Presbyopes in Your Practice

 

PureVision® Multi-Focal Lens Fitting Pearls

- Dr. Paul Karpecki and Dr. Richard Durocher

When fitting lenses, patient selection is critically important since some compromise in vision is almost always a reality. This is true with any multifocal correction, including spectacles. Cylinders above 1.00, especially bilaterally, pose an obstacle to success. If the lens fits too loosely on the eye, when the eyes converge to read, the lens may be prone to decenter, and may do so to the point where the geometric center-near may become decentered. When that happens, the patient is no longer looking through the center-near optics.

It's relatively straightforward to fit early and more mature presbyopes. I generally fit early presbyopes with a low ADD for both eyes. Mature presbyopes often require a high ADD for both eyes - since they need more plus for reading. The challenge is fitting the in-between patients. For them, the low ADD is not enough for reading while the high ADD can be too much. For these patients, I fit a high ADD in both eyes and then neutralize some of the center-near power with minus. For example, if a patient's spectacle prescription is a -3.00 D with a +1.75 ADD I would give them a -3.50 D, high ADD trial lens to start. Then you keep the patient binocular in both eyes without having to resort to a modified monovision or modified multifocal.

Pupil-size evaluation is another important factor to consider when fitting simultaneous vision multifocals. If your patient's pupils do not constrict in bright light and do not dilate in low-light conditions, it's highly unlikely simultaneous vision will be successful. For a center-near lens to work properly, the pupil needs to constrict to eliminate the distance portion of the lens from entering the pupil. Conversely, the pupil must be able to enlarge to allow the distance optics of the lens to enter the pupil as needed. If you don't get normal pupil movement during your preliminary patient evaluation, the individual might be a better candidate for monovision or "modified multifocal."

Modified multifocal requires an evaluation of a particular patient's needs to be most successful. If the patient does a great deal of near work, for example, it is best to increase the plus in the dominant eye. If the patient uses distant vision most of the time, it is beneficial to use the non-dominate eye for maximum near correction.

I've found the level of success also increases significantly if realistic expectations are set before the lenses are inserted, and when refitting patients, remember to compare acuities with the old contact lenses, not glasses.