Abstract
Abstract: :
Purpose: To evaluate the outcomes of corneal wavefront guided laser in situ keratomileusis(LASIK) for virgin eyes in visual acuity, contrast sensitivity, corneal shape and corneal wavefront aberrations. Methods:This study included 57 myopic virgin eyes of 30 patients with spherical equivalence –4.50±1.46D(–1.63 to –7.88D), astigmatism less than 2.5D. The corneal topography system: Keratron Scout (Opticon 2000, Milano, Italy) was used to measure anterior corneal shape and to analyze the anterior corneal wavefront aberrations preoperatively and/or postoperatively. The corneal wavefront aberration data obtained from above analyses combined with manifest refraction were linked to a flying spot scanning excimer laser refractive system: ESIRIS (Schwind Eye–Tech. Solution GmbH, Kleinostheim, Germany) with its Optimized Refractive Keratectomy(ORK) software to treat the myopic patients without any prior refractive treatment. In addition to visual acuity, contrast sensitivity (CSV–1000E, Vector Vision, San Diego, CA) with and without glare was evaluated for the visual quality postoperatively. Results: After one month of following–up, all the eyes but two got uncorrected visual acuity(UCVA) 1.0 or better. The monocular contrast sensitivity(CS) without glare didn’t change significantly except for a slight reduction at the 12cpd frequency(P=0.002). The monocular contrast sensitivity with glare reduced at 3,12,18cpd(P<0.05), but not at 6cpd(P>0.05). Spherical aberration(SA), coma and the higher–order root–mean–square (HO–RMS) value of the cornea increased significantly(P<0.05 paired samples t test) after the treatment either with 6mm or 3mm pupil diameter. The amount of achieved correction was positively correlated with the changes of SA, coma and HO–RMS(P<0.01) either with 6mm or 3mm pupil diameter, except for coma with 6mm pupil diameter(P>0.05). The changes of eccentricities were negatively correlated with the amount of achieved correction (P<0.01). The changes of both SA and HO–RMS(6mm pupil) value were negatively correlated with the change of either Ef or Es(P<0.01). Conclusions: Evaluations of the early results showed that corneal wavefront guided LASIK for myopic virgin eyes can get good result in both visual acuity and mesopic contrast sensitivity level with and/or without glare. The increasing in corneal higher order aberrations has significant correlation with the achieved correction after the treatment and the changes of corneal shape from prolate to oblate shape.
Keywords: refractive surgery: optical quality • refractive surgery: corneal topography • refractive surgery: LASIK