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Rebecca K. Zoltoski, Elizabeth Wyles, Jennifer S. Harthan, Jer R. Kuszak; Effect Of Accommodation On The Lens Ultrastructure As Measured Using Slit Lamp Photos And Wave Front Analysis. Invest. Ophthalmol. Vis. Sci. 2012;53(14):1343.
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© ARVO (1962-2015); The Authors (2016-present)
During dynamic focusing, the shape, as well as the ultra-structure of the lens is changed. Our lab is investigating these changes, specifically at the sutures of the lens during accommodation. We have hypothesized that unique structural features and organization of fiber cells enables them to interface at the sutures resulting in a change in surface curvature of the lens, increasing lens thickness, allowing near focus to occur. We are reporting preliminary data on lens slit lamp photos, OCT of lens thickness changes, and sequential ray tracing analysis of the patterns associated with the lens sutures to highlight the importance of the ultra-structure of the lens in the accommodative process.
OCT (Visante™), objective accommodative response and wavefront analysis (iTrace™), and slit lamp photos (Haag Streit, 16X magnification, dilated eye) were collected on normal subjects, between the ages of 23-63 (n=15). The data was collected on the right eye. Accommodation was stimulated using minus lenses in front of the viewing eye in 2.5 D increments up to 10 D or until the subject could no longer keep the target clear. For the photos a prism system was used to keep the eye appropriately oriented. ImageJ (NIH) was used to analyze the area of the sutural components. Data were analyzed using Systat v11 to correlate accommodative response with total HOA, SA and the foil patterns, as well as changes in slit lamp suture areas. Spearman Rank Correlation coefficients and p values are presented.
As the accommodative response increased, the thickness of the lens increased (0.13 ± 0.05 mm/D). In all states, the slit lamp photos and the aberrations demonstrated changes in the lens ultra-structure. For the photos, multiple sutures were identifiable, with each suture branch, having a clear central suture branch region bracketed by broader diffuse bands.The area of the dark band decreased with increasing accommodative response (Spearman, r = -0.495, p < 0.001). In addition, changes in the foil patterns of aberrations were observed; however, the response was not consistent across all subjects, so the results were not significantly different (trefoil: r2 = -0.282, p = 0.169, tetrafoil: r2 = -0.306, p = 0.169).
As accommodative response increased, an increase in lens thickness and changes in the ultra-structure of the lens occurred. These changes have been characterized by analyzing the dark central region of the suture patterns and the foil aberration patterns in some individuals. These changes may be caused by the end-to-end arrangement (non-overlapping) of fiber cells at the sutures in the dysaccommodated state, which actively interface (overlap), during accommodation to increase lens thickness.
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