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Elizabeth A. Knighton, Rebecca K. Zoltoski, Daniel K. Roberts, Jacob T. Wilensky, Jer R. Kuszak; Rate of Increase in Lens Thickness Decreases With Age. Invest. Ophthalmol. Vis. Sci. 2011;52(14):1540.
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We create dynamic computer models to recreate anatomical relationships at the fiber level in the lens during growth and accommodation. To do this accurately, in addition to studying the lens ultrastructure, gross lens dimensions are necessary to increase the accuracy of the model. As we age, it is expected that the rate of growth will decrease, especially after the age of 50.
A-scan ultrasounds (PalmScanTM AP2000 or Accutone) were collected on 305 subjects between the ages of 22 and 93. The younger subjects were looking at a non-accommodating distance target using minus lenses to fully relax their accommodation. The older subjects were asked to fixate at distance. Linear regression (Systat v11) of age and LT (mm) of the right eye was used to assess the increase in LT (± SEM) across age (µm/year).
During the ages assessed, the accommodative ability of the lens is decreasing, while lens growth continues. An increase in LT of 30 ± 1 µm/year was noted across the seven decades of life measured. To assess the differences in growth across age, the data was first divided into two age groups (50, n=223). Below the age of 50, the LT increased 59 ± 5 µm/year (LT = 0.059 (±0.005) * age + 1.902 (± 0.157), R = 0.532, p < 0.001). While above the age of 50, the increase per year dramatically dropped to 14 ± 3 µm/year (LT = 0.014 (±0.003) * age + 4.014 (±0.202), R = 0.297, p < 0.001). In younger subjects, the increase in LT was much greater than the reported values of 13 - 29 µm/year between the ages of 20 and 60 using various methods.
The rate of lens growth may be faster in younger subjects than once thought, but that in a short span of time, the rate slows dramatically. Unfortunately, this type of analysis does not provide information on the influence of the addition of fibers and compaction to the lens dimensions. Further analysis of more lenses, particularly in the earlier decades of life, as well as using other techniques, is warranted to provide accurate growth rate assessment for lens aging.
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