Predictability of Donor Lamellar Graft Thickness and Diameter Using a Microkeratome in Porcine Eyes

ABSTRACT

PURPOSE: To evaluate the thickness and diameter of a lamellar graft with microkeratome and to determine its usefulness as a donor lamellar graft for microkeratome-assisted lamellar keratoplasty. METHODS: Thirty-six porcine eyes were randomly assigned to three groups according to the microkeratome (Automated Corneal Shaper(R)) depth plate group 1 (#300 micrometer plate, 13 eyes), group 2 (#400 micrometer plate, 12 eyes), and group 3 (#450 micrometer plate, 11 eyes). Free corneal buttons were made with the corneal shaper after a uniform suction duration of 10 seconds. Central corneal thicknesses were measured with an automated ultrasound pachymeter prior to the procedure. After the lamellar graft was made, the remaining corneal thickness was measured with the same method. The difference between the two values was hypothesized to be the lamellar graft thickness. In addition, the diameter of lamellar graft was measured by calipers. RESULTS: The mean lamellar graft thicknesses in groups 1, 2, and 3 were 218.2+/-26.6 micrometer (72.7%), 312.3+/-26.7 micrometer (78.1%) and 345.7+/-36.7 micrometer (76.8%), respectively. There were no significant differences between the three groups according to the results brought by the microkeratome depth plates (p=0.239). The mean lamellar graft diameters in groups 1, 2, and 3 were 8.49+/-0.28 mm, 8.43+/-0.26 mm and 8.58+/-0.28 mm, respectively. There were no significant differences between the three groups (p=0.368). No relationship was found between lamellar graft thickness and diameter (r=-0.009, p=0.480). CONCLUSIONS: These results suggest that in forming donor lamellar grafts with microkeratome plates, thicker resection depth is needed because the actual lamellar graft were shown to be thinner than the target values. However, lamellar grafting is thought to be unsuitable for lamellar keratoplasty because it results in considerable thickness variability.