Multifocals
Meeting the Multifocal Challenge 
Experts answer common questions about multifocal lenses.
By Terri B. Goshko,  Senior Associate Editor

Is the task of fitting multifocal contact lenses challenging to you? Are you feeling confident about how to choose the best multifocal lens for your patients?

This month, we'll give you some fitting and problem-solving tips from experts, as well as other timely information that you may find helpful for this aspect of your practice.

The following is good advice from two well-known contact lens experts.

• Mary Jo Stiegemeier, O.D., F.A.A.O.,
• Loretta Szczotka, O.D., F.A.A.O.

QUESTION: When are soft multifocals more appropriate than rigid gas permeable (RGP) lenses?

Dr. Stiegemeier: If the refractive cylinder is less than 1.00D, or the spherical component is at least three times the cylindrical component, I'll try a soft multifocal. If the refractive cylinder is moderate to high, I'll try an RGP multifocal lens.

I tend to fit patients in multifocals in the same type lens they wore before their multifocal fit. One exception is patients wearing soft torics -- I'll try to switch them into RGP multifocals. If they can't tolerate them, or have had a prior negative impression of rigid lenses, I'll fit some of the new toric multifocals that have worked very well.

Dr. Szczotka: Soft lenses are appropriate only if the patient is a candidate for nontoric distance soft contact lenses (i.e., low astigmatism, previous soft lens wearer). If the patient's a candidate for either soft or RGP lenses, soft lenses are favored over RGPs for those who desire only part-time or social contact lens wear because RGP adaptation isn't an issue then.

Some new, nondisposable specialty toric soft multifocal lenses available would be suitable for patients who're RGP intolerant or have lenticular astigmatism necessitating a soft toric lens for vision correction, with a built-in aspheric multifocal. Consider these lenses for specialty cases when you've ruled out a standard soft multifocal or RGP lens.

Most of my bifocal contact lens fits are with RGP multifocal lenses. They have the advantage of allowing full correction of corneal astigmatism, and variable back surface eccentricities which allow various add powers. Any person who has been wearing RGP lenses or any new presbyope who's an RGP candidate and wants to wear contact lenses for most of the time is a good candidate for RGP multifocal lenses.

I usually use simultaneous back surface aspheric designs, but an alternating/translating design is also available. This design has higher add powers for the mature presbyope, but has no intermediate range of focus and may have variable vision if the add segment moves into the visual axis with each blink. Trifocal segmented designs exist, but I haven't found them to work.

QUESTION: Do you need to have trial fitting sets?

Dr. Stiegemeier: They're essential for all soft lens multifocal fits and most RGP multifocal fits. They're not only helpful for final lens parameters, but they can help you weed out patients who can't cortically adapt. They also help you capture patients while their enthusiasm is at its peak. "Show, then tell" works well with trial lenses; I believe much of my success with soft multifocals is due to trial sets.

You can fit RGP multifocals without trial lenses, but it's helpful to have them, especially when fitting translating rigid multifocals. I like to demonstrate to the patient how the lens will feel, and what type of vision he can expect. I also like to evaluate the lens on the eye to check fluorescein patterns and bifocal height. I recommend that you try several types of simultaneous and translating RGPs and then invest in fitting sets of the types you're most successful with.

Dr. Szczotka: You should fit all soft lens multifocals from trial lens sets -- that's the beauty of the new disposable lens systems. The fitting sets allow on-site fitting and problem solving. Remember, fitting these patients is both an art and a science. Often, we have to find the best compromise that fits a patient's lifestyle, and there isn't one lens per patient that we can extract from a manufacturer's nomogram.

However, I have increasingly good success rates using empirical RGP lens ordering based on topography or keratometry plus manifest refraction. Although fitting from a diagnostic lens set will ultimately give you the best success rate, I don't hesitate to try empirical ordering, knowing that a lens is warranted for exchange and that my patient understands that a reorder may sometimes be necessary.

QUESTION: Do you think that there's a role for modified monovision with multifocals?

