Intraoperative Aberrometry in the Balance
IA can boost the predictability of refractive correction but adds time to surgery.
Published: Thursday, February 1, 2024
More predictable refractive outcomes and significant clinical benefits in challenging cases (such as toric IOL implantation in patients with low levels of corneal astigmatism) can be achieved using intraoperative aberrometry (IA), according to David Pablo Piñero Llorens PhD.
“IA measures the refractive state of the eye during cataract surgery, guiding surgeons in real time for IOL power selection and positioning, as well as detecting corneal curvature changes,” Dr Llorens said. “At present, the Optiwave Refractive Analysis (ORA, Alcon) is the only model that can be purchased; it is connected to a software with its own exclusive closed database. There is another model that is not available commercially at the moment.”
According to Dr Llorens, several variables can affect the accuracy of IA measures, lowering the repeatability.
“The intracameral presence of viscosurgical devices can affect the measurement of IOL power,” he explained. “In addition, ocular surface irregularity and intraocular pressure can also play a role, as well as the lid speculum and its position, because it puts some pressure on the globe and can make some modifications to the geometry of the cornea and other structures of the anterior chamber.”
Moreover, IA comes with one issue that must be addressed. “As you can imagine, the main inconvenience is the increase in surgery length: this can lead to less surgical efficiency. We must prepare the eye for this measurement, the device for the analysis, and look at the data. On average, the use of an IA increases the overall time by 3 minutes and 45 seconds compared to normal surgical time.”
Yet one of IA measurement’s major benefits, the potential optimisation of surgical outcomes, carries a controversial aspect.
“Many studies have demonstrated that the use of the currently available generation formulas should seem sufficient to produce clinical outcomes with toric IOLs as good as we can achieve with IA.”
One of the most difficult challenges comes with IA and FLACS use in low corneal astigmatism.
“Compensation with toric IOLs will have a lower pr edictability of refractive correction, with a significant contribution of posterior corneal astigmatism and a significant impact of small IOL misalignments or rotations. However, the combination of FLACS and IA to optimise the position and calculation of a toric IOL may allow a very efficacious correction of pre-existing low to moderate corneal astigmatism,” he said.
“Intraoperative aberrometry can be useful to improve the predictability of refractive correction with toric IOLs—especially in eyes with corneas with low astigmatism—but some factors must be controlled for an accurate procedure, such as lid speculum and OVD.”
Dr Piñero Llorens spoke during the 2023 ESCRS Congress in Vienna.
David Piñero Llorens OD, PhD is Associate Professor of the Department of Optics, Pharmacology, and Anatomy at the University of Alicante, Spain. firstname.lastname@example.org