Corneal lenticule harvest using a microkeratome and an artificial anterior chamber system at high intrachamber pressure.

PURPOSE: To evaluate the safety and accuracy of a manual microkeratome and an artificial anterior chamber used at high intrachamber pressure to harvest corneal lenticules for lamellar keratoplasty.

SETTING: Department of Ophthalmology, University of California, Irvine, California, USA.

METHODS: Forty-seven human eye-bank corneoscleral rims were mounted on an artificial anterior chamber. A manual microkeratome was used to perform lamellar keratectomy at a mean intrachamber pressure of 95.8 mm hg +/- 4.8 (sd). Two thicknesses (300 microm and 360 microm microkeratome heads) and diameters (8.0 mm and 9.0 mm) were attempted, and the resultant lenticules were analyzed by pachymetry and digital photography.

RESULTS: In the 9.0 mm/360 microm group, corneal perforation occurred in 12 of 17 lenticules (71.2%). Except for this group, 24 of 30 corneas (80.0%) showed a less than 0.5 mm deviation from the expected diameter. Neither the horizontal nor the vertical diameter differences were statistically significant (P >.05). The difference between the horizontal and vertical diameters was within +/-0.2 mm in 23 corneas (76.7%). Three (10.0%) corneal beds contained a slightly uneven keratectomy margin.

CONCLUSIONS: This system provided accurate and smooth lenticules for lamellar keratoplasty. The precision and accuracy of the obtained corneal lenticules were better than those in previous reports. However, the 9.0 mm diameter/360 microm thickness head with high intrachamber pressure should not be applied in the clinical setting without further testing. In this laboratory study, a minimal corneal thickness of 588 microm was required to avoid perforation.