LASER IN-SITU KERATOMILEUSIS FOR LOW MYOPIA AND ASTIGMATISM WITH A SCANNING SPOT EXCIMER-LASER

PURPOSE: To determine the efficacy, predictability, safety, and short term stability of laser in situ keratomileusis (LASIK) in treating pat ients with low myopia and astigmatism using the Chiron Technolas Kerac or 117 PlanoScan excimer laser. METHODS: We retrospectively studied th e results of our initial 83 eyes with myopia ranging from -1.13 to -7. 25 diopters (D)and astigmatism of no more than 4.00 D that underwent L ASIK with the Chiron Technolas Keracor 117 PlanoScan. Follow-up was at 1 day, 1 month, and 3 to 6 months. RESULTS: Mean baseline spherical e quivalent refraction was -3.54 +/- 1.41 D and cylinder -1.64 +/- 1.14 D, Mean postoperative spherical equivalent refraction was -0.52 +/- 0. 50 D at 1 month and 0.65 +/- 0.62 D at 3 to 6 months; mean postoperati ve refractive cylinder was -0.45 +/- 0.54 D at 1 month and -0.50 +/- 0 .63 D at 3 to 6 months. Fifty-three percent (44 eyes) achieved a spher ical equivalent refraction within +/- 0.50 D and 81% (67 eyes) within +/- 1.00 D of emmetropia at the last examination, Fifty-seven percent (47 eyes) achieved a refractive cylinder of less than or equal to 0.50 D, and 27% (22 eyes) had an undercorrection of their refractive cylin der at the last examination. An uncorrected visual acuity of 20/40 or better was achieved in 86% (71 eyes) of patients on postoperative day one, in 81% (67 eyes) at 1 month, and in 76% (63 eyes) at 3 to 6 month s. Twenty-eight percent (23 eyes) saw 20/20 or better uncorrected at t he last visit (41% [34 eyes] had a baseline spectacle-corrected visual acuity of 20/20). There was no statistically significant difference i n the refractions or uncorrected visual acuities between the different postoperative examinations. No eye experienced a loss of spectacle-co rrected visual acuity of more than one line at the last examination. C ONCLUSION: LASIK with the Chiron PlanoScan excimer laser appears to be an effective, safe, and reasonably predictable means to reduce low my opia and astigmatism, Adjustment of computer algorithms is needed to d ecrease the number of undercorrection.