Zonal Analysis Of Corneal Irregular Astigmatism Reveals Distinct Corneal Optical Profiles After Clear And Wfo Lasik

Although an increase in spherical aberration within the 6-mm zone after refractive surgery has been reported, data on central corneal changes that directly influence visual quality remain limited. This study aimed to analyze pre- and postoperative visual acuity, refractive outcomes, and regional corneal higher-order aberrations following corneal lenticule extraction for advanced refractive correction (CLEAR) and WFO LASIK (WFO).

First Samsung Eye Clinic, Seoul, Republic of Korea.

This retrospective study included 142 eyes (WFO: 42 eyes; CLEAR: 100 eyes). Generalized Estimating Equations (GEE) were used to compare postoperative outcomes at 3 months, adjusting for preoperative spherical equivalent (SE), keratometry, and astigmatism. Parameters evaluated included uncorrected distance visual acuity (UDVA), Alpins vector analysis, corneal Q-value, and area-specific corneal higher-order aberrations across 2.0 to 7.0 mm zones.

At 3 months, postoperative SE was −0.44 ± 0.10 D in the WFO group and −0.25 ± 0.02 D in the CLEAR group. No significant differences between two groups were found in the astigmatic Correction Index or in induced coma and trefoil within the 6-mm zone. For anterior corneal spherical aberration, there was no difference within the 6-mm zone. Beyond 6 mm, spherical aberration increased significantly in the WFO group compared with the CLEAR group (p < .05). Within the central area, the WFO group demonstrated a significant decrease in all zones except the 2-mm zone (p < .05). Postoperative Q-values at 6mm were significantly lower (more prolate) in the CLEAR group (0.22 ± 0.03) than in the WFO group (0.46 ± 0.02, p = .025).

Both WFO and CLEAR provide excellent visual and refractive results. However, CLEAR demonstrates superior preservation of preoperative corneal asphericity and spherical aberration in most areas. This advantage suggests that CLEAR may offer better quality of vision under mesopic conditions compared to WFO LASIK.