Intraocular lens power calculation after myopic excimer laser surgery: Selecting the best method using available clinical data.

Purpose: To compare the results of methods to calculate intraocular lens (IOL) power after myopic excimer laser surgery.

Setting: G.B. Bietti Foundation-IRCCS, Rome, Italy.

Design: Prospective interventional case series.

Methods: Eyes were classified into 4 groups: Group 1 (preoperative keratometry available, refractive change known), Group 2 (preoperative keratometry available, refractive change uncertain), Group 3 (preoperative keratometry unavailable, refractive change known), and Group 4 (preoperative keratometry unavailable, refractive change unknown). The IOL power was calculated by 19 methods. The median absolute error in refraction prediction and the percentage of eyes with a refraction prediction error within ±0.50 diopter (D) were calculated.

Results: In Group 1 (n = 30), the Savini, Seitz/Speicher/Savini, and Masket methods provided the lowest median absolute error (0.29 D, 0.35 D, and 0.34 D, respectively), with more than 70% of eyes within ±0.50 D of the predicted refraction. In Group 2 (n = 16), the Seitz/Speicher method achieved the best result (median absolute error 0.37 D), with 75% of eyes within ±0.50 D of the predicted refraction. In Group 3 (n = 18), the Masket method provided the lowest median absolute error (0.24 D), with 72.2% of eyes within ±0.50 D of the predicted refraction. In Group 4 (n = 6), the Shammas no-history method had the lowest median absolute error (0.31 D), with 83% of eyes within ±0.50 D of the predicted refraction.

Conclusion: Intraocular lens power can be accurately calculated in post-laser surgery eyes when the preoperative corneal power and refractive change are known and when they are not.

Financial Disclosure: Dr. Hoffer receives book royalties for IOL Power and formula royalties from all manufacturers using the Hoffer Q formula to ensure it is programmed correctly. No other author has a financial or proprietary interest in any material or method mentioned.