Dr. Stiegemeier: Yes, when performed with the appropriate lens design. Multifocals should give good vision for at least two focal points binocularly. In early presbyopia, or for patients who require excellent distance acuity, a bifocal lens (usually on the nondominant eye) with a single vision distance lens (usually on the dominant eye) works. Patients needing excellent near acuity may combine a bifocal lens (on the dominant eye) with a single vision near lens (on the nondominant eye).

There's also a "Modified Bifocal Approach" where two bifocal lenses are used -- one lens (on the dominant eye) is set for distance acuity and the other lens (on the nondominant eye) is set for intermediate and near.

Some soft lens designs are made to use this technique as a complementary system. You can use some -- but not all -- disposables this way. This technique also works with RGP designs. Demonstrate the technique by using a loose plus trial lens over one eye to see whether "weighting" the prescription on one eye significantly improves or hampers vision. It's also a useful trial that can help tell you whether the patient can adapt.

Dr. Szczotka: Yes, I think there's a role for monovision with bifocals, especially for simultaneous progressive soft or RGP lenses when near vision is compromised and/or additional add power isn't an option.

For example, increased add power may not be available (the manufacturer may not offer it, or the increased add power may sometimes diminish your patient's distance vision).

I tell the patient she's still wearing bifocals but that one lens (usually on the dominant eye) will cover distance and intermediate vision and the other lens will cover intermediate and near. It works for many patients.

Although I don't recommend it as the primary fitting option, I sometimes end with it. In a successful patient, the nondominant eye (near) still has at least 20/40 distance vision and 20/20 near.

QUESTION: Which lenses are best for which situations (e.g., cosmetic use, computers, etc.)?

Dr. Stiegemeier: For patients who need outstanding acuity both distance and near and wear or have worn RGPs, I opt for the RGP translating designs. If the patient currently wears RGP lenses, is an early presbyope, 

has a lower lid lower than the inferior limbus, or has intermediate vision needs, I'll opt for an RGP simultaneous vision design.

If the patient is intolerant of RGPs or has worn soft lenses, I start with a simultaneous design soft disposable lens. For all new patients who require a multifocal design and can wear soft lenses, I begin with soft disposable multifocals. I also use soft disposable multifocals for patients who require excellent intermediate acuity, such as those who work on computers. Disposable multifocals are also my choice for patients who want flexibility, such as part-time or extended wear.

Dr. Szczotka: First, you need to have a general knowledge of a prescribed lens's design. If the patient requires any intermediate vision (most do, for computer use or car dashboard, for example), a progressive or simultaneous contact lens is best. Most concentric simultaneous lenses are divided into either a center-distance or a near-distance design, which refers to the optics in the lens center.

Most RGP bifocals are center distance and have a progressive shift to more plus power in the lens periphery. A center distance lens is best suited for patients who need excellent distance vision under bright or average light. The patient will have better near vision when her pupils are larger. Therefore, the center distance lenses will work if, for example, a woman wants to wear them to read a menu in a dimly lit restaurant. RGP center distance lenses also have mild lens translation in downgaze, which can enhance near vision under all lighting conditions.

Soft lenses are available as center distance or center near. Center near works best for patients who need excellent near vision under bright light (such as in brightly lit offices). When the patient's pupil constricts, near vision is enhanced and distance vision is diminished. Distance vision improves under dim light as the pupil dilates and the distance optics enter the visual axis.

Concentric simultaneous soft lenses with alternating optics are also available. They're pupil independent; therefore, changes in room illumination are less of a concern with them.

Another form of modified monovision with soft lenses is to use a center-distance lens on one eye (usually the dominant eye) and a center-near lens on the other eye. This gives monocularly enhanced vision at a particular distance while preserving binocularity. It works well for those previous monovision patients who want to upgrade to bifocals. 

Dr. Stiegemeier is in private practice in Beachwood, Ohio. Dr. Szczotka is an assistant professor at Case Western Reserve University Department of Ophthalmology and director of the contact lens service at University Hospitals of Cleveland in Ohio.