An independent evaluation of second generation suction microkeratomes.
BACKGROUND
Microkeratome designs for lamellar refractive surgery have changed significantly in recent years. Three microkeratome systems (Automatic Corneal Shaper (Steinway Instrument Company, Inc, San Diego, Calif), Draeger Lamellar Keratome (Storz Instrument GmbH, Heidelberg, Germany), and Microprecision test model (Microprecision Instrument Company, Inc, Phoenix, Ariz) were subjected to a concurrent and independent evaluation.


METHODS
Three types of keratectomies (primary superficial stromal, secondary intrastromal, and primary deep stromal) were performed under identical conditions in human cadaver eyes. The resected discs and the beds were observed for uniformity, accuracy, centering, and smoothness. Scanning electron microscopy of the corneal beds and cutting blades was done.


RESULTS
The three systems produced irregular surfaces with chatter lines that appeared least rough with the Draeger rotating machine. The average primary and secondary section diameters were undersized by 10% in all three systems. The average primary keratectomy thickness was more accurate with Steinway, but the variability was over 20 microns in all three systems. Regarding the average secondary keratectomy thickness, Steinway tended to cut thicker, whereas Draeger and Microprecision tended to cut thinner than attempted. The Draeger blade presented the smoothest edge.


CONCLUSIONS
All three systems need substantial improvements to produce more accurate, reproducible, and smooth resections. More reliable methods to accurately measure the thickness of the resected cornea should be developed.
Hofmann
R F
RF
Department of Ophthalmology, Emory University School of Medicine, Atlanta, Ga.
Bechara
S J
SJ
D003315:Cornea / Q000601:surgery* / Q000648:ultrastructure; D016039:Corneal Transplantation; D005069:Evaluation Studies as Topic; D006801:Humans; D008855:Microscopy, Electron, Scanning; D009885:Ophthalmology / Q000295:instrumentation*; D054140:Refractive Surgical Procedures; D015203:Reproducibility of Results