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Worse visual outcomes correspond to higher rate of refractive growth in aphakic children
A study compared two groups of children who had undergone cataract surgery as infants, with one group receiving IOLs after surgery and the other left aphakic with contact lenses.
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A higher rate of refractive growth is associated with worse visual outcomes in eyes left aphakic after infant cataract surgery, according to a study.
That association did not occur in eyes that had received IOLs after the surgery.
A randomized clinical trial assessed results for 108 patients who underwent unilateral cataract surgery performed at 12 clinical sites throughout the U.S. as part of the Infant Aphakia Treatment Study.
Fifty-seven infants received IOLs, and 57 received contact lenses. The mean age for each group at the time of surgery was 1.8 months.
Follow-up examinations came at 1 day, 1 week, 1 month and 3 months postoperatively. They were repeated thereafter once every 3 months until the patients reached age 4 years, then at 4.25 years, 4.5 years and 5 years. Visual assessments and IOP measurements were made through 5 years as well.
Associations with RRG
The authors calculated refractive rate of growth (RRG) using a formula introduced in a study published in 2000 by McClatchey and colleagues. No statistically significant difference was seen between the mean RRG value in the contact lens group (–18 ± 11 D) and the IOL group (–19 ± 9 D). However, in the contact lens group only, a statistically significant difference was seen in the mean RRG value relative to visual acuity (–0.35, P = .01).
Lead author Scott R. Lambert, MD, said the similarity in RRG between the two groups is revealing and a useful tool in the clinic.
“We have shown that ocular growth occurs on a semi-logarithmic basis after cataract surgery in children irrespective of whether an intraocular lens is implanted,” he said. “This is helpful in trying to predict the optimal intraocular lens to implant in a child’s eye.”
Decision-making factors
But decisions on IOLs are more than a matter of plugging values into McClatchey’s formula.
“It allows a surgeon to target and approximate refractive error at a future date for a child undergoing cataract surgery and IOL implantation,” Lambert said. “However, there is a large element of unpredictability between individual patients, so the formula should be viewed as a guide rather than as a calculator.”
Despite the visual acuity results in the contact lens group, the decision whether to implant an IOL is not clear-cut.
“We have previously reported that more adverse events and additional intraocular surgeries are required when an IOL is implanted in an infant’s eye,” Lambert said. “However, wearing a contact lens is not a viable option for all children due to cost consideration or family dynamics. Therefore, while we believe that, ideally, a child with a unilateral congenital cataract should be left aphakic and the refractive error corrected with a contact lens, we acknowledge that some infants will have a better visual outcome if an intraocular lens is implanted at the time of cataract surgery.”
Lambert said he and his co-authors are assessing children in the Infant Aphakia Treatment Study at age 10.5 years.
“We will have completed these follow-up examinations by 2018 and will publish our findings thereafter,” he said. – by Joe Green
- References:
- Lambert SR, et al. J Cataract Refract Surg. 2016;doi:10.1016/j.jcrs.2016.09.021.
- McClatchey SK, et al. Ophthalmology. 2000;doi:10.1016/S0161-6420(99)00033-0.
- For more information:
- Scott R. Lambert, MD, can be reached at Byers Eye Center, 2452 Watson Court, Palo Alto, CA 94310; email: lambert7@stanford.edu.
Disclosure: Lambert reports no relevant financial disclosures.