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Satish Herekar, Marc D Friedman, David Muller, Harald P Studer, Anastasios J Kanellopoulos; Photochemical Intra-Stromal Cross-linking for Presbyopia and Hyperopia. Invest. Ophthalmol. Vis. Sci. 2014;55(13):1552.
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To determine the effects of using patterned UVA light during photo-chemical cross-linking as a means of inducing corneal multi-focality for Hyperopic and Presbyopic corrections.
Patient specific FEA modeling (Optimeyes, ISS, CH, using full 3D model of cornea, limbus and scleral ring of 4mm width ~50’000 first order brick elements per model, 5 layers of elements over thickness, IOP=15mmHg, with pre-stressing assuming bulk cross-linking over an annulus 5.0mm to 8.5mm diameter and 250ums depth and 400ums depth at 2.5 times stiffening) was undertaken to predict curvature and wavefront change results. Fresh whole porcine eyes were obtained <24 hours postmortem in saline on ice from Sioux-preme (Sioux City, IA). Eyes were brought to 37oC in a humidity chamber, epithelium was removed with a dull blade, and intraocular pressure of 15mmHg was applied using a water column. 0.1% Rf in 0.85% saline drops were applied in the humidity chamber for 20 minutes. Eyes were scanned (Pentacam HR) then placed under a programmable UVA pattern projector (KXL II) and irradiated at 30mW/cm2 while pulsing 1 sec ON and 1 sec OFF with dual annuli (2mm-4mm and 5.5mm to 7.5mm) for a total UVA dose of 22 minutes (20J/cm2). The eyes were then scanned (Pentacam HR) once again to obtain curvature, densitometry, and wavefront changes. Two hyperopic patients (Athens Gr) were treated (by AJK, de-epithelialized and 0.1% riboflavin soaked first) with 7.2J/cm2 and 12J/cm2 30mW/cm2 patterned with single annulus 6mm to 9mm, 1 sec ON, 1 sec OFF and topography pre and post scans were obtained.
FEA curvature and wavefront analysis showed an increase in central corneal curvature and spherical aberration. Topographies/densitometries of pig eyes showed para-central steepening and peripheral flattening. Both patients showed central steepening.
FEA, ex-vivo pig eyes and patient outcomes indicated induction of corneal multi-focal changes in a dose dependent manner towards correction of hyperopia and presbyopia due to photo-chemical intra-stromal cross-linking.
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