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Vivian M Sueiras, Vincent T Moy, Noel Marysa Ziebarth; Transport and Structure Modifications of the Human Lens Capsule with Age. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):5580.
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© ARVO (1962-2015); The Authors (2016-present)
To determine how transport through the human lens capsule changes with age and how these changes are correlated to the structure.
Transport: Fluorescence recovery after photobleaching (FRAP) experiments were conducted on the lens capsule from 4 human cadavers (age: 60-90 years). The anterior lens capsule was separated from the lens using the continuous curvilinear capsulorhexis technique. Each excised capsule was submerged in a 0.01% solution of anionic, fluorescein-labeled dextran in PBS (40kD MW). The samples were soaked overnight, allowing the molecules to diffuse into the capsule and to reach chemical and diffusional equilibrium. The capsules were then removed from the bath, washed 3 times with PBS, plated on a glass bottom dish and hydrated with PBS. A Nikon A1R confocal microscope was used to conduct FRAP experiments. The argon laser was used to bleach out a circle of radius 10µm at a plane within the capsule, creating a region of interest (ROI). Changes in fluorescence intensity stemming from the diffusion of the fluorescent tracer were monitored over time for 60 seconds. This data was normalized using an “unbleached” region away from the ROI. The time to half recovery was determined for each sample.<br /> <br /> Structure: Atomic Force Microscopy (AFM) was used to image the structure of the outer surface of the anterior lens capsule of 6 human cadavers (age: 44-88 years). Prior to imaging, the whole lens was stabilized by embedding the posterior portion of the intact lens in a 5% agarose gel. The surface was submerged in Dulbecco’s Modified Eagle Medium. Images were obtained in contact mode using an Asylum MFP-3D AFM. The topographical images obtained with the AFM were flattened (order 1) and filtered (median 3x1) prior to analysis with the Asylum AR software. Interfibrillar spacing and fiber diameter were calculated from the images.
The time to half maximum recovery ranged from 2.77 to 3.10s. With age, the recovery time was significantly slower (p=0.026), indicating that transport was impeded in older lenses. Interfibrillar spacing was 0.76-1.48µm and fiber diameter was 120-484nm. Both parameters decreased with age, although the decrease was not statistically significant.
With age, interfibrillar spacing decreases, which could contribute to the impedance of transport found in older lenses. Therefore, structural modifications to the lens capsule with age are correlated to transport.
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