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N. S. Tsiklis, G. Kymionis, G. Kounis, V. Diakonis, S. Charisis, S. Yoo, I. Naoumidi, I. Pallikaris; Photorefractive Keratectomy Using Ultraviolet Solid State Laser 213 Nm and Excimer Laser 193 Nm: A Randomized Comparative Experimental Study. Invest. Ophthalmol. Vis. Sci. 2007;48(13):5333.
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© ARVO (1962-2015); The Authors (2016-present)
To compare the histopathologic changes after myopic PRK with solid state laser (213 nm wavelength) and excimer laser (193 nm) in experimental model (rabbit corneas).
Forty pigmented rabbits underwent myopic PRK (6 D at 5mm optical zone with 0.5mm transitional zone) with solid state laser (213 nm wavelength) in one eye and excimer laser (193 nm) in the fellow eye (randomization with a flip of a coin). Rabbits sacrificed immediately after the ablation (n=10), at 7 days (n=10), one month (n=8), 3 months (n=6) and 6 months (n=6) after the surgery. Corneal tissue was preserved for Transmission electron microscopy (TEM) and Scan microscopy (SEM) immediately after the ablation, Light microscopy (LM) at all postoperative intervals.
Immediately after the ablation, light and scan microscopy revealed smooth ablation surface with no edema, or distortion of the adjacent corneal stroma. The structure of pseudomembrane after the ablation was the same for both lasers and viable keratocytes underneath the ablation zone indicates no thermal damage (solid state laser). All corneas were re-epithelialized within 7 days. The solid state laser speciments demonstrate thinner than normal epithelium layers (2-3 layers, less winds cells) while after excimer laser ablation normal epithelial thickness (5-6 layers) or mild hyperplasia were observed. At 1, 3 and 6 months postoperatively, there was normal appearance of all corneal layers (epithelium, stroma, Descemet’s membrane and endothelium) in both groups. Endothelial layer was intact and endothelial cells appeared normal in all samples of both groups’ at all postoperative examinations.
Photorefractive keratectomy in rabbits with ultraviolet solid state laser (213 nm wavelength) and excimer laser (193 nm wavelength) shows similar histopathologic findings.
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