I was in the operating room the other day and one of my residents asked, "What is better tolerated after cataract surgery: residual hyperopia or residual myopia?" I quickly answered: "residual myopia!" She mentioned that she recently read a paper in the Journal of Cataract & Refractive Surgery that suggested otherwise. We immediately pulled the paper to review and discuss.
Dr Steven Schallhorn and colleagues report their findings on the effect of residual astigmatism on uncorrected visual acuity (UCVA) and patient satisfaction after cataract surgery. The paper also reported patient satisfaction with residual hyperopia compared with residual myopia.
This large retrospective case series examined patients at their 3-month postoperative visit (looking only at the dominant eye, > 17,000 eyes). Results from both monofocal (+/- toric) and multifocal (+/- toric) intraocular lenses (IOLs) were examined.
Along with looking at visual outcomes, the patients were given satisfaction surveys. As expected, low residual astigmatism (0.25-0.5 D) resulted in a higher probability of achieving UCVA of 20/20. As residual astigmatism values rose (from 0.75 to 1 D), the odds ratio of achieving UCVA of 20/20 dropped significantly. At these levels of astigmatism, patients also reported statistically significant decrease in satisfaction. This is not surprising. These results were true for both monofocal and multifocal IOLs.
Of note, the axis of residual astigmatism did not seem to impact UCVA. Also, what I did find interesting was that on the whole, residual low hyperopic sphere did not decrease the chances of achieving UCVA of 20/20 significantly, and patients did not seem to mind. In comparison, mild residual myopic sphere did decrease the chances of achieving UCVA of 20/20 as well as patient satisfaction scores. Again, this was true for both monofocal and multifocal IOLs.
Per the results presented in this study, patients tend to prefer residual hyperopia to myopia. Although this is a very large, well-powered, study, the results are surprising. Certainly, depending on the IOL make, model, and optics, we know that certain amounts of myopia/hyperopia may be better tolerated. Conventional teaching is to leave patients slightly myopic. In general, I try to leave my patients as close to their target refraction as possible; for their nondominant eye, I will fudge toward myopia.
What we still can't predict for our patients is effective lens position, which has significant impact on the final visual/refractive outcome. In addition, what most surgeons know but don't really think about on a day-to-day basis is the lens tolerances for a particular diopter of lens. If you choose a +20 D IOL for your patient, the lens may actually be a +19.8 to +20.2, for example. This also adds to our unpredictability with respect to lens choice and refractive outcomes. Despite some of the limitation of this study, the results certainly made me think. What I don't know yet is if or how they will affect my refractive targeting for my patients with cataracts.
Sumit (Sam) Garg, MD, is the vice chair of clinical ophthalmology and an associate professor in the Department of Ophthalmology at the Gavin Herbert Eye Institute, University of California, Irvine. He specializes in corneal and cataract surgery as well as laser refractive surgery.
Lead image: The National Institute of Health
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Cite this: Sumit (Sam) Garg. What Is Better-Tolerated After Cataract Surgery: Residual Hyperopia or Residual Myopia? - Medscape - Apr 11, 2022.