Best timing for biometry

Intraoperative aberrometry is a promising tool to aid cataract surgeons in achieving better postoperative refractive outcomes, particularly in challenging cases of high myopia or toric IOL implantation, according to Valentijn Webers MD. “Based on the results of our study, we can conclude that intraoperative aberrometry is significantly more accurate compared to the commonly used preoperative calculator SRK/T for a general population,” he told delegates attending the XXXV Congress of the ESCRS in Lisbon. Dr Webers added that while intraoperative aberrometry was only slightly more accurate compared to the Hill-RBF and Barrett Universal II online calculators in a population of highly myopic patients, it was significantly more accurate compared to the Barrett Toric Calculator for toric IOL implantations. Dr Webers presented results from a single-centre study carried out at the University Eye Clinic Maastricht, the Netherlands, comparing the prediction error in postoperative spherical equivalent (SE) by intraoperative aberrometry (ORA, Alcon) and preoperative calculations using several different methods: SRK/T formula, online available Barrett Universal II and Hill RBF calculators and the online Barrett Toric Calculator. Patients were divided into two main groups: a non-toric IOL group of 151 eyes, 111 of which had a monofocal lens implanted, and a second group of 40 eyes that received a multifocal IOL. The mean prediction error, defined as the absolute difference between the achieved and the predicted SE, was significantly lower for the ORA compared to SRK/T. The percentage of patients with an SE less than or equal to 0.25D was 63% for the ORA and 48% for the SRK/T. The figures for eyes less than 0.50D SE was 89% for the ORA and 74% for SRK/T. For the high myopic eyes, defined as those with an axial length greater than 26mm, the mean prediction error was 0.20D for ORA, and 0.25D for Hill-RBF, 0.26D for Barrett Universal II and 0.35D for SRK/T. For the 40 toric IOL patients, the mean corneal astigmatism was 2.44D and the average IOL power was 18.62. Four types of toric lenses were used, the majority of which were Alcon SN6ATx models in 31 patients (77%). Comparing ORA with the Barrett Toric Calculator, the mean absolute prediction error was 0.24D for the ORA and 0.36D for Barrett. The prediction error was ≤0.25D and ≤0.50D in 40% and 78% of cases respectively with the Barrett Calculator, compared to 75% and 90% when performed using the ORA. Valentijn Webers: valentijn.webers@mumc.nl

Tags: biometry