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Presbyopia-correcting IOLs provide an extended range of good vision. Not all cataract surgery patients, however, are appropriate candidates for that technology, and there are other alternatives for gaining near vision. Time must be spent in precataract surgery counseling to assess the patient's desire for spectacle independence, suitability for a presbyopia-correcting IOL, and the benefits and trade-offs of all available alternatives.
Baltimore-The expanded number of options now available for extending the range of vision after cataract surgery places an increased responsibility on the ophthalmologist to spend adequate time preoperatively reviewing each patient's personal goals for vision and the benefits and trade-offs of the various alternatives for pseudophakic correction, said Oliver D. Schein, MD, MPH, here at the Current Concepts in Ophthalmology meeting.
"When we had fewer options to offer, our preoperative discussions were correspondingly briefer. Even with the advances in IOL technology, I still find that a conventional monofocal implant is the choice preferred by the majority of my patients," said Dr. Schein, the Burton E. Grossman Professor of Ophthalmology, Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore. "Nevertheless, I believe it is incumbent upon all surgeons to spend ample time in preoperative counseling so that he or she understands the patient's desires and the patient understands what options are available."
Even patients with conventional monofocal IOLs will derive some near vision benefit from pseudoaccommodation and pupillary constriction, he said, and a standard spherical IOL provides some added benefit for extending the range of focus because it adds spherical aberration to the optical system. In addition, Dr. Schein said, some patients can derive some near vision benefit by virtue of having natural multifocality in the cornea or if the eye is slightly myopic and has some against-the-rule astigmatism. Alternatively, the surgeon can implant a monofocal IOL with a power target that will provide the patient with monovision.
At the other end of the spectrum of options are the IOLs designed to be presbyopia-correcting, including an accommodating IOL (crystalens, eyeonics) or one of the new multifocal or apodized diffractive IOLs (ReZoom, Advanced Medical Optics; AcrySof ReSTOR, Alcon Laboratories).
Is the patient a candidate?
"Each of these implants has its individual strengths and limitations. Therefore, from a practical perspective, whether a surgeon offers one of these options, two, or all three, it is important to spend adequate time discussing the features of the technology available and in determining whether the patient is an appropriate candidate," Dr. Schein said.
The most important criterion in selecting a patient for a presbyopia-correcting IOL is the individual's desire for reduced spectacle dependence. In the absence of that interest, there is probably no role for implanting a presbyopia-correcting IOL, said Dr. Schein, who is also professor of epidemiology, Bloomberg School of Public Health, Johns Hopkins University.
"If the patient primarily wants the best optical outcome, regardless of the need for spectacle or contact lens wear, then a conventional monofocal implant continues to be the IOL most likely to fulfill that goal. The trade-off of quality of uncorrected vision at one distance versus another is an important sacrifice for some patients but less critical to others," Dr. Schein said.
If the patient's definition of improved visual function includes a greater range of vision and freedom from spectacles, however, then one of the newer presbyopia-correcting IOLs can provide a possible means for achieving that goal, he said. Patients interested in that option need to understand that in gaining the advantage of an extended range of vision, they face an increased risk for problems with night-vision quality and decreased crispness of images at different distances. In addition, he said, patients need to be apprised of the differences in cost and be informed that with a presbyopia-correcting IOL, additional refractive or astigmatic surgery to fine-tune the final refraction is possible.
"Patients who understand these issues and value an increased range of vision without spectacles do very well with presbyopia-correcting IOLs," Dr. Schein said.
Aside from establishing a desire for reduced spectacle wear, several other issues should be considered when determining whether a patient is a good candidate for a presbyopia-correcting IOL, he said. In general, better outcomes and higher satisfaction rates are achieved in those who need bilateral cataract surgery versus in patients who have a unilateral cataract or are seeking refractive lens exchange. In addition, individuals who have significant myopia or hyperopia are more likely to appreciate the vision benefits of the presbyopia-correcting IOLs than are their counterparts who were emmetropic preoperatively or only mildly ametropic. Obviously, patients also need to be evaluated for other ocular pathology, particularly retinal conditions, that would limit their visual outcome.