Optimising outcomes in cataract surgery

Intraoperative wavefront aberrometry (ORA, Alcon) adds value to the use of modern preoperative IOL formulas for achieving better outcomes in refractive cataract surgery, said Joaquim Neto Murta MD, PhD. Speaking at the 37th Congress of the ESCRS in Paris, France, Dr Murta said he uses the technology in all patients when he is implanting a presbyopia-correcting or toric IOL. “Patients have high expectations for their visual outcome after refractive cataract surgery and expect to decrease their dependence on spectacles. Therefore, the importance of achieving emmetropia or the targeted postoperative refraction and correcting astigmatism is greater than ever. Intraoperative wavefront aberrometry (IWA) increases refractive accuracy, improves patient outcomes and decreases the need for enhancements. I implant trifocal and toric IOLs in a high percentage of patients, and with the use of IWA in the last two years I have only done PRK in two of those cases,” said Dr Murta, Professor of Ophthalmology, University of Coimbra, Coimbra, Portugal. He added, “Using IWA gives me
happier patients who help grow my premium practice.” As evidence to support his comments, Dr Murta discussed two studies he conducted in which he analysed the impact of IWA on refractive outcomes. A non-randomised, consecutive prospective study included 86 eyes of 86 patients undergoing uncomplicated cataract surgery with implantation of a trifocal or trifocal toric IOL. Biometry measurements were obtained with an optical biometer and IOL power decisions were made using IWA. Accuracy of results Using measurements obtained two months after surgery, Dr Murta compared the accuracy of the achieved results with those predicted using three top formulas – Kane, Barrett Universal II, and Hill-RBF 2.0. The analyses showed no statistical difference between IWA and the formulas in analyses of mean arithmetic error and mean and median of the absolute prediction error. For these endpoints, however, there were numerical differences favouring IWA, and the percentage of eyes ±0.25D of target and ±0.50D of target was highest using IWA. Another study focused on eyes undergoing toric IOL implantation and compared the prediction of residual astigmatism with its use versus the toric IOL calculator incorporating the Barrett algorithm with estimation of posterior corneal astigmatism. The study included 50 eyes and found a mismatch in recommended power between IWA and the calculator in 52% of cases. Using IWA in the latter subgroup increased the accuracy of residual astigmatism prediction, Dr Murta reported. Getting good results Dr Murta offered several tips for obtaining reliable measurements with the intraoperative aberrometer. “Four simple characteristics are needed,” he said. The eye should be widely open, and the tear film should be well hydrated and uniform, but not flooded. The eye should also be well pressurised and well aligned, and surgeons should check that the intraocular state of the eye is homogeneous, clear from debris or bubbles. “Watch out for a dry cornea or pooling of moisture on the ocular surface. IOP should be set to 21mmHg, and if a toric IOL is being implanted, there should be no pressure on the limbus from the speculum,” Dr Murta advised. Other benefits of using intraoperative aberrometry are that it provides outcome analysis and astigmatism management reports that allow surgeons to assess the consistency with which they hit the refractive target and the accuracy of their outcomes for astigmatism correction. In addition, the system is continuously optimised both globally and specifically to the surgeon. “The personalisation is a very important feature,” said Dr Murta. “Each time a surgeon enters postoperative refractive outcomes, the global database will be reanalysed and updated, and the IOLs for which the surgeon has entered data will be personalised within the system.” The manufacturer recommends that the postoperative results should be obtained at follow-up at least 10 days after surgery. “In our centre, we use data from the two-month postoperative visit,” Dr Murta said. Joaquim Neto Murta: jmurta@netcabo.pt

Tags: biometry