The accuracy of IOL power calculations continues to improve with the use of modern instruments for biometry, updated formulas, and constant optimization. However, unusual eyes still present a challenge, and residual refractive error still occurs in a clinically significant proportion of normal cases, said Giacomo Savini, MD.
Dr. Savini also emphasized the importance of constant optimization for improving refractive outcomes with IOL implantation. The process has been demonstrated to result in an increase in the percentage of eyes with a residual refractive error within 0.5 D of target and in lower overall mean and median absolute errors.
Surgeons using published formulas can do the optimization themselves by back-calculating for each patient the constant that would have resulted in zero prediction error and then averaging the constant values for a series of patients. Surgeons using unpublished formulas could contact the developers who may perform the calculations for them.
Most optical biometers have integrated software to perform the calculations, and that involves entry of the IOL power used and the postoperative refraction.
“I suggest all surgeons take the time to optimize their constants so that they can achieve the best outcomes,” Dr. Savini concluded.
Giacomo Savini, MD
E: [email protected]
This article is based on a paper presented by Dr. Savini at the 37th Congress of the European Society of Cataract and Refractive Surgeons. Dr. Savini is a consultant to, a speaker for, and/or receives research support from companies that manufacture IOLs and instruments for biometry.