Visual Outcome After Wavefront-guided Laser In Situ Keratomileusis Compared To Standard LASIK

Purpose:To evaluate clinical efficacy of wavefront-guided laser in situ keratomileusis compared to standard laser in situ keratomileusis for moderate and high myopia correction in the aspects of visual outcome.Methods:120 eyes of 60 subjects were studied from December 2008 to May 2009 at Ophthalmic Refractive Surgery Center (Department of Ophthalmology in Changhai Hospital). The subjects were divided into 2 groups:Wavefront-guided LASIK group and Standard LASIK group, in which group 60 eyes of 30 subjects were enrolled respectively. All subjects had removed the corneal contact lens for at least 2 weeks, had no systemic, ocular disease or previous ocular surgery and at least 6 months follow-up. After operation, all subjects had not any complication, and the uncorrected visual acuity was 20/20 or better. Pre-operative examinations were uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), routine slit-lamp examination, ophthalmoscopic examinations, corneal topography (Orbscan Bausch & Lomb) and ultrasound pachymetry (BIO&PACHY METER AL-3000,TOMEY, Japan). The following examinations were tested in order to evaluate the visual quality after operation. The contrast sensitivity under photopic condition was tested by CGT-1000 (Takagi Seiko, Japan) before and 6 months after operation. Ocular higher-order aberrations were evaluated by WaveScan WaveFrontTM System (AMO, American) before and 6 months after operation. The contrast sensitivity under mesopic condition was assessed using Mesotest II b (Oculus, Germany) 6 months after operation. The change of the contrast sensitivity and ocular higher-order aberrations was calculated. The relation between the contrast sensitivity and ocular higher-order aberrations was investigated as well.Resuts:Under photopic circumstance, the contrast sensitivity in wavefront-guided LASIK group was not significantly different from standard LASIK group before operation, whereas wavefront-guided LASIK group was significantly better than standard LASIK after operation. Post-operative photopic contrast sensitivity with glare in wavefront-guided LASIK group was significantly better than that before operation at all spatial frequency, whereas the contrast sensitivity in standard LASIK group was significantly better than pre-operation at 6.3deg,4.0deg,2.5deg,1.6deg. Under photopic circumstance with no glare, the contrast sensitivity has not yet recovered to pre-operative level at most spatial frequency. The glare caused a significantly decrease in contrast sensitivity under photopic circumstance. Post-operative mesopic contrast sensitivity in wavefront-guided LASIK group was better than that in standard LASIK group, however only under the condition with a glare, it showed a statistically significant difference between two groups. The glare caused an increase in contrast sensitivity in wavefront-guided LASIK group (the statistically difference can be found only when the Log Contrast sensitivity was 0.3), whereas in standard LASIK group, it caused a decrease(although no statistically significant difference was found). It has shown an increase in ocular higher-order aberrations, especially comalike aberration and spherical-like aberration. The change of HOAROM, Z6, Z7 and Z8 in wavefront-guided LASIK group are less than that in standard LASIK group. It is revealed that HOAROM, Z8, Z9 and Z12 were significantly associated with the change of photopic contrast sensitivity. With wavefront variances increased, the contrast sensitivity decreased.Conclusions:Wavefront-guided LASIK recovered better than that of standard LASIK group in contrast sensitivity and it help patients get better visual quality than that of standard LASIK. But its long efficacy needs more cases, more evaluation index and longer time follow-up to prove.