New axis-marking method for a toric intraocular lens: mapping method

Area of Science:

• Ophthalmology
• Surgical Techniques
• Optical Biometry

Background:

• Accurate alignment of toric intraocular lens (IOL) astigmatism axis to the steepest corneal axis is crucial for successful refractive outcomes.
• Conventional methods for marking the corneal axis have limitations in precision.

Purpose of the Study:

• To introduce and evaluate a new axis-marking method, termed the mapping method, for toric IOL implantation.
• To compare the accuracy of the mapping method against two conventional axis-marking techniques.

Main Methods:

• The steepest corneal axis was determined using IOLMaster optical biometry.
• Three methods were evaluated: 1) manual marking with a toric reference marker, 2) marking using a horizontal slit beam, and 3) the new mapping method utilizing anterior segment photographs and conjunctival vessels as reference points.
• Accuracy was assessed by measuring axis-marking errors using anterior segment photographs.

Main Results:

• The mapping method (Method 3) achieved an average axis-marking error of 2.29±1.06°.
• Conventional Method 1 had an average error of 3.69±1.49°, and Method 2 had an average error of 3.14±1.64°.
• The mapping method was significantly more accurate than both conventional methods (P<.01 and P=.016).

Conclusions:

• The new mapping method, leveraging conjunctival vessels for reference, offers superior accuracy in toric IOL axis marking.
• This improved precision in axis marking is expected to enhance the effectiveness of toric IOL implantation.
• The mapping method presents a valuable advancement over traditional techniques for astigmatism correction surgery.