Giacomo Savini1, Rosa Abbate2, Kenneth J Hoffer3, Alessandro Mularoni4, Aurelio Imburgia4, Luca Avoni5, Domenico D'Eliseo5, Domenico Schiano-Lomoriello6. 1. IRCCS Fondazione Bietti, Rome, Italy. Electronic address: giacomo.savini@alice.it. 2. Eye Clinic, Department of Neurosciences, and Reproductive Sciences and Dentistry, University of Naples Federico II, Naples, Italy. 3. Stein Eye Institute, University of California, Los Angeles, California, USA; St. Mary's Eye Center, Santa Monica, California, USA. 4. Department of Ophthalmology, Ospedale di Stato della, Repubblica di San Marino. 5. Department of Ophthalmology, Santa Maria delle Croci Hospital, Ravenna, Italy. 6. IRCCS Fondazione Bietti, Rome, Italy.
Abstract
PURPOSE: To assess the refractive accuracy of different formulas for intraocular lens (IOL) power calculation in eyes with keratoconus. SETTING: IRCCS Fondazione Bietti, Rome, Italy. DESIGN: Multicenter retrospective interventional study. METHODS: A consecutive series of eyes with keratoconus that had cataract surgery were evaluated. Keratometry, anterior chamber depth, and axial length were measured preoperatively with optical biometry; IOL power was calculated with the Barrett Universal II, Haigis, Hoffer Q, Holladay 1, and SRK/T formulas. Subjective refraction was assessed at 1 month. The mean prediction error (PE), median absolute error (MedAE) and percentage of eyes with a PE within ±0.50 diopters (D), ±0.75 D, and ±1.00 D were calculated. RESULTS: The final spherical equivalent was -0.52 D ±1.61 (SD). In the whole sample (41 eyes), the mean PE was positive (hyperopic surprise) with all formulas; the lowest PE (0.91 D) and MedAE (0.62 D) were obtained with the SRK/T formula. In stage I eyes (n = 21), the MedAE ranged between 0.43 and 0.91 D; the SRK/T formula achieved the lowest MedAE and the highest rate of eyes with a PE within ±0.50 (61.9%). In stage II eyes (n = 13), the MedAE ranged between 0.75 D and 1.50 D; the SRK/T formula achieved the lowest MedAE and the highest rate of eyes with a PE within ±0.50 (30.8%). In stage III eyes (n = 7), the MedAE was higher than 2.50 D with all formulas. CONCLUSIONS: In keratoconus eyes, all formulas led to a hyperopic refractive outcome. The SRK/T was the most accurate formula. The results were worse in advanced stages of the disease.
PURPOSE: To assess the refractive accuracy of different formulas for intraocular lens (IOL) power calculation in eyes with keratoconus. SETTING: IRCCS Fondazione Bietti, Rome, Italy. DESIGN: Multicenter retrospective interventional study. METHODS: A consecutive series of eyes with keratoconus that had cataract surgery were evaluated. Keratometry, anterior chamber depth, and axial length were measured preoperatively with optical biometry; IOL power was calculated with the Barrett Universal II, Haigis, Hoffer Q, Holladay 1, and SRK/T formulas. Subjective refraction was assessed at 1 month. The mean prediction error (PE), median absolute error (MedAE) and percentage of eyes with a PE within ±0.50 diopters (D), ±0.75 D, and ±1.00 D were calculated. RESULTS: The final spherical equivalent was -0.52 D ±1.61 (SD). In the whole sample (41 eyes), the mean PE was positive (hyperopic surprise) with all formulas; the lowest PE (0.91 D) and MedAE (0.62 D) were obtained with the SRK/T formula. In stage I eyes (n = 21), the MedAE ranged between 0.43 and 0.91 D; the SRK/T formula achieved the lowest MedAE and the highest rate of eyes with a PE within ±0.50 (61.9%). In stage II eyes (n = 13), the MedAE ranged between 0.75 D and 1.50 D; the SRK/T formula achieved the lowest MedAE and the highest rate of eyes with a PE within ±0.50 (30.8%). In stage III eyes (n = 7), the MedAE was higher than 2.50 D with all formulas. CONCLUSIONS: In keratoconus eyes, all formulas led to a hyperopic refractive outcome. The SRK/T was the most accurate formula. The results were worse in advanced stages of the disease.