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Hitting the mark in cataract surgery

Intraoperative tools provide useful guidance in a range of refractive situations

Cheryl Guttman Krader

Posted: Tuesday, September 1, 2020

Intraoperative tools for refractive guidance during cataract surgery can enable decision-making, especially in complex cases and for premium cataract surgery cases that demand premium results, said Kendall E Donaldson MD, MS, in a live presentation during the 2020 ASCRS Virtual Annual Meeting.

Dr Donaldson, Professor of Clinical Ophthalmology, Bascom Palmer Eye Institute, University of Miami, Miami, FL, USA, provided an overview of the available intraoperative refractive guidance systems and provided information from the published literature and case examples demonstrating their utility.

Defining intraoperative refractive guidance tools as any type of technology that is designed to assist cataract surgeons to improve refractive outcomes, she described four systems – ORA System with VerifEye+ Technology (Alcon), VERION Image Guided System (Alcon), CALLISTO Eye (Zeiss) and IntelliAxis (Lensar).

The ORA System is comprised of two components: 1) a real-time intraoperative refractometer that uses wavefront aberrometry to assess the refractive power of the eye in the phakic, pseudophakic, or aphakic states; and 2) software that analyses surgeons’ results and helps with outcomes optimisation and reporting (AnalyzOR).

“The intraoperative aberrometer is used for guiding toric IOL alignment and for IOL power selection in complex cases, such as in post-refractive, long or short eyes. It can also be useful in any case where there is discrepancy in the preoperative measurements and for confirming IOL power in patients having premium refractive cataract surgery who in particular have extremely high outcomes expectations,” Dr Donaldson said.

Published data show that use of the intraoperative aberrometer reduces enhancement rates after cataract surgery and improves refractive results in patients with a history of myopic refractive corneal surgery as well as in unusual eyes, eg, those with axial myopia.

“A study we performed found that the accuracy of toric IOL power selection was improved by the use of the ORA system in patients with significant astigmatism and a history of refractive surgery,” Dr Donaldson said.

Results of a surgeon poll also indicate that the vast majority hold favourable opinions of intraoperative aberrometry. The survey included 50 surgeons who are aware of the technology and implant at least 50 toric IOLs annually. Among those surveyed, 90% said they would want intraoperative aberrometry used in their own surgery if they had a history of a corneal refractive procedure and 80% would want it used if they were being implanted with a toric IOL.

Callisto Eye is part of a technology suite with functions that include markerless guidance for toric IOL alignment. Published evidence show that its use increases the safety and consistency for toric IOL marking. Studies also show it is very accurate and very efficient, Dr Donaldson reported.

The VERION Image Guided System uses the VERION reference unit to capture a high-resolution digital image of the eye that is used intraoperatively to guide precise positioning of femtosecond laser-created incisions and toric IOL alignment.

As a feature of the LENSAR femtosecond laser, IntelliAxis is a method for making permanent capsular marks on the steep axis that can be used for guiding toric IOL alignment intraoperatively and checking alignment postoperatively.

Dr Donaldson presented two cases that illustrated the use and benefits of intraoperative refractive guidance technology.

One case involved a 68-year-old man with a history of multiple corneal refractive procedures. He presented with 4D of astigmatism OD and 1D OS. Keratometry measurements obtained with multiple instruments showed poor agreement. Using the different measurements to calculate IOL power led to results that varied by 3.0D OD and 1.5D OS. The patient was implanted bilaterally with a monofocal IOL using the power determined with intraoperative aberrometry that fell within the suggested range. He achieved 20/20 UCDVA bilaterally, and his UCNVA was J1 OD and J2 OS.

“In cases where I am unsure, I try to err on the side of the higher-power IOL that potentially would leave the patient with a little myopia. In this case, however, I followed the guidance from the intraoperative aberrometer, and the patient did extremely well,” she said.

The second case was a 62-year-old man with early cataracts and 1.5D of against-the-rule astigmatism OU. He presented requesting a LASIK evaluation because of blurry vision but was recommended to undergo clear lens extraction because he wanted presbyopia correction.

In this case as well, the keratometry measurements did not agree. The calculated IOL powers varied across a 1.0D range. With power selection guided again by the intraoperative aberrometer,

Dr Donaldson implanted a diffractive multifocal toric IOL in both eyes. The patient achieved 20/20 UCDVA at distance and J1+ UCNVA in both eyes.

Dr Donaldson ended her discussion with the following caveat about the benefit of the intraoperative guidance tools.

“Technology has really allowed us to be our best as cataract surgeons and to improve our refractive accuracy. Outcomes, however, depend on getting accurate preoperative measurements,” Dr Donaldson said.

Providing a future perspective, she added: “The field is rapidly evolving with increased availability of adjustable IOLs and refractive indexing. We have a very exciting time ahead.”

Kendall E Donaldson: KDonaldson@med.miami.edu