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The main secret to being a successful multifocal contact lens fitter is communication.
The main secret to being a successful multifocal contact lens (CL) fitter is communication, according to Milton M. Hom, OD, FAAO, a private practitioner in Azusa, CA.
According to Dr. Hom, multifocal CLs provide better intermediate visual acuity and better near stereopsis than monovision contact lenses, and research has found that a majority of patients rate their vision with multifocals better than their vision with monovision lenses.1 In addition, the benefits of multifocals can be provided easily, as fitting a first-time presbyopic correction with multifocal lenses requires the same chair time as fitting monovision lenses.2
To ensure the best overall performance from a multifocal, it's important to establish a patient's sighting dominance. One test is the "swinging-plus" test to test the near point of convergence. Have the patient hold a +1.50 D trial lens over one eye while walking around the room. The eye with which the patient is most comfortable doing this is the near eye. Dr. Hom said he prefers to use the "hole-in-the -card" test. Have the patient look across the room through a makeshift opening with their hands and determine which eye they use for distance.
"Clarke Newman from Dallas pointed out an interesting fact about multifocal fitting to me," Dr. Hom said. "He says that sometimes there is a difference between the dominant eye and the preferred eye in a certain percentage of cases. We usually assume the dominant eye is the preferred eye, but that is not always the case. This is when switching the eye function-exchanging the distance-biased lens with the near-biased lens-will solve the problem."
Be aware that there are distinct differences in the designs of lenses from various manufacturers. Some manufacturers have dramatically different power profiles for low-add and high-add lenses: In their low-add lenses the plus power gradually increases toward the lens center for increased depth of field, while in their high-add lenses, there is a distinct central cone of greater plus power.
Other manufacturers' lenses are designed in a variety of add powers, with a center near zone and graduated transitions between the near, intermediate, and far zones. Still other systems use a distance center in one eye and a near center in the other eye. Knowing how the lenses work can help you select the proper lens for different patients' needs, and better troubleshoot any complaints patients might have once they are in their lenses.
"Most of the education surrounding multifocal lenses covers one type or brand. In a clinical practice, nothing can be further from the truth," Dr. Hom said. "Mixing and matching lenses from different manufacturers is common. Despite what the manufacturer's fitting guides tell you, there is no law stating we must stay within one system or with one type of lens. Any fitter will tell you, we do what works."