Why are multifocal lenses for cataract surgery not suggested to some people?

Multifocal IOLs (Intraocular Lens Implants) are the most popular and successful of the various IOL designs meant to provide good uncorrected distance and near vision after cataract surgery. So why wouldn't every ophthalmologist suggest them to their patients?

There are two main reasons: 1) Multifocal IOLs work in a different way to provide near vision than the natural human lens: The "rings" in the IOL are each set at a progressively closer focal distance rather than having the lens change shape. The biggest "negative" to this is the appearance of concentric rings around lights at night (although these tends to fade away with time).

2) To work the best, the focus of the eye at distance has to be near perfect after surgery -no residual astigmatism or nearsightedness. This is more difficult to achieve than you might think. Selecting the right prescription is based on a regression analysis of past patients and not directly on the actual measurement of the prescription of the natural lens in the eye to be operated on. Even in the hands of the most precise and perfectionist eye surgeons, the accuracy of getting a perfect distance focus is plus or minus 0.5 diopters about 70% of the time. That is simply not good enough for refractive surgery (like LASIK).

So the ophthalmologist is faced with a challenge: the patient is going to be paying much more money out-of-pocket and might not be satisfied with the results. Getting it right in such cases may require more surgery or perhaps a laser adjustment of the cornea to make it right. Most ophthalmologists do not have their own laser to do LASIK with or their own operating room, if needed.

So it is easier to just recommend the single vision, or monofocal IOL.

_Written by J. Trevor Woodhams, M.D. - Chief of Surgery, Woodhams Eye Clinic