Method for IOL Power Calculation in the Second Eye of Patients With Previous Keratorefractive Surgery

Area of Science:

• Ophthalmology
• Refractive Surgery
• Cataract Surgery

Background:

• Calculating intraocular lens (IOL) power for the second eye in patients with prior keratorefractive surgery presents unique challenges.
• Accurate IOL power calculation is crucial for achieving desired refractive outcomes after cataract surgery in these complex cases.

Purpose of the Study:

• To describe and evaluate a novel method, termed the Delta K method, for calculating IOL power in the fellow eye of patients who have undergone previous keratorefractive surgery.
• To compare the efficacy of the Delta K method against established formulas and intraoperative aberrometry.

Main Methods:

• The Delta K method utilizes postoperative outcomes from the first eye to derive a 'Real K' value.
• This 'Real K' is adjusted by the difference in simulated keratometry between the two eyes to calculate the second eye's 'Real K'.
• The calculated 'Real K' is then used in the Holladay IOL Consultant software as an 'alternate K' for IOL power determination, with outcomes compared to intraoperative aberrometry, Haigis-L, and Barrett True-K No History formulas.

Main Results:

• The Delta K method demonstrated a significantly lower mean error compared to the Haigis-L and Barrett True-K No History formulas (P < .05).
• Mean absolute error for the Delta K method was significantly better than the Haigis-L formula and comparable to intraoperative aberrometry and the Barrett True-K No History formula.
• The Delta K method's performance was on par with intraoperative aberrometry regarding mean error (P = .25) and mean absolute error (P = .81).

Conclusions:

• The Delta K method provides accurate IOL power calculations for the second operative eye in patients with a history of keratorefractive surgery.
• Its mean absolute error is comparable to the Barrett True-K No History formula and intraoperative aberrometry.
• The Delta K method offers a valuable alternative for optimizing refractive outcomes in this challenging patient population.