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Predictability of donor lamellar graft diameter and thickness in an artificial anterior chamber system
Clark L Springs1, Mark A Joseph, J Vernon Odom
1Cornea, External Diseases, and Refractive Surgery Service, West Virginia University Eye Institute, Morgantown 26506, USA. csprings@hsc.wvu.edu
Purpose:
To identify factors affecting the predictability and report results of donor lamellar graft diameter and thickness in an artificial anterior chamber obtained with a microkeratome.
Methods:
Lamellar lenticules were obtained from 25 human corneoscleral rims mounted in an artificial anterior chamber. Lenticules measuring 9 mm were attempted at two thicknesses (250 microm and 350 microm heads). Intrachamber pressure of 65 mm Hg was confirmed with Barraquer tonometry. Keratometry, pachymetry, limbal white-to-white, and qualitative mires with the diameter applanation lens were evaluated as possible factors predictive of lenticule diameter and thickness. Diameters and thicknesses were measured with calipers and pachymetry, respectively. RESULTS Ninety-two percent (23/25 lenticules; 14/15 in 250 microm, 9/10 in 350 microm) were +/- 0.25 mm of the intended diameter and 76% (19/25 lenticules; 12/15 in 250 microm, 7/10 in 350 microm) were within +/- 100 microm of the intended thickness. Ovoid applanation mires with the diameter applanation lens represented tissue herniation within the artificial anterior chamber and led to ovoid lenticules (2/25).
Conclusions:
Lenticules of 9 mm +/-0.25mm in diameter were highly reproducible with proper corneoscleral rim seating. Intrachamber pressure confirmed with Barraquer tonometry is important in obtaining lenticules of consistent diameter and adequate thickness. Ovoid applanation mires may herald improper corneoscleral rim seating and result in a similarly shaped lenticule. A 2 mm or greater corneoscleral rim is recommended to prevent tissue herniation within the artificial anterior chamber used in this study.