Laser in situ keratomileusis for different degrees of myopia.
OBJECTIVE
To determine the efficacy, predictability, stability and safety of laser in situ keratomileusis (LASIK) in treating patients with different degrees of myopia.


METHODS
We enrolled 386 eyes of 200 consecutive patients who underwent LASIK and divided them into four groups according to their degree of preoperative spherical equivalent (SE). Group 1 eyes ranged between - 1.00 and - 3.99 dioptres (D) (low myopia). Group 2 eyes ranged between - 4.00 and - 5.99 D (moderate myopia). Group 3 eyes ranged between - 6.00 and - 9.99 D (high myopia). Group 4 eyes were over - 9.99 D (extreme myopia). Follow-up was at 1 day, 1 week and 1, 3, 6, 12 and 18 months postoperatively.


RESULTS
Our study included 386 eyes of 200 patients with SE ranging from - 3.00 to - 16.00 D (mean - 7.14 +/- 2.87 D). All eyes were seen at 1 day postoperatively. A total of 360 eyes (93%) were examined at 1 week, 330 eyes (85%) at 1 month, 281 eyes (73%) at 3 months, 247 eyes (64%) at 6 months, 199 eyes (52%) at 12 months and 142 eyes (37%) at 18 months. The postoperative data from 1 day to 12 months were used because of the low follow-up rate at 18 months postoperatively. Group 1 consisted of 30 eyes. The mean SE was - 3.52 +/- 0.43 D preoperatively and - 0.40 +/- 0.58 D at 1 month, - 0.46 +/- 0.60 D at 6 months and - 0.42 +/- 0.50 D at 12 months postoperatively. Uncorrected visual acuity (UCVA) was 20/40 or better in 95% of eyes at 1 day and in 100% of eyes at 6 and 12 months postoperatively. Group 2 consisted of 151 eyes. The mean SE was - 5.36 +/- 0.67 D preoperatively and - 0.54 +/- 0.78 D at 1 month, - 0.56 +/- 0.90 D at 6 months and - 0.55 +/- 0.82 D at 12 months postoperatively. Uncorrected VA was 20/40 or better in 95% of eyes at 1 day and in 100% of eyes at 6 and 12 months postoperatively. Group 3 consisted of 167 eyes. The mean SE was - 8.15 +/- 0.94 D preoperatively and - 0.58 +/- 0.90 D at 1 month, - 0.67 +/- 1.00 D at 6 months and - 0.64 +/- 0.95 D at 12 months postoperatively. Uncorrected VA was 20/40 or better in 90% of eyes at 1 day and in 98% of eyes at 6 and 12 months postoperatively. Group 4 consisted of 38 eyes. The mean SE was - 11.09 +/- 1.10 D preoperatively and - 1.25 +/- 1.20 D at 1 month, - 1.13 +/- 1.30 D at 6 months and - 1.20 +/- 1.25 D at 12 months postoperatively. Uncorrected VA was 20/40 or better in 78% of eyes at 1 day, in 94% at 6 months and in 90% at 12 months postoperatively. Intraoperative complications (free cap) occurred in two eyes and postoperative complications were observed in three eyes, making the total complications rate 1.29% (5/386). Seven eyes lost one Snellen line of BCVA, five lost two lines and two lost more than two lines (total: 3.64%, 14/386).


CONCLUSIONS
In conclusion, LASIK is effective, predictable and safe for correcting myopia but is more accurate for correcting myopia up to -10.00 D. With more improvement in algorithms and ablation profile, we believe that LASIK can offer better results for higher myopia.
Lin
Jane-Ming
JM
Department of Ophthalmology, China Medical University Hospital, No. 2 Yuh-Der Road, Taichung 404, Taiwan.
Tsai
Yi-Yu
YY
D000328:Adult; D003319:Corneal Stroma / Q000601:surgery*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007431:Intraoperative Complications; D020731:Keratomileusis, Laser In Situ / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009216:Myopia / Q000145:classification / Q000601:surgery*; D011183:Postoperative Complications; D012449:Safety; D013524:Surgical Flaps; D016896:Treatment Outcome; D014792:Visual Acuity