Improved contrast sensitivity and visual acuity after wavefront-guided laser in situ keratomileusis: in-depth statistical analysis.
OBJECTIVE
To evaluate changes in contrast sensitivity and visual acuity following wavefront-guided laser in situ keratomileusis (LASIK) procedures with the Visx CustomVue system.


METHODS
Six clinical sites that participated in an Investigational Device Exemption clinical study.


METHODS
Two hundred seventy-four myopic astigmatic eyes (spherical equivalent range -0.63 to -6.00 diopters) completed 6 months of follow-up examinations. Wavefront-guided procedures using the WaveScan aberrometer and Star S4 excimer laser system with variable spot scanning were performed at 6 clinical locations. Visual acuity and contrast sensitivity under photopic, mesopic, and mesopic-with-glare lighting conditions were tested preoperatively and over a 6-month follow-up period. This study was a retrospective analysis of contrast sensitivity data with controls for the effects of retinal magnification, mesopic pupil size, and the influence of prior soft contact lens wear on visual outcome.


RESULTS
Patients experienced statistically significant improvements in contrast sensitivity at all spatial frequencies and under all lighting conditions (P<.05, Student t test). Contrast sensitivity under mesopic conditions with glare improved in 40% of patients. There was more improvement at higher (12 cycles per degree [cpd], 18 cpd) than lower (3 cpd) spatial frequencies. No correlation was found between mesopic pupil size and contrast sensitivity. Results stratified by spectacle or soft contact lens wear were similar. Soft contact lens wearers had slightly higher disability glare scores than spectacle wearers.


CONCLUSIONS
A significant number of patients experienced improved corneal optical quality after wavefront-guided LASIK. The contrast sensitivity in most patients was unchanged. Contrast sensitivity improved in a significant number of patients. There was no correlation between mesopic pupil size and mesopic or mesopic-with-glare contrast performance. Spectacle wearers improved more than soft contact lens wearers.
Visx, Inc., Advanced Medical Optics, Inc., Santa Clara, California 95051, USA. ashley.tuan@amoi-inc.com
Kuang-mon Ashley
KM
Tuan
Junzhong
J
Liang
D000328:Adult; D001251:Astigmatism / Q000601:surgery*; D003261:Contact Lenses; D015350:Contrast Sensitivity / Q000502:physiology*; D003315:Cornea / Q000503:physiopathology*; D003627:Data Interpretation, Statistical; D005139:Eyeglasses; D006801:Humans; D020731:Keratomileusis, Laser In Situ / Q000379:methods*; D009216:Myopia / Q000503:physiopathology / Q000601:surgery*; D011184:Postoperative Period; D011680:Pupil / Q000502:physiology; D014792:Visual Acuity / Q000502:physiology*