Long-Term Impact of Phakic IOLs in Myopic Eyes

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While implantation of an iris-fixated phakic IOL provides excellent visual and refractive results in highly myopic adults, researchers have found that older age at time of surgery and age-related axial elongation adversely affected long-term predictability and efficacy.¹ Specif­ically, increasing axial length (AL) over time, possibly together with cataract formation, resulted in significant myopization. This caused a decrease in both corrected and uncorrected distance visual acuity (CDVA and UDVA).

“Iris-fixated phakic IOLs remain a valid treatment for highly myopic patients,” said Soraya M.R. Jonker, MD, at University Eye Clinic Maastricht in the Netherlands. “But our data show the possibility of axial elongation that should be taken into account” in highly myopic patients who receive one of these IOLs.

What happens after 10 years? The researchers looked for refractive and visual changes in eyes that received one of two types of iris-fixated phakic IOLs from 1998 to 2016—rigid myopic (n = 379) or rigid toric (n = 81). They found mean myopization of –0.79 D, with 52% of eyes within ±1.0 D of target.

In other 10-year findings, the researchers found that anterior chamber depth did not change over time. How­ever, there was a 1.09% incidence of retinal detachments in these patients, which was higher than that reported in studies with shorter follow-up periods (0.25%-0.39%).

The cataract effect. A subset of 24 eyes that received phakic IOLs—and later underwent explantation and cata­ract surgery—experienced a significant increase in AL of 0.11 mm per year, or 1.14 mm after 10 years.

After eight years, 10% of the IOLs were explanted because of cataract formation. The higher incidence of eyes requiring cataract surgery in this study is represent­ed by post-op changes in Snellen UDVA lines. At one year postoperatively, UDVA in 51% of eyes was similar or superior to the preoperative CDVA. By the 10-year mark, that number had fallen to 30%.

While cataract formation rates were higher in this co­hort than in other studies, the researchers attributed the cataract to older age and longer mean AL rather than to the phakic IOL itself. They stressed that the influence of cataract formation versus AL elongation on myopization remains uncertain.

Patient selection. “Applying our criteria that refractive correction should be stable for two years prior to pha­kic IOL implantation, patients with known progressive axial elongation (and accompanying refractive change) would not be advised to undergo refractive surgery of any kind,” Dr. Jonker said. “Also, older presbyopic and near-presbyopic patients are not preferred candidates for traditional monofocal phakic IOL implantation, due to their reduced accommodative capacity.”

On the other hand, healthy, near-presbyopic eyes without axi­al elongation could be candidates for a refractive lens exchange, but doctors should factor in the risk of a retinal detachment in highly myopic eyes.

Dr. Jonker advised refractive surgeons to inform highly myopic patients of the long-term changes in visual outcomes and the possi­bility of axial elongation over time after phakic IOL implantation. “Changes are likely to be very slow, but they might influence the refractive correction in the long term.”

—Miriam Karmel

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1 Jonker SMR et al. J Cataract Refract Surg. 2019;45(10):1470-1479.

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Relevant financial disclosures—Dr. Jonker: None.

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