Accuracy and precision of the Amadeus microkeratome in producing LASIK flaps

Purpose: To evaluate the accuracy and precision of corneal flap thickness following laser in situ keratomileusis (LASIK) performed using the 140-, 160-, and 180-mum heads for the Amadeus microkeratome (AMO, Irvine, CA). Setting: The study took place at the Cullen Eye Institute, Baylor College of Medicine, Houston. Methods: In this prospective study, using the Amadeus microkeratome, LASIK flaps were cut in 51 right eyes and 50 left eyes with the 140-mum head, 25 right eyes and 25 left eyes with the 160-mum head, and five right eyes and one left eye with the 180-mum head. The same microkeratome blade was used for bilateral cases with the right eyes always undergoing surgery first. Eyes were grouped by order of blade use for statistical analysis. The effect of preoperative corneal thickness, keratometry values, blade oscillation and translation speeds, and blade reuse on flap thickness was evaluated. Results: Mean flap thicknesses were 153 +/- 18 mum (range 97-187 mum) OD and 134 +/- 25 mum (range 79-174 mum) OS for the 140-mum head; 182 +/- 26 mum (range 105-220 mum) OD and 163 +/- 29 mum (range 105-216 mum) OS for the 160-mum head; and 235 +/- 24 mum (range 198-258 mum) for the 180-mum head. Flap thickness was significantly thicker for the first eyes cut (right eyes) and was positively correlated with increasing corneal thickness in both eyes. For the first eyes cut, flap thickness was also significantly thicker than the labeled thickness specified by the manufacturer. Conclusions: With the Amadeus microkeratome, LASIK flap thickness correlated with central corneal thickness for the 140-mum head. Reuse of the microkeratome blades produced significantly thinner LASIK flaps on second eyes cut.