Abstract
Purpose: :
Structural analysis of ex-vivo primate lenses suggests that the interfacing of non-uniform fiber ends at the star sutures is the underlying anatomical basis for the mechanism of accommodation. Modeling of the lens has provided more information about the dynamic lens changes that occur during growth and accommodation to corroborate these observations. To further support our model, we are correlating the changes in anterior star sutures during dynamic accommodation using the slit lamp to the accommodative response.
Methods: :
Normal subjects, ranging in age from 23 to 55 (n=12), were photographed using a Haag-Streit slit-lamp (16x magnification) with particular emphasis on individual lens anterior star suture branches. Photographs of the nasal half of the lens were obtained in a dilated eye in both the dysaccommodated and accommodated states (using minus lenses). In addition, the objective accommodative response to each stimulus was measured using a autorefractor (Grand Seiko WAM5500). ImageJ (NIH) was used to analyze the area of the dark band sutures. The accommodative response was correlated to the percent change in area of the dark band as compared to the dysaccommodated state (Systat v11).
Results: :
In all states, a suture branch was seen as a dark band bracketed by a pair of broader diffuse bands. The dark band area decreased in response to the accommodating stimulus. There was a trend towards a greater decrease in the area of the dark band with increasing accommodative response (Spearman, r = -0.383, p = 0.001).
Conclusions: :
The dark band of the suture branches indicates an area of minimal scatter, possibly caused by the end-to-end arrangement (non-overlapping) of fiber cells at the sutures in the dysaccommodated state. As fiber ends actively interface (overlap), there is a decrease in the area of this band that correlates with the amount of accommodative response.
Keywords: accommodation • imaging/image analysis: clinical