Comparison of formula accuracy for intraocular lens power calculation based on measurements by a swept-source optical coherence tomography optical biometer

PURPOSE: To analyze the results of intraocular lens (IOL) power calculation using measurements by a swept-source optical coherence tomography (SS-OCT) optical biometer.

SETTING: IRCCS G.B. Bietti Foundation, Rome, Italy.

DESIGN: Evaluation of a diagnostic test instrument.

METHODS: Preoperative measurements by the OA-2000 (Tomey Inc.) were taken in a consecutive series of patients undergoing cataract surgery with one IOL model (AcrySof SN60WF; Alcon Laboratories, Inc.). Measurements were entered into the following formulas: Barrett Universal II, Emmetropia Verifying Optical (EVO), Haigis, Hoffer Q, Holladay 1, Holladay 2, Holladay 2 with axial length adjustment, Kane, Olsen, Panacea, SRK/T, T2, and VRF. When refraction was measured at 1 month postoperatively, the mean arithmetic prediction error, the median absolute error (MedAE), and the percentage of eyes with a error of ±0.50 D or less were calculated after constant optimization.

RESULTS: We enrolled 150 eyes. All formulas yielded excellent outcomes. The MedAE ranged between 0.200 D and 0.259 D, with a statistically significant difference among formulas (P = .0004). The lowest MedAE values were obtained with the Barrett, EVO, Kane, Olsenstandalone, Radial Basis Function (RBF), and T2 formulas. The percentage of eyes with a prediction error of ±0.50 D or less ranged between 80.00% and 90.67%, with a statistically significant difference (P < .0001). The Barrett, EVO, Holladay 2 with axial length adjustment, Kane, RBF, and T2 achieved the highest percentages (≥88%).

CONCLUSIONS: Measurements provided by the SS-OCT optical biometer enable accurate IOL power calculation because all formulas yielded a prediction error within 0.50 D in at least 80% of eyes.