Corneal Asphericity Preservation via Spatially Selective Peripheral Stromal Volume Ablation Following...

To quantitatively appraise postoperative visual quality and to delineate the spatial corneal morphological changes occurring within the central and pericentral optical zones subsequent to ray-tracing-guided laser in situ keratomileusis (RTLASIK) compared to Q-value-guided LASIK (Q-LASIK).

Sixty eyes from 60 patients were enrolled: 30 eyes in the RT-LASIK group and 30 eyes in the Q-LASIK group with a mean preoperative spherical equivalent of -5.029 ± 1.532 diopters (D) versus -5.279 ± 1.779 D. The cornea was partitioned into three vertex-centered concentric regions: a central 0- to 3-mm optical zone, a paracentral 3- to 5-mm annulus, and a pericentral 5- to 7-mm annulus. The corneal ablation ratio (CAR) was calculated as the quotient of the preoperative-to-postoperative reduction in either corneal thickness (tCAR) or stromal volume (vCAR) divided by the absolute value of the preoperative SE.

Relative to the Q-LASIK group, the RT-LASIK group exhibited significantly superior uncorrected distance visual acuity, spherical equivalent, and 3-mm Strehl ratio 3 months postoperatively. The vCAR within the same 3- to 5-mm zone was significantly elevated in the RT-LASIK group, whereas the tCAR did not differ between groups. Furthermore, RTLASIK was associated with a significantly attenuated postoperative change in Q-value within the 5-mm zone, a more pronounced reduction in spherical aberration across all of the optical zones.

RT-LASIK conferred superior postoperative visual performance by conserving native corneal asphericity and effecting a significant reduction in spherical aberration across the entire optical zone. This optical advantage was mediated by a proportionally greater ablation of stromal volume within the paracentral 3- to 5-mm annulus.