Abstract
Purpose: :
To compare the objective optical quality using double-pass aberrometry (OQAS, Visiométrics, Spain) in patients operated with PRK and FemtoLASIK for low to moderate myopia
Methods: :
Prospective comparative study of one hundred and thirty-four eyes of 67 patients (PRK n=38, FemtoLASIK n=29) who underwent bilateral refractive surgery. Inclusion criteria were: <40 years old myopic, preoperative cylinder <1.5D. The optical quality of each eye was measured with the OQAS preoperatively and at 1 and 3 months postoperatively using double-pass aberrometry on a 4mm pupil.The Objective Scattering Index (OSI), the Modulation Transfer Function (MTF) cut-off frequency (c/deg) and the Strehl ratio (SR) were compared at each visit
Results: :
Preoperatively there was a significant difference in the treated spherical equivalent (p<0.0001). Mean OSI was 0.56+/-0.09 in the PRK group and 0.67+/-0.10 in the FemtoLASIK group (p=0.12). The MTF cut-off frequency (c/deg) was 39.64+/-2.33 in the PRK group and 37.17+/-2.79 in the FemtoLASIK group (p=0.18). One month postoperatively mean OSI was 0.71+/-0.10 in the PRK group and 0.99 +/-0.14 in the FemtoLASIK group (p=0.002). Mean MTF cut-off frequency (c/deg) was 34.44+/-2.07 in the PRK group and 33.72+/-2.91 in the FemtoLASIK (p=0.69). Three months postoperatively mean OSI was 0.57+/-0.07 in the PKR group and 0.92+/-0.12 in the FemtoLASIK group (p<0.0001). Mean MTF cut-off frequency (c/deg) was 37.7+/-2.05 in the PRK group and 34.4+/-2.5 in the FemtoLASIK group (p=0.04).At 3 months the OSI is more important in the FemtoLASIK group (p<0.0001) and the SR is larger in the PRK group (p=0.002).
Conclusions: :
In the early postoperatory period the scatter increases and the contrast sensitivity decreases similarly in both groups.In the late postoperatory period the PRK provides a better optical quality. FemtoLASIK produces more scatter. Both techniques worsen contrast sensitivity
Keywords: myopia • refractive surgery: comparative studies • refractive surgery: optical quality