Review of Ophthalmology's blog
When Multifocal IOLs Need Corneal Surgery
By Christopher Kent, Senior Editor, Review of Ophthalmology
Clear, fully accommodative vision may be the holy grail that ophthalmologists dream of providing their cataract patients, but that goal remains elusive. In the meantime, multifocal intraocular lenses remain a popular option for allowing good vision at both near and distance—at least in select patients.
Unfortunately, to produce good outcomes, multifocal IOLs require not only careful patient selection but also very precise refractive outcomes—meaning almost no spherical or astigmatic error. Given the challenges involved in achieving that level of precision today, doctors implanting multifocal lenses often need to compensate for the limitations of the surgery by adjusting the cornea preop or postop. In the United States, where toric multifocals are still not available, that often includes managing astigmatism.
“No matter how good your biometry or nomogram is, you’ll need to touch-up an eye containing a multifocal implant about 15 percent of the time,” says Richard Mackool Sr., MD, PC, director of the Mackool Eye Institute and Laser Center and senior attending surgeon at the New York Eye and Ear Infirmary, who has been implanting multifocal IOLs for 18 years. “I’m talking about routine, normal eyes, not eyes with strange biometries or excessive astigmatism. Fifteen percent of the time you won’t be within the ±0.5 D that satisfies 90+ percent of people. That’s because effective lens position is variable from person to person. Furthermore, K-readings are variable between machines and examiners, and probably between morning and night. These are factors you can’t control for.”
At http://www.revophth.com/content/c/39243/ several experienced surgeons share their thoughts on issues relating to this, including managing preop (and possibly postop) astigmatism; the importance of setting patient expectations; deciding whether any postop change is actually necessary; how long to wait before performing an adjustment; choosing the most appropriate corneal surgery to use; deciding whether to touch-up the cornea or exchange the IOL; and special circumstances that arise when doing both eyes in a short period of time.