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Falk Schroedl, Andrea Trost, Barbara Bogner, Christian Runge, Clemens Strohmaier, Guenther Grabner, Herbert A. Reitsamer; A New 355nm UV Laser For Corneal Surgery: First Results In An Acute Animal Model. Invest. Ophthalmol. Vis. Sci. 2012;53(14):1509.
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© ARVO (1962-2015); The Authors (2016-present)
To test for molecular-biological and morphological alterations in the eye due to the use of a 355nm UV-laser in an acute rabbit model.
Corneal flaps (depth 170 µm to 270 µm; flaps kept in place) were created with a new UV nanosecond laser (Schwind SmartTech; wavelength 355nm; pulse frequency 150 kHz; pulse duration 0.5-1.0ns; pulse energy 2.2µJ; 7J/cm2 total dose; spot spacing 6x6 µm; side cut Δz 1µm) in anesthetized rabbits (local and general anesthesia; chinchilla bastards, n=10; meeting the ARVO regulations). Right eyes received treatment, left eyes served as controls. Animals were kept in controlled deep anesthesia and sacrificed 4hrs post treatment. Aqueous humor was screened for IL-6 and TNF-α via ELISA. Corneas were prepared for TUNEL-assay, standard histology and electron microscopy. Ultrastructural analysis of the lens-capsule and histology of the retina was performed.
In the aqueous humor, IL-6 was slightly elevated in 2/10 eyes (1,19/ 0,76 pg/ml; detection limit 0,03 pg/ml) 4 hrs post treatment, whereas TNF-α was slightly elevated in 3/10 eyes (2,2/ 2,39/ 2,9 pg/ml; detection limit 0,13 pg/ml); in two of these animals also the left untreated eye showed elevated TNF-α levels (1,91/ 2,01 pg/ml). Eyes with elevated IL-6 were not matching those with TNF-α. Standard histology revealed no tissue alteration. The horizontal cut was not detectable, while the vertical cut was detectable in 5/10 eyes. A TUNEL-positive signal was seen only in cell layers closely adjacent to the vertical cutting edge. Ultrastructural analysis of the cornea revealed regular cell borders in all layers with intact membranes/ cell-cell-contacts and absence of chromatin condensation/ apoptotic bodies. The lens epithelium showed intact cell borders and membranes; a vacuolization was detected in both treated and untreated eyes, possibly representing a species difference. Screening of retinal semithin-sections revealed regular morphology in treated vs. control tissue.
This new UV-laser showed no serious morphological tissue alterations 4 hrs post treatment at the histological and ultrastructural level. Slightly elevated IL-6 and TNF-α levels were both detected in different eyes. Further, these parameters are several factors lower compared to e.g., YAG-iridotomy (measured after 24 hrs), therefore an inflammatory reaction can be denied. This new 355nm laser most likely represents a useful tool for future corneal surgery, awaiting its pass in a chronic test environment.
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