IOL Calcifications

Are hydrophilic IOLs more trouble than they are worth? Roibeárd O’hÉineacháin reports. Diseases of the corneal endothelium and the retina may be contraindications to the implantation of hydrophilic intraocular lenses (IOLs) because the procedures to treat the conditions put the lenses at an increased risk of calcification, said Professor Andrzej Grzybowski MD, PhD, MBA and his co-authors in an article recently in published in the American Journal of Ophthalmology. “Our aim was to start the discussion and increase awareness of the problem. First, doctors should not use hydrophilic IOLs in these clinical scenarios leading to possible future keratoplasty or pars plana vitrectomy surgeries. Secondly, patients should be informed about possible risks related to the IOL material. Finally, reimbursement agencies should acknowledge the lifelong economic impact of hydrophilic versus hydrophobic IOLs,” Prof Grzybowski told EuroTimes. A LONG-EXISTING PROBLEM He noted reports of calcification-related opacification of IOLs have appeared since the early years of this century. The opacifications in hydrophilic IOLs differed from the glistenings of hydrophobic IOLs, and their impact on vision can reach the point where the IOLs must be explanted and replaced. By comparison, glistenings in hydrophobic IOLs rarely lead to explantation. He cited a recent study by Mackart (et al)i that showed of a series of 75 opacified and explanted IOLS, 92% were hydrophilic. He added there is no association proven between calcification and IOL design or manufacturer. “Historically – that is, in the last two decades – the problem of calcification with hydrophilic IOLs was of limited importance. But new technologies, including lamellar endothelial keratoplasty and mini-invasive vitrectomies, are more and more common, and there is growing evidence for significant association of IOL calcification with these new surgical techniques. This is probably related to intracameral air/gas injection during the surgery,” Prof Grzybowski said. He noted that in a retrospective analysis by Silvia Schrotenboer and associates there was a 2.5% incidence of IOL calcification after Descemet’s membrane endothelial keratoplasty triple-procedures, and 79% of the opacified IOLs were hydrophilic.ii In another study, Peter Belin and colleagues reported opacification was observed in 2% of scleral-fixated hydrophilic Akreos® AO60 IOLs. In the same study, IOL calcification occurred in 25% of all patients who underwent DSAEK.iii “According to the existing data—which is quite limited— between 2–20% endothelial keratoplasty procedures may be related with hydrophilic IOLs opacifications. Some, up to 50%, lead to IOL explantations. No registries exist for this purpose, and it is difficult to obtain the real data,” Grzybowski said. Studies have also pointed to additional risk factors associated with hydrophilic IOL calcification. They include ocular comorbidities and possible changes in the IOL’s microenvironment, such as the breakdown of the blood-aqueous barrier, which can occur in diabetes mellitus—the main systemic disease associated with opacification formation. Complex or prolonged surgery where surgical trauma leads to increased postoperative inflammation also increases the risk. On the other hand, there is no proven association between calcification and IOL design or manufacturer. HYDROPHILIC IOLS’ VARYING POPULARITY The 2017 Global IOL Market Shares for Optic Materials reported a 56% share for hydrophobic acrylic, 29% for hydrophilic acrylic, 12% for PMMA, and 3% for silicone. In Europe, hydrophilic IOL use ranges from less than 5% (Finland) to 45% (Poland). “There are many reasons for that: differences among EU countries in healthcare organisation – we cannot compare the system in Finland with Poland or Germany – and differences in the reimbursement regulations between EU countries. Obviously, hydrophilic IOLs are much cheaper than hydrophobic ones,” he noted. One of the proposed advantages of hydrophilic IOLs compared to hydrophobic IOLs is they are injectable through incision sizes lower than 2.0 mm, compared to a minimum incision size of 2.2 mm for injecting hydrophobic IOLs, Prof Grzybowski said. But he argues that in real life, using an incision smaller than 2.2 mm is of little, if any, additional benefit. Therefore, most surgeons use an incision size of at least 2.2 mm. “I personally do not see any argument [in using] hydrophilic IOLs when hydrophobic IOLs are available. However, we must note that our present understanding of the pathophysiology of hydrophilic IOLs’ opacification is rather limited, and we still cannot truly evaluate the range of the problem. But finally, even the real risk of opacification is closer to 2% than 20%, better to avoid it, especially when we have an option related with much smaller risk,” Prof Grzybowski added. The article, “Should we abandon hydrophilic intraocular lenses?” was published in the American Journal of Ophthalmology (2021), doi: https://doi.org/10.1016/j.ajo.2021.11.021. The paper’s co-authors were Reda Zemaitiene, Agne Markeviciute, and Raimo Tuuminen. i BMJ Open Ophthalmology 2021. ii Schrittenlocher et al, American Journal of Ophthalmology. 2018; 190: 171–178. iii Belin et al, Journal of VitreoRetinal Diseases. 2021; 5(2): 157–162. Andrzej Grzybowski MD, PhD, MBA, is a Professor of Ophthalmology and Chair of Department of Ophthalmology, University of Warmia and Mazury, Olsztyn, Poland, and Head of Institute for Research in Ophthalmology, Foundation for Ophthalmology Development, Poznan, Poland. ae.grzybowski@gmail.com