Street Smarts

Maximum Plus = Maximum Remakes

By Dan Beck, OD Leland, N.C.

One of the hallmark rules of refracting that every optometry student learns during the first week of school is to “push plus.” Give the patient the most plus they can handle during the exam. The only problem is that, in the real world, it’s just plain wrong.

This concept is taught so the patient won’t be over-minused. As we all know, giving someone too much minus power can lead to strain and discomfort, especially during near-vision activities. What further complicates this is that over-minusing by a few steps usually doesn’t blur the letter chart for most patients. Unless strong cycloplegics are used before the refraction, which is rare unless the patient is a young child, patients will usually accommodate through the extra minus.

The idea of maximum plus also assumes the patient’s level of accommodation is constant whenever that patient happens to be refracted. Tired or strained eyes may accept more plus or may be in some degree of spasm, which leads to a desire for more minus. If a particular patient is tired and takes more plus, he may experience blurry vision when his accommodation is fresh. Too much plus at distance can’t be accommodated for, while too much minus can be.

Patients come into our offices wearing over-minused glasses and contact lenses all the time. We refract them and find several steps more plus. Any optometrist who has been practicing for a while knows full well we can’t take that extra minus away from these people. Their accommodative systems are accustomed to overworking. They’ll hate anything you prescribe them that’s more than a step or more plus. They’ll hate it and you’ll be remaking those eyeglasses or reordering those contact lenses.

Progressive lenses also make too much plus a nightmare. Considering how a progressive lens works, patients can get a little extra plus with just a slight head tilt. Older hyperopic patients often handle much more plus than their current eyeglass prescription during a refraction, yet they have no distance complaints. These patients are looking through the lens area where the progression starts instead of the distance portion. They usually complain more of near vision blur because they’re using up some of their intermediate power for long viewing. When you fully correct the distance hyperopia, the patient will, in effect, have too much plus every time he tilts his head, and remember — he’s used to tilting his head!

While the concept of pushing plus is correct in theory, it simply doesn’t work in the real world. None of us wants to give our patients too much minus power if it’s not needed, but the fact is, they do need it. They need it because they’re used to it. What we find during refraction and what the patient needs aren’t always the same thing. Keep this in mind to avoid remakes and unhappy patients. nOD