Keys to eliminating errors

Rooting out surgical errors

Hunting high and low for accuracy in toric IOL implantations. Dermot McGrath reports

Outcomes after toric IOL implantation are influenced by numerous factors including preoperative patient selection, biometry, intraoperative alignment, surgical technique and postoperative care, according to Bartlomiej Kaluzny MD, PhD at the 25th Virtual ESCRS Winter Meeting.

Discussing the options of toric IOL implantation for patients at the extremes of low and high astigmatism, Dr Kaluzny, who is Professor of Ophthalmology and Head of Division of Ophthalmology and Optometry, Department of Ophthalmology, Collegium Medicum of Nicolaus Copernicus University, Bydgoszcz, Poland, said that while glasses or contact lenses are available to treat as little as 0.25D of astigmatism, no such option exists for toric lenses.

“We know that greater than 0.50D of astigmatism can degrade visual performance, including reading speed and contrast sensitivity. We also know that small amounts of residual or untreated astigmatism are a leading cause of patients’ dissatisfaction with multifocal IOLs and monovision. And yet, when we check what is available on the market, the lowest available cylinder power at the IOL plane is 1D, which corresponds to 0.67D at the corneal plane,” he said.

Several sources of error lie behind the difficulty in obtaining predictable and accurate outcomes with toric IOLs, especially low power, noted Dr Kaluzny.

“Keratometry readings from different devices are not always the same and integrated K is significantly more accurate than a value from a single device. Both the anterior and posterior corneal surfaces contribute to refractive power but are not always taken into account in preoperative measurements. Modern corneal tomographers have improved greatly in recent years but individual measurements may still be subject to significant variation,” he said.

Although the use of intraoperative aberrometry has helped to improve accuracy, the technology is still not widely available, said Dr Kaluzny.

Surgically induced astigmatism (SIA) remains the main source of error, he said.

“Even with small incisions and fixed meridians, the SIA is highly variable, especially in more curved corneas. Studies have shown not only a high standard deviation in SIA by different surgeons but also in the results produced by the same surgeon. So, we cannot perform reliable and reproducible SIA even if we use microincision cataract surgery,” he said.

Ensuring correct toric IOL alignment has improved in recent years with the introduction of digital markers, said Dr Kaluzny.

Nevertheless, it is important to remember that the eye evolves over time and that includes corneal astigmatism values.

“Even if we are on target immediately after the surgery and for weeks and months postoperatively, corneal astigmatism continues to change towards against-the-rule astigmatism over at least 20 years after cataract surgery. This change was found to be similar in eyes that did not have surgery, so our results may deteriorate in the future,” he said.

To sum up, “in my opinion industry people think that we are not ready for lower cylinder power IOL”.

2020 2021

Applications are open for the Peter Barry Fellowship 2021. This Fellowship commemorates the immense contribution made by the late Peter Barry to ophthalmology and to the ESCRS.

The Fellowship of €60,000 is to allow a trainee to work abroad at a centre of excellence for clinical experience or research in the fi eld of cataract and refractive surgery, anywhere in the world, for 1 year.

Applicants must be a European trainee ophthalmologist, 40 years of age or under on the closing date for applications and have been an ESCRS trainee member for 3 years by the time of starting the Fellowship.

The Fellowship will be awarded at the ESCRS Annual Congress in 2021, to start in 2022.

To apply, please submit the following:

 A detailed up-to-date CV  A letter of intent of 1-2 pages, outlining which centre you wish to attend and why  A letter of recommendation from your current

Head of Department  A letter from your potential host institution, indicating that they will accept you if successful

Closing date for applications is 1 May 2021

Applications and queries should be sent to programme@escrs.org