Abstract
Purpose: :
To evaluate the accuracy,uniformity coherent factors of LASIK flaps created with a mechanical microkeratome MoriaII 90,110,130 head.
Methods: :
It was a case-control study. 87 patients underwent LASIK in both eyes in alternating fashion with MoriaII 90 head (52eyes,26cases), 110 head (58eyes,29cases),130 head (64eyes,32cases). One week after surgery, anterior segment optical coherence tomography was performed four times on each eye to measure flap thickness at 20 points on four meridians and the results assessed for accuracy, uniformity and coherent factors.
Results: :
The central thickness of corneal flaps was (119.23±15.65), (140.42±12.26),and (165.92±17.00)µm by MoriaII 90, 110 and 130 head respectively. The shape of the corneal flaps in the three Groups like a concave lens, the central zone was significantly thinner than the paracentral and peripheral zones (p<0.05). The central flap thicknesses were statistically significantly more accurate and regularity than the flap in the peripheral zone (F=212.419,P<0.05). The mean difference of right eye(19.58±0.44µm) was higher than left eye(16.55±0.44µm);The mean difference of knife in-side(21.30±0.55)µm was higher than the knife out-side(14.36±0.64)µm(F=25.341,44.461;P<0.05).
Conclusions: :
The central flap thicknesses were accurate compared with the expected value. The mean flap thickness in the three Groups were not uniform:The thicker of corneal flaps was expected,the greater deviation would be. The difference order of the surgery made the difference thickness of corneal flap between right eyes and left eyes , between the into side of the knife blade and the out side of the knife blade. The flap thickness of right eyes were thicker than left eyes according to the surgical order between two eyes. We also find that the flap thickness of blade in-side were thicker than that of out-side.
Keywords: anterior segment • cornea: epithelium • clinical (human) or epidemiologic studies: treatment/prevention assessment/controlled clinical trials