Monovision vs. Multifocal Contact Lens Designs

BY William B. Hutcheson, O.D., & Denise L. Paquin, O.D.
Nov. 1997

The demand for correcting presbyopia with contact lenses has never been higher. To be successful in providing this service, it's critical to understand how to best match lens designs with patient needs. In working with patients over the years, we've often been struck by the disparity between what the patient experiences and what the practitioner is able to measure and observe. Lacking the often-wished-for ability to see through the patient's eyes, we felt the best way to close that communication gap would be for the doctor to become the patient.

Here we present a practitioner's first-hand evaluation of each of three types of RGP contact lens correction for presbyopia.

In this study, with Dr. Hutcheson sitting in the patient's chair, we investigated the practical results achieved with each of three different RGP contact lens approaches to dealing with presbyopia. We assumed that an optimal physical fit was achieved, and we concentrated our assessment on how well each design met the visual needs of the patient.

METHODS

We present a comparison of monovision, a translating segmented bifocal design and a translating progressive addition design. We did not evaluate aspheric simultaneous vision designs because in our experience, the lenses of that type are inherently limited in add power and best suited for emerging presbyopes only.

For the translating RGPs, we used TruForm's Solitaire II segmented bifocal and Llevations progressive addition designs. For the monovision approach, we used a single vision Starlens design from X-Cel. We selected these lenses because they are representative of their types and the manufacturers have excellent teams of consultants and guaranteed fit warranties.

Dr. Hutcheson wore each pair of lenses for an adaptation period, during which time Dr. Paquin evaluated the fit and modified the lenses to achieve optimal comfort, acuity and physiological performance. Tables 1 and 2 list the raw data and final contact lens parameters. Dr. Hutcheson then wore each final pair of lenses for one week in succession, repeating each three-week cycle three times. We evaluated the visual performance of each modality via in-office measurements and through Dr. Hutcheson's detailed observations in a variety of situations. The objective and subjective results are detailed in Tables 3 and 4.

THE PATIENT'S PERSPECTIVE

While monovision scored well in the OU objective visual acuity measurements, it received the worst subjective marks overall. This confirms our clinical observations that most monovision patients, while preferring monovision to wearing reading glasses, are not totally satisfied with their vision. It is unquestionably a compromise situation, especially with night driving. Surprisingly, despite the measurably reduced stereoacuity with monovision, the greatest annoyance with driving at night was not so much loss of clarity or degraded distance judgments, but rather the flare around lights caused by one in-focus and one out-of-focus eye. Compared to previous experience with distance-only contact lenses, night-time flare was also the biggest compromise experienced with both translating designs, as the larger pupil size allowed more light to pass through the near segments. This effect was almost negligible with the bifocal design (Solitaire II) and more noticeable with the higher seg height progressive design (Llevations), but it was to a far lesser degree than that experienced with monovision.

A well-positioned bifocal seemed to provide the best acuity and visual comfort for both straight-ahead distance viewing and desktop-level close work. The translating progressive design measured about as well objectively in these two situations, but the subjective quality of vision was not quite as good. However, when doing a significant amount of mid-range computer work, the Llevations worked noticeably better than the Solitaire II. When close work is at eye level or above (a workstation with a high monitor, charts mounted on a wall, etc.), monovision is the superior option.

UNDERSTAND YOUR PATIENTS' VISUAL NEEDS

Monovision is inexpensive and easy, and it works reasonably well for a lot of patients, especially in the earlier stages of presbyopia. However, for patients who need maximum acuity at distance and near, a two-focus translating design like the Solitaire II should be your starting point. Add in a computer or other intermediate demand, and a multifocal design like the Llevations makes the most sense.

The most successful dispensers of spectacle eyewear have learned the importance of understanding their patients' visual needs in order to guide them to the lens options most suited to meeting those needs. Contact lens practitioners must similarly take the time to understand patients' visual demands and to educate them about the options available to them, including translating designs which may provide better overall quality of vision.

If you are presbyopic, consider having a colleague fit you with multifocal contact lenses. The number of patients interested in trying these lenses increases dramatically when they know their doctor is wearing them. Also, the practical tips you will be able to pass on to your patients will be invaluable.

Obviously, no one design can satisfy every patient. Know your patients and make use of the many fine lens options available. CLS

Drs. Hutcheson and Paquin have no financial interest in any of the companies mentioned.

Dr. Hutcheson is in private practice in Herndon, Va., with a strong emphasis on contact lenses. He is an AOA Contact Lens Section member and has been a clinical investigator for several contact lens designs. Dr. Paquin practices in Manassas, Va., and is a charter member of the AOA Contact Lens Section.