Corneal Asphericity and Higher-Order Aberrations after FS-LASIK and Trans-PRK for Myopia

Area of Science:

• Ophthalmology
• Corneal Surgery
• Refractive Surgery

Background:

• Femtosecond laser-assisted in situ keratomileusis (FS-LASIK) and transepithelial photorefractive keratectomy (Trans-PRK) are refractive surgery techniques.
• Assessing changes in corneal asphericity and higher-order aberrations (HOAs) is crucial for understanding visual quality after these procedures.

Purpose of the Study:

• To compare the outcomes of FS-LASIK and SPT-assisted Trans-PRK regarding corneal asphericity and HOAs.
• To evaluate the impact of these procedures on visual acuity and corneal aberrations.

Main Methods:

• A prospective study comparing FS-LASIK (88 eyes) and Trans-PRK (64 eyes) for myopia and myopic astigmatism.
• Preoperative and 6-month postoperative measurements included visual acuity, spherical equivalent (SE), corneal asphericity (Q value), and HOAs (vertical coma, horizontal coma, spherical aberration).

Main Results:

• Both procedures resulted in a flatter anterior corneal surface and increased HOAs, with no significant difference in uncorrected distance visual acuity (UDVA) or SE at 6 months.
• Trans-PRK showed significantly lower vertical coma (Z3-1) compared to FS-LASIK at 1, 3, and 6 months postoperatively.
• Changes in corneal asphericity (ΔQ) were significantly correlated with changes in HOAs (ΔHOA, ΔZ40) and preoperative refractive error.

Conclusions:

• Both FS-LASIK and Trans-PRK alter corneal morphology, leading to increased HOAs.
• Trans-PRK with SPT demonstrates an advantage by inducing less vertical coma than FS-LASIK.
• Corneal asphericity changes are a significant factor contributing to the observed aberration changes after both refractive procedures.