Managing a Cataract Surgery Refractive Miss

Despite advances in techniques and technologies used to calculate IOL power for patients undergoing cataract surgery, cases of significant residual refractive error still occur. Multiple management options exist, and multiple factors influence the decision about which to choose.

When it comes to cases involving a moderate refractive miss, Zaina Al-Mohtaseb MD believes lens exchange is preferred—particularly for US surgeons—while William F Wiley MD says there are many reasons to implant a piggyback secondary lens instead.

Dr Al-Mohtaseb acknowledged that arguments can be made favouring piggyback IOLs based on better refractive outcomes and lower risk for intraoperative complications.

“However, it is important to note that a lot of the refractive outcome data are from studies done outside the US, where there are sulcus-based IOLs that may be safer and more stable than the options available in the US,” she said.

“And there are ways to decrease the risk of complications when performing IOL exchanges, especially by making sure to place the new lens in the bag or capture the optic in the capsulorhexis. There is a reasonably high risk for IOL decentration if an IOL is placed in the sulcus without optic capture.”

To optimise success with IOL exchange, Dr Al-Mohtaseb suggested waiting three months for refractive stability, using plenty of ophthalmic viscosurgical devices, and taking extreme care manipulating the IOL to avoid iatrogenic zonular loss.

She noted iris capture, chafing, and pigment release with the potential for pupillary block and pigmentary glaucoma can occur with piggybacked IOLs. Furthermore, although studies show good refractive outcomes after piggyback IOL implantation, there can still be a refractive surprise.

“Imagine if a patient is already upset because of a refractive miss after the initial surgery and winds up with the opposite refractive error after undergoing a piggyback IOL procedure,” Dr Al-Mohtaseb said.

The case for piggybacking

Dr Wiley observed numerous study results support the safety and efficacy of implanting a piggyback IOL to manage cases of residual refractive error after cataract surgery. Perhaps the most compelling argument for choosing this approach versus performing an IOL exchange relates to the greater overall ease of implanting a secondary lens, he said.

“Anyone who has done an IOL exchange will know that they are likely to lose sleep the night before one of these cases, whereas you can expect to go home early when the surgical schedule has a piggyback IOL case because the procedure is that easy. For me, a piggyback IOL is the easiest case I can do in a month, but an IOL exchange could be the hardest case I will do all year.”

He outlined several issues to consider for guiding the approach to managing a refractive miss. The length of time elapsed since the initial surgery is one factor. If the primary surgery was done more than 12 months earlier, a piggyback IOL should be the obvious choice since returning to the capsular bag after such a long interval carries the risk for a variety of complications, including cystoid macular oedema, IOL decentration, and vitreous loss.

The presence of comorbidities that make IOL exchange more complicated, such as pseudoexfoliation or YAG capsulotomy, also favours a piggyback procedure.

Dr Wiley considers eyes with a history of refractive surgery as “go-to” cases for implanting a piggyback IOL.

“These eyes had an elevated risk for a refractive miss in the initial surgery, and it is hard to accurately correct any residual refractive error because they have epithelial hyperplasia,” he explained.

“Likely, they do not have significant residual astigmatism that needs to be corrected because it was already treated at the time of the laser refractive surgery. Therefore, the lack of piggyback IOLs for toric correction in the US is not an issue in these cases.”

A piggyback IOL is also ideal for patients with a refractive error and complaints of negative dysphotopsias because implanting the second lens in the sulcus will treat both problems.

One situation where Dr Wiley prefers an IOL exchange is if another doctor performs the cataract procedure and the patient complains that the surgeon put in the wrong lens. His reasoning relates to the psychological reaction a patient may have to the idea of undergoing a procedure that does not remove the “wrong lens.”

Dr Wiley’s preferred IOL for piggybacking is the three-piece acrylic AR40e (Sensar, Johnson & Johnson Vision) with a rounded edge optic that limits the risk for pigment dispersion. Addressing the potential for interlenticular opacification (ILO) between two acrylic IOLs, Dr Wiley said the problem has primarily been reported in studies of rabbits, which have a brisker inflammatory response than humans—particularly when both IOLs are placed in the capsular bag.

“Furthermore, we have debunked the myth about the risk of ILO with two acrylic IOLs in a retrospective study,” Dr Wiley said. “I think there will not be any problem if one IOL is in the sulcus and the other in the bag.”

Drs Al-Mohtaseb and Wiley spoke at AAO 2023 Refractive Surgery Subspecialty Day in San Francisco, US.

Zaina Al-Mohtaseb MD is a cataract, refractive, and corneal surgeon and director of research at Whitsett Vision Group and a clinical associate professor of ophthalmology at Baylor College of Medicine, both of Houston, Texas, US. zaina1225@gmail.com

William F Wiley MD is medical director at the Cleveland Eye Clinic, Cleveland, Ohio, US. DrWiley@ClevelandEyeClinic.com