Effect of varying microkeratome parameters on laser in situ keratomileusis interface surfaces

To evaluate the effect of altering microkeratome parameters (oscillation rates and head-advance speeds) and repeated blade use on human and porcine laser in situ keratomileusis interface surface quality and to evaluate correlations between human and porcine interface surface quality.

Emory Vision, Atlanta, Georgia, USA.

Corneal flaps were created in porcine eyes and human cadaver eyes with an Amadeus I microkeratome using varying head-advance speeds and oscillation rates. Microkeratome blades were used once in 18 porcine eyes, twice in 18 human eyes (simulating clinical use), and 5 times in 15 porcine eyes. The interface surface was imaged with electron microscopy, with overall bed quality and surface smoothness graded from 1 to 5 (smoothest to roughest) by 5 masked corneal specialists using the same grading criteria for porcine eyes and human eyes.

Neither oscillation rates nor head-advance speeds consistently influenced bed smoothness in any group. There were no differences in bed quality between first cuts and second cuts in human eyes or between porcine eyes with multiple blade use. Porcine eyes had statistically significantly smoother stromal beds than human eyes (P<.01); there was no correlation between porcine eye scores and human eye scores (r = -0.1).

Neither alterations in microkeratome parameters nor repeated blade use consistently influenced stromal bed quality in human or porcine eyes. No subjective correlation existed between stromal bed qualities of porcine corneas and human corneas; therefore, future studies evaluating corneal stromal bed quality should be performed in human corneas only.