Temporal and Spatial Flap Variability in Laser In-Situ Keratomileusis by Optical Coherence Tomography

Area of Science:

• Ophthalmology
• Corneal Surgery
• Refractive Surgery

Background:

• Laser in-situ keratomileusis (LASIK) is a common refractive surgery.
• Accurate flap thickness is crucial for successful LASIK outcomes.
• Microkeratome head selection can influence flap characteristics.

Purpose of the Study:

• To evaluate changes in LASIK flap thickness using two different microkeratome heads.
• To assess flap thickness at various corneal locations postoperatively.
• To determine the influence of microkeratome head size on flap thickness stability.

Main Methods:

• Prospective study involving 88 eyes undergoing LASIK.
• Flaps were created using 90 μm (MSU90) or 130 μm (MSU130) microkeratome heads.
• Anterior segment optical coherence tomography (OCT) measured flap thickness centrally and peripherally at 1 day, 1 week, and 1 month.

Main Results:

• No statistically significant changes in flap thickness were observed in either group over 1 month.
• The MSU90 group had a mean central flap thickness of 123-130 μm, while the MSU130 group had 142-147 μm.
• A statistically significant difference in flap thickness was noted between the two groups at all measured locations (P < 0.001).
• A positive correlation between central flap thickness and preoperative central corneal thickness was found only in the MSU90 group.

Conclusions:

• LASIK flap thickness demonstrates minimal changes within the first month postoperatively.
• The choice of microkeratome head (90 μm vs. 130 μm) significantly impacts flap thickness.
• A 90 μm microkeratome head shows a correlation between flap thickness and central corneal thickness, suggesting predictability.