Evaluation of the reliability of the Nidek MK-2000 microkeratome for laser in situ keratomileusis.

PURPOSE: To evaluate the performance of the Nidek MK-2000 microkeratome in corneal flap creation for laser in situ keratomileusis (LASIK) in Asian eyes and the simplicity of its use for the beginner. METHODS: A prospective study of 200 Asian eyes was performed. The corneal flaps were created using the Nidek MK-2000 microkeratome 130-microm and 160-microm thickness plates with 8.5- and 9.5-mm suction rings. Ease of obtaining suction was evaluated and measurements were done for flap thickness, flap diameter, hinge size, and hinge-to-center-of-pupil distance. RESULTS: Subjectively, even in small eyes, the procedure of obtaining the required suction and creating a good flap was easy and reliable with the Nidek MK-2000 microkeratome. Average flap thickness was 120.52 +/- 16.49 microm (range, 84 to 162 microm) for the 130-microm thickness plate with the 8.5-mm suction ring. Mean flap diameter was 9.16 +/- 0.43 mm, mean hinge size was 4.96 +/- 0.36 mm, and mean hinge-to-center-of-pupil distance was 4.16 +/- 0.28 mm. With the 9.5-mm suction ring, mean flap thickness was 122.06 +/- 18.54 microm (range, 84 to 149 microm), mean flap diameter was 9.85 +/- 0.35 mm, mean hinge size was 5.28 +/- 0.36 mm, and mean hinge-to-center-of-pupil distance was 4.49 +/- 0.27 mm. For the 160-microm plate with a 8.5-mm suction ring, the flap thickness was 172.71 +/- 27.49 microm (range, 121 to 203 microm), flap diameter was 9.13 + 0.37 mm, mean hinge size was 5.02 +/- 0.29 mm and mean hinge-to-center-of-pupil distance was 4.21 +/- 0.29 mm. There were no complications of corneal flap creation. CONCLUSION: The Nidek MK-2000 microkeratome was effective, safe, and reliable, even in small eyes.

Ornithine decarboxylase activity in rabbit retina following treatment with alpha-difluoromethylornithine.

The rabbit retina has been utilized as a model for the study of abnormal cellular proliferation on the retinal surface and into the vitreous, a process commonly initiated by trauma and generally leading to retinal detachment. This study characterizes the ability of alpha-difluoromethylornithine (alpha-DFMO), a suicide inactivator of L-ornithine decarboxylase (EC 4.1.1.17) to inactivate normal retinal ornithine decarboxylase (ODC) activity in the crude supernatant fraction after incubation with different concentrations of alpha-DFMO and at various times after intraocular administration. Partial inactivation of ODC activity occurred following preincubation of crude retinal supernatant fraction with 10(-5) M alpha-DFMO (N = 3; 34 +/- 6.9% of control), whereas preincubation with 10(-8) M alpha-DFMO did not alter ODC activity significantly (N = 3; 94 +/- 2% of control). Different concentrations of alpha-DFMO administered intraocularly inactivated retinal ODC activity to varying degrees with different rates of recovery. No gross toxicity occurred with ocular tissues following intravitreal administration of alpha-DFMO as determined by electrophysiologic measurements, by indirect examination of the retina, and by measurement of intraocular pressure. These results suggest that alpha-DFMO may be a useful tool in which to define the physiologic role of ODC and polyamines in intraocular cellular proliferative diseases.