49 (12 HCLs from 6 donors) were evaluated. Composite spectra were built for each age range.
Results: :
In contrast to previous studies, efforts were made in our study to minimize artifacts during light transmission measurements of human lenses. The lenses were prescreened for opacities. They were stored and measured in appropriate physiological media, which minimizes artifacts from Fresnel reflections. In addition, the lenses were not compressed in order to minimize artifacts such as opacification and allow the light transmission characteristics of the lens to be measured in its natural state. For longer visible light wavelengths (850-600 nm), high transmittance values (~95%) were measured for all HCLs. However, with increasing age a significant reduction in light transmission was seen in the visible blue light range (500-420 nm). Cut-off wavelength (410 nm) was the same for all ages.
Conclusions: :
This study utilizes a novel method for measuring light transmission of HCLs with minimal introduction of artifacts.
Keywords: optical properties • aging