the contact lens exam

Improve Efficiency With Presbyopic Soft Lens Prescribing

BY GREGORY J. NIXON, OD, FAAO

One definition of efficiency is the production of desired results with minimum waste of time or effort. In today's world of increasing demands and limited resources, methods to gain efficiency permeate all businesses, including contact lens practice. We can define prescribing efficiency in practice as determining a patient's final lens prescription with a minimum number of office visits.

A need for better prescribing efficiency frequently applies with soft multifocal or soft monovision wearers. In spite of the advancements in multifocal lens designs, we know that presbyopic patients' visual benefits often must balance against a degree of visual compromise. When fitting these designs, even a parameter change as small as ±0.25D or one step in add power can have a huge impact on visual clarity. Achieving an appropriate balance of visual function at far, intermediate and near distances can often take several office visits and trials with numerous diagnostic lenses.

Prescribing Strategies

To help achieve this balance of visual function efficiently, always start with a detailed case history to determine how patients use their eyes and what level of visual detail they demand at all distances. Additionally, determination of the dominant eye, mode of correction (multifocal, monovision or modified monovision) and lens design (spherical, aspheric, center-distance, center-near) all have significant effects on patient acceptance of presbyopic correction.

To best judge visual acceptance, it's important to demonstrate the contact lens correction in the office at all viewing distances. I prefer to over-refract with handheld trial lenses to determine the effects of additional plus or minus on visual function. It is advisable to determine the minimal plus power or add effect necessary to achieve functional near vision to minimize any deterioration of distance clarity.

The real determining factor for patient success is how they function in their own visual world. A successful presbyopic contact lens fit is rarely determined by the clarity of the eye chart in the exam room, but rather by the appropriate clarity to drive, read and manage computer-related tasks at work. For that reason, once I establish an appropriate physical lens fit, I often send patients home with multiple trial lenses to test on their own. For example, I may label the blister packs of an initial pair of diagnostic lenses as R1 and L1 and instruct a patient to wear that pair for three-to-five days. I may also send him home with a pair of lenses labeled R2 and L2, which may be +0.25D stronger or in the next higher add power, to wear if he is unable to achieve adequate near vision with the first diagnostic pair. I instruct patients to "wear the winning pair" to their next office visit so I can double check acuity and overall lens performance. Regardless of which pair they wear into the office, I will be one step closer to troubleshooting the lens fit or finalizing the prescription.

Let Patients Decide

Having patients trial various lens powers in between office visits not only improves prescribing efficiency, it also improves fitting success by meeting patients' visual needs where it counts — in their office, not yours. CLS

Dr. Nixon is an associate professor of clinical optometry and the extern coordinator at The Ohio University College of Optometry. He is also in a group private practice in Westerville, Ohio.