Trapezoidal astigmatic keratotomy. Quantification in human cadaver eyes

Area of Science:

• Ophthalmology
• Corneal Surgery

Background:

• Surgical correction of astigmatism, particularly astigmatic keratotomy, lacks a complete mechanistic understanding.
• This unpredictability in surgical outcomes necessitates further research into the contributing factors of astigmatic keratotomy procedures.

Purpose of the Study:

• To analyze the individual contributions of component parts of trapezoidal astigmatic keratotomy (AK).
• To elucidate the mechanism of astigmatism correction by different AK configurations.

Main Methods:

• Utilized a Terry keratometer to measure corneal curvature changes.
• Evaluated 3-, 4-, and 5-mm trapezoidal astigmatic keratotomies, analyzing semiradial and tangential incision effects.

Main Results:

• Semiradial incisions induced greater horizontal corneal flattening than vertical flattening, creating positive cylinder astigmatism.
• A single pair of 5-mm tangential incisions, combined with semiradial incisions, accounted for a significant percentage of the total astigmatic correction (100% for 3-mm, 87% for 4-mm, 78% for 5-mm AKs).

Conclusions:

• The study suggests that semiradial incisions are crucial for inducing astigmatic change.
• Maximal astigmatic correction may be achieved with a specific configuration of one set of tangential incisions between two sets of semiradial incisions.