Cyclotorsion during laser in situ keratomileusis

Area of Science:

• Ophthalmology
• Refractive Surgery
• Ophthalmic Technology

Background:

• Cyclotorsion, the rotational movement of the eye, can impact the accuracy of refractive surgery.
• Excimer laser ablation, commonly used in procedures like LASIK, requires precise eye alignment for optimal outcomes.

Purpose of the Study:

• To quantify the magnitude of cyclotorsion during excimer laser ablation using a dynamic iris eye tracker.
• To assess the prevalence and direction of cyclotorsion in patients undergoing LASIK.

Main Methods:

• A retrospective analysis of 245 eyes from 137 patients who underwent LASIK for myopia.
• Cyclotorsion was measured during laser ablation using a dynamic iris eye tracker, recording maximum, average, and minimum positions.
• Data included angle of deviation displayed on the excimer laser computer screen.

Main Results:

• The mean total cyclotorsion observed was 2.181 degrees.
• A significant proportion of eyes (68.6%) showed deviation from the zero position at the start of ablation.
• Both incyclotorsion and excyclotorsion were observed, with 35.1% of eyes exhibiting mixed cyclotorsion.

Conclusions:

• Cyclotorsion is a common occurrence both before and during excimer laser ablation.
• Active rotational eye tracking is essential for compensating cyclotorsion, thereby enhancing the precision of laser vision correction procedures.