PRESCRIBING FOR PRESBYOPIA
A MULTIFOCAL CONTACT LENS DECISION TREE
DOUGLAS P. BENOIT, OD, FAAO
Over the last few columns, I have discussed various aspects of multifocal contact lenses. This month, I will put the pieces together and develop a road map for confident prescribing of multifocal contact lenses. For the purposes of this exercise, the patient is a healthy 45- to 55-year-old who is new to your practice. He is either a successful wearer of single-vision, distance contact lenses or he is new to the contact lens concept. In any case, he wishes to be free of glasses for most of his daily activities.
First, the patient needs a complete eye examination. We need to know the best-corrected vision and the spectacle prescription. We need keratometry or topography, eye dominance, horizontal visible iris diameter, and pupil size in normal, bright, and dim light, plus an assessment of the lids/lashes, conjunctiva, and cornea. If he is currently wearing contact lenses, it would be good to know the lens parameters, care system used, and wearing schedule.
Second, for both wearers and non-wearers, we need to assess the patient’s motivation to wear a multifocal contact lens as well as the patient’s expectations. A discussion of what these lenses can and cannot do is appropriate. The patient’s expectations must be realistic. If he wants perfect vision at all distances, in all circumstances, he may be disappointed. It should be possible to take care of most of his vision needs about 80% of the time.
Next, we get to pick a lens. If the patient has astigmatism greater than 0.75D, an astigmatism-correcting lens may be necessary, particularly if the spherical component is low. We all know that a spherical lens design can mask low amounts of astigmatism in certain circumstances. If the cylinder is corneal, a GP or hybrid lens may be a good choice.
For current lens wearers, look to the lens type that is already being worn. For neophytes, pick the best choice based on collected data and what you are comfortable fitting. From experience, it is not wise to switch happy GP wearers to soft lenses, but new wearers can begin with a GP design.
This patient is a non-wearer and wants contact lenses for social events and outdoor/sporting activities. He has 0.75D of corneal astigmatism and a –4.00D spherical component. The add power is +1.75D. Here, we have a good candidate for a single-use contact lens modality. No care system is needed, so the likelihood of a solution reaction or adverse event from noncompliance is minimized. Most current daily disposable multifocal contact lenses are center-near designs, but there is at least one center-distance design available. All work well in the situation described.
This patient is a current wearer with 0.75D of corneal cylinder and a –2.00D spherical component. The add is +1.50D. He wears monthly replacement soft toric lenses for distance with over-the-counter readers over them. The possibilities include soft toric bifocal/multifocal lenses that can be discarded monthly, quarterly, and annually. Currently, only one monthly lens is on the market. However, dozens of small, independent laboratories produce high-quality, custom designs. Again, be familiar with a few of these offerings so you are comfortable fitting them.
This scenario also lends itself well to a hybrid lens modality. There are currently two designs available: one bifocal and one multifocal. Success rates are high with both iterations.
This patient is obviously also a candidate for a GP multifocal lens. A corneal aspheric design would likely be the best choice, but scleral designs are becoming more popular, and results are great with both.
Easier Than You Think
Multifocal contact lens prescribing is not difficult. It is just different. With a little practice, it can be as easy as fitting single-vision lenses, and it is a lot more interesting. CLS
Dr. Benoit is the senior optometrist with Concord Eye Center, a multi-subspecialty ophthalmology group in Concord, NH. He is a Diplomate of the American Academy of Optometry’s Section on Cornea, Contact Lenses and Refractive Technologies, currently the Special Advisor for the Section. Dr. Benoit is a Distinguished Practitioner and Fellow in the National Academies of Practice-Optometry Section and is a Diplomate of the American Board of Optometry. He is also on the Advisory Board of the GPLI and is the 2016 GPLI Practitioner of the Year. Dr. Benoit is a consultant to, and clinical investigator for, Alcon and Visioneering Technologies.