Microkeratome offers excellent flap predictability, safety

Los Angeles-The BD K-3000 (BD Ophthalmics) is an easy-to-use microkeratome that surgeons can rely on for safe and predictable performance in LASIK flap creation, said Jonathan M. Davidorf, MD.

For each of the four head subgroups and with the eyes further stratified for each head with respect to order of operation, the analyses of flap thickness showed standard deviations for the means were consistently between 12 and 20 µm.

"That feature is particularly important when I am performing large zone treatments and want to be sure that I can reliably create a thin flap," Dr. Davidorf said.

Flap thickness was calculated using the subtraction technique based on intraoperative measurements of corneal thickness and stromal bed thickness obtained using an ultrasound pachymeter (Sonogauge) centered at the entrance pupil.

For the two 130-µm heads, mean ±SD flap thickness values for first eyes were 148 ±14 µm and 111 ±13 µm, respectively. For the 160-µm heads in first eyes, the mean ±SD flap thicknesses were 130 ±16 µm and 133 ±20 µm, respectively.

For all heads, mean values were consistently lower in the second eye cases. Results for the 130-µm heads were 137 ±15 µm and 93 ±12 µm; mean thickness values for the 160-µm heads were 126 ±15 µm and 110 ±18 µm, respectively.

Correlation testing confirmed that eye order was one of the strongest predictors of flap thickness (correlation coefficient = -0.34).

Flap thickness also correlated well with corneal thickness (correlation coefficient = 0.36) such that thicker flaps were achieved in thicker corneas.

Corneal curvature and microkeratome ring size were found to have minimal predictive value.

A safe procedure Safety was excellent in the series of studied eyes. There were no buttonholes, no incomplete flaps, no irregular flaps, and no eyes with epithelial defects >2 mm. A single free flap (0.8%) was encountered in the second eye of a patient with low myopia, but the patient had a good visual outcome with no loss of best spectacle-corrected visual acuity and uncorrected visual acuity of 20/20.

"Certain microkeratomes seem to have their own unique set of complications," Dr. Davidorf said. "For example, I have never encountered any central buttonholes using the BD K-3000 as I did when I used the Hansatome, but I have had three free flaps with the BD K-3000.