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Noel Marysa Ziebarth, Vivian Maria Sueiras, Nikita Likht, Vincent Moy; Molecular Diffusion in the Human Lens Capsule Assessed using Fluorescent Recovery after Photobleaching. Invest. Ophthalmol. Vis. Sci. 2018;59(9):3484.
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The lens capsule is a semipermeable membrane that allows nutrients and antioxidants to pass through it to the lens while protecting it from harmful agents. Therefore, maintenance of overall lens biology is dependent on the permeability of the lens capsule. The purpose of the current study was to determine if lens capsule permeability to multivalent metal carriers changes with age.
18 whole lenses from 9 human cadavers (age: 20-65 years) were retrieved from the Florida Lions Eye Bank. When the technicians harvested donor corneas suitable for transplantation, they also removed the lenses for use for this project. The human lenses arrived from the eye bank in sealed vials filled with Dulbecco’s modified eagle medium (DMEM). The whole lenses were stored in the refrigerator at 4○C before they were used. All lenses were used within 10 days postmortem. Whole lenses were submerged in a 0.01% solution of either alexa fluor labeled albumin (OD lens) or fluorescein labeled transferrin (OS lens). Albumin and transferrin are carriers for multivalent metals, which have been shown to induce oxidative damage to the lens through the Fenton reaction. The samples were soaked in solution overnight, allowing the molecules to diffuse into the capsule and to reach chemical and diffusional equilibrium. The lenses were then removed from the bath and placed anterior side down on a glass bottom Petri dish. Hydration was maintained during the experiments with DMEM. Fluorescence recovery after photobleaching (FRAP) experiments using a Nikon A1R confocal microscope were conducted to quantify diffusion within the lens capsule. The experiments were repeated in multiple areas within 10µm of the central depth along the z-axis of the capsule. The Nikon NIS-Elements software was used to determine the time to half maximum recovery for each measurement.
The time to recovery ranged from 9.0 to 26.9s for albumin and from 11.1 to 22.9s for transferrin. There was a trend towards decreasing time to recovery with age for albumin, meaning that albumin diffuses more quickly through the capsule in older lenses. The trend was opposite for transferrin, meaning that diffusion is slower in older lenses.
Preliminary results indicate that lens capsule permeability to multivalent metal carriers changes with age. Further research is needed to see how these changes could impact the overall biology of the lens.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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