Flap-induced and laser-induced ocular aberrations in a two-step LASIK procedure

Area of Science:

• Ophthalmology
• Refractive Surgery
• Optometry

Background:

• Laser in situ keratomileusis (LASIK) is a common refractive surgery procedure.
• A two-step LASIK approach involves creating a corneal flap followed by delayed laser ablation.
• Understanding induced aberrations is crucial for optimizing visual outcomes.

Purpose of the Study:

• To identify and quantify ocular aberrations induced by LASIK flap creation.
• To assess aberrations after a subsequent laser ablation in a two-step procedure.
• To compare aberration induction between different microkeratomes.

Main Methods:

• A two-step LASIK procedure was performed on 22 eyes using the Alcon LADAR-Vision laser.
• Corneal flaps were created, followed by laser ablation one month later.
• Ocular aberrations were measured preoperatively and at multiple time points post-flap creation and post-ablation using the LADARWave device.
• Two microkeratomes (Moria M2 and SKBM) were utilized, with varying hinge placements.

Main Results:

• A slight hyperopic shift was observed with the Moria M2 microkeratome after flap creation, but not with the SKBM.
• Higher-order aberrations increased significantly after flap creation with both microkeratomes, though trends were unpredictable.
• Post-laser ablation aberrations were substantially greater than those induced by flap creation alone.

Conclusions:

• LASIK flap creation induces both lower and higher-order ocular aberrations.
• The degree of lower-order aberration change is dependent on the microkeratome used.
• The significant increase in aberrations post-ablation suggests a two-step LASIK procedure is not necessary for conventional treatments.