| Abstract |
The purpose of the present study is to evaluate the 5th harmonic of Nd: YAG laser (CustomVis, Pulsar Z1 Laser System, 213 nm) in refractive surgery.
Methods
Experimental study: Forty pigmented rabbits (80 eyes) underwent myopic PRK. Photoablation was randomly assigned, with a solid state laser (SSL) used in one eye and an excimer laser (EL) in the fellow eye. Corneal tissue was preserved for scan microscopy, light microscopy and transmission electron microscopy up to one year follow-up.
Clinical study: 74 patients (146 eyes) had PRK-MMC and 18 patients (35 eyes) had LASIK for the correction of myopic astigmatism using solid state laser 213 nm (study group).
184 patients (342 eyes) had PRK-MMC and 44 patients (84 eyes) had LASIK for the correction of myopic astigmatism using excimer laser 193 nm (control group).
Refractive and visual outcomes and confocal microscope images were evaluated up to one year postoperatively.
Results
Experimental study: Immediately after the ablation, samples of both groups (SSL and EL) demonstrated smooth ablation surface covered by pseudomembrane. Activated keratocytes were observed in the upper part of the stroma in SSL and EL eyes at one and three month’s follow-up examination. Twelve months after laser ablation, epithelium, stroma, descemet membrane and endothelium in all samples did not demonstrate significant morphologic differences with the intact tissues.
Clinical study: 86% of PRK-MMC treated eyes using SSL had UVA 20/25 or better, while 56% of eyes had 20/20 or better. 3% of eyes lost more than one BSCVA Snellen line one year postoperatively. Defocus reduced from 4.70΄&λε΄&λε 2.09 D to 0.83 ΄&λε 0.55 D (29% of eyes defocus ΄&λτ 0.50 D / 60% of eyes defocus ΄&λτ 1.00 D). 73% of LASIK treated eyes using SSL had UVA 20/25 or better, while 27% of eyes had 20/20 or better. No eyes lost more than one BSCVA Snellen line one year postoperatively. Defocus reduced from 5.86 ΄&λε 1.36 D to 0.93 ΄&λε 0.77 D (45% of eyes defocous΄&λτ 0.50 D / 64% of eyes defocus ΄&λτ 1.00 D).
93% of PRK-MMC treated eyes using EL had UVA 20/25 or better, while 76% of eyes had 20/20 or better. No eyes lost more than one BSCVA Snellen line one 11
year postoperatively. Defocus reduced from 5.03 ΄&λε 2.29 D to 0.72 ΄&λε 0.42 D (37% of eyes defocus ΄&λτ 0.50 D / 73% of eyes defocus ΄&λτ 1.00 D). 71% of LASIK treated eyes using EL had UVA 20/25 or better, while 47% of eyes had 20/20 or better. No eyes lost more than one BSCVA Snellen line one year postoperatively. Defocus reduced from 6.74 ΄&λε 1.65D to 0.62 ΄&λε 0.48 D (41% of eyes defocous ΄&λτ 0.50 D / 88% of eyes defocus ΄&λτ 1.00 D).
One year follow-up images with confocal microscopy after refractive surgery using EL or SSL revealed regenerated subepithelial nerve plexus and normal endothelial cells in morphology and density.
Conclusions
Experimental and clinical results are similar between both groups (SSL and EL). PRL and LASIK using the Pulzar Z1 213 nm wavelength solid-state laser seem to be safe and effective procedures for the treatment of myopic astigmatism.
Future prospective studies, including more eyes in a large range of attempted corrections, are needed to draw final conclusions.
Key words: Solid state laser, Nd: YAG laser 213 nm, excimer laser, ArF 193 nm, PRK, mitomycin C, LASIK, scan microscopy, light microscopy, transmission electron microscopy, confocal microscopy
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Η χρήση του laser στερεάς κατάστασης NG:YAG laser 213nm στην διαθλαστική χειρουργική
