Giacomo Savini1, Kazuno Negishi2, Kenneth J Hoffer2, Domenico Schiano Lomoriello2. 1. From the G.B. Bietti Foundation IRCCS (Savini, Schiano Lomoriello), Rome, Italy; the Department of Ophthalmology (Negishi), Keio University School of Medicine, Hospital, Tokyo, Japan; Stein Eye Institute (Hoffer), University of California, Los Angeles, and St. Mary's Eye Center (Hoffer), Santa Monica, California, USA. Electronic address: giacomo.savini@alice.it. 2. From the G.B. Bietti Foundation IRCCS (Savini, Schiano Lomoriello), Rome, Italy; the Department of Ophthalmology (Negishi), Keio University School of Medicine, Hospital, Tokyo, Japan; Stein Eye Institute (Hoffer), University of California, Los Angeles, and St. Mary's Eye Center (Hoffer), Santa Monica, California, USA.
Abstract
PURPOSE: To evaluate the results of intraocular lens (IOL) power calculation using different corneal power measurements provided by an optical biometer combined with a dual Scheimpflug analyzer and a Placido disk topographer (Galilei G6). SETTING: G.B. Bietti Foundation, Rome, Italy, and Keio University Hospital, Tokyo, Japan. DESIGN: Evaluation of diagnostic technology. METHODS: Consecutive patients having cataract surgery were enrolled. The IOL power was calculated with the Barrett Universal II, Haigis, Hoffer Q, Holladay 1, and SRK/T formulas. Different options were used to calculate the corneal power: simulated keratometry (K) based on anterior corneal surface measurements only and total corneal power (TCP) based on ray tracing through both corneal surfaces. Three TCP measurements (TCP1, TCP2, and TCP-IOL) were evaluated. RESULTS: The study analyzed 118 eyes. The mean values of simulated K (43.74 diopters [D] ± 1.40 [SD]), TCP1 (43.13 ± 1.35 D), TCP2 (41.87 ± 1.30 D), and TCP-IOL (42.62 ± 1.35 D) were significantly different (P < .0001). The best results were obtained using simulated K: the median absolute error ranged between 0.22 D and 0.29 D and the percentage of eyes with a prediction error of ±0.50 D or less, between 76.2% and 84.7%, depending on the formula. After constant optimization, the results using any TCP value and simulated K were similar with no statistically significant differences. CONCLUSIONS: Biometric measurements provided by the Scheimpflug-Placido optical biometer can be used to accurately calculate the IOL power. Simulated K and TCP led to similar outcomes after constant optimization.
PURPOSE: To evaluate the results of intraocular lens (IOL) power calculation using different corneal power measurements provided by an optical biometer combined with a dual Scheimpflug analyzer and a Placido disk topographer (Galilei G6). SETTING: G.B. Bietti Foundation, Rome, Italy, and Keio University Hospital, Tokyo, Japan. DESIGN: Evaluation of diagnostic technology. METHODS: Consecutive patients having cataract surgery were enrolled. The IOL power was calculated with the Barrett Universal II, Haigis, Hoffer Q, Holladay 1, and SRK/T formulas. Different options were used to calculate the corneal power: simulated keratometry (K) based on anterior corneal surface measurements only and total corneal power (TCP) based on ray tracing through both corneal surfaces. Three TCP measurements (TCP1, TCP2, and TCP-IOL) were evaluated. RESULTS: The study analyzed 118 eyes. The mean values of simulated K (43.74 diopters [D] ± 1.40 [SD]), TCP1 (43.13 ± 1.35 D), TCP2 (41.87 ± 1.30 D), and TCP-IOL (42.62 ± 1.35 D) were significantly different (P < .0001). The best results were obtained using simulated K: the median absolute error ranged between 0.22 D and 0.29 D and the percentage of eyes with a prediction error of ±0.50 D or less, between 76.2% and 84.7%, depending on the formula. After constant optimization, the results using any TCP value and simulated K were similar with no statistically significant differences. CONCLUSIONS: Biometric measurements provided by the Scheimpflug-Placido optical biometer can be used to accurately calculate the IOL power. Simulated K and TCP led to similar outcomes after constant optimization.
Authors: Joaquín Fernández; Manuel Rodríguez-Vallejo; Javier Martínez; Ana Tauste; David P Piñero Journal: J Ophthalmol Date: 2019-05-14 Impact factor: 1.909