LASER IN-SITU KERATOMILEUSIS FOR MODERATE AND HIGH MYOPIA AND MYOPIC ASTIGMATISM

Objective: This study evaluated the predictability, stability, and saf ety of laser in situ keratomileusis (LASIK) in myopia and myopic astig matism. Design: The study design was a prospective, unmasked, nonrando mized clinical trial. Participants: Participating were 25 patients wit h myopia (37 eyes) with astigmatism of less than 1.00 diopter (D), div ided into 3 subgroups (-5.00 to -9.90 D, 8 eyes; -10.00 to -14.90 D, 1 0 eyes; -15.00 to -29.00 D, 19 eyes), and 37 patients with myopia (56 eyes) with corneal astigmatism of 1.00 to 4.50 D, divided into 3 subgr oups (-5.00 to -9.90 D, 12 eyes; -10.00 to -14.90 D, 24 eyes; -15.00 t o -29.00 D, 20 eyes). Intervention: LASIK was performed using the Auto matic Corneal Shaper and the Keracor 116 excimer laser. Main Outcome M easures: Visual acuity, manifest refraction, central corneal islands, ablation decentration, and patient satisfaction were measured. Results : At 12 months, predictability, regression between 1 and 12 months, un corrected visual acuity (UCVA), loss of two or more lines of corrected visual acuity, and patient satisfaction of the spherical (toric) grou ps are reported. Subgroups -5.00 to -9.90 D: 100% (75%) +/-1.00 D; reg ression less than or equal to 1.00 D in 100% (91.7%); UCVA greater tha n or equal to 20/40 in 87.5% (70%); none lost two or more lines; 100% (84%) highly satisfied. Subgroups -10.00 to -14.90 D: 60% (78.3%) +/-1 .00 D; regression less than or equal to 1.00 D in 100% (87%); UCVA gre ater than or equal to 20/40 in 77.8% (86.4%); 10% (4.3%) lost two line s; 90% (91%) highly satisfied. Subgroups -15.00 to -29.00 D: 38.9% (21 .4%) +/-1.00 D; regression less than or equal to 1.00 D in 72.2% (64.3 %); UCVA greater than or equal to 20/40 in 33.3% (40%); 5.6% (7.1%) lo st two lines; 78% (50%) highly satisfied. Differences of predictabilit y and change of manifest refraction between subgroups of -5.00 to -9.9 0 D and -15.00 to -29.00 D were statistically significant. Central isl ands (decentrations) were observed in 17% (5.6%) of eyes of the spheri cal and in 16% (4.1%) of the toric group. Overall, the corneal interfa ce was visible in 8.2%. Conclusions: The LASIK method used in this stu dy showed stability of manifest refraction and adequate uncorrected ce ntral visual acuity in a large percentage of patients with myopia up t o -15.00 D. Corneal stability was not as uniform. Central corneal isla nds were observed in a sizable minority of patients despite pretreatme nt. For myopia greater than 15.00 D, accuracy and patient satisfaction were sufficiently poor to advise against using the authors' treatment technique in these groups. Visually significant microkeratome and las er-related problems were noted in a smaller percentage of patients. Pa tients with astigmatism correction were less pleased with results than were patients who received spherical corrections.