[Twilight visual acuity after correction of myopia with LASIK].
BACKGROUND
Data on mesopic vision after LASIK are not available to date. We therefore evaluated mesopic vision in myopic eyes before and after LASIK.


METHODS
Sixty-seven eyes (34 patients) treated using the Automatic Corneal Shaper and the Keracor 117CT spot-scanning excimer laser were included. All eyes had best-corrected vision of 20/25 or better preoperatively. We measured spectacle refraction, visual acuity, and mesopic vision without and with glare (Nyktometer, Rodenstock) both preoperatively and 1 year after LASIK. Results were evaluated in three groups with reference to baseline refraction, and numbers of patients who saw a contrast of 1:5 or less were compared.


RESULTS
Myopia -1 to -5 D (group 1; n = 26): Preoperatively (postoperatively), 89% (96%) (P = 0.03) of eyes identified a contrast of 1:5 or less without glare, while 65% (73%) achieved that level with glare. Myopia -5.1 to -10 D (group 2; n = 24): Preoperatively (postoperatively), 83% (75%) of eyes identified a contrast of 1:5 or less without glare, while 50% (21%) achieved that level with glare. Myopia -10.1 to -15 D (group 3; n = 11): Preoperatively (postoperatively), 73% (55%) of eyes identified a contrast of 1:5 or less without glare, while 46% (27%) achieved that level with glare.


CONCLUSIONS
LASIK seems to cause a reduction of mesopic vision under glare conditions in corrections of more than -5 D. In corrections of more than -10 D, mesopic vision without glare is reduced, too. However, differences were not statistically significant when comparing vision at contrasts of 1:5 and lower. In addition, mesopic is considerably reduced in high myopes even preoperatively.
Knorz
M C
MC
Baylor College of Medicine, Houston, Texas, USA.
Hugger
P
P
Jendritzka
B
B
Liermann
A
A
D000328:Adult; D015350:Contrast Sensitivity; D003623:Dark Adaptation; D005260:Female; D019466:Glare; D006801:Humans; D020731:Keratomileusis, Laser In Situ; D008297:Male; D009216:Myopia / Q000601:surgery*; D011183:Postoperative Complications / Q000209:etiology*; D011446:Prospective Studies; D014792:Visual Acuity