Take Some Frustration Out of Multifocal Fitting
One practitioner shares tips that have improved his success rate with multifocal contact lens patients.
By Larry Wan, OD
Eyecare practitioners who don't specialize in presbyopic contact lens fittings or see many presbyopic cases each week may think that fitting multifocal contact lenses is a frustrating task. Presbyopic contact lens fittings are great for building and maintaining a practice, but the early fitting process can present tricky obstacles. One or two negative presbyopic fitting experiences in a short period of time can create the impression that multifocal lenses simply don't work.
But why do some practitioners report an 85 percent success rate with multifocal contact lenses while other doctors claim only 25 percent? Maybe there's more to this puzzle than we thought. In fact, we have great potential to successfully fit the majority of our presbyopic patients -- but we need to take a step back and assess the particular challenge of multifocal contact lenses. The right tools and a few fitting tips up our sleeves can help us achieve fitting success and fulfill our mission of helping as many patients succeed as possible.
As a peer "in the trenches," I'll offer a few pearls of wisdom and try to point out a few things that may help increase your fitting success with multifocal contact lenses, which represent a promising new option. First, let's talk technology.
The Lens Makes the Difference
I've achieved great success with CooperVision's Frequency 55 Multifocal. This modified monovision system is actually designed to accommodate separate dominant (D) and non-dominant (N) eye prescriptions. Few other multifocal designs feature a modified monovision system, especially in a disposable lens.
The Frequency 55 Multifocal lens also features spherical correction and aspheric correction zones. These overlapping designs can help correct intermediate areas of depth and focus. This allows us to offer our patients a better range of focus, not just near and distance vision.
Figure 1. Use flipper lenses while the patient reads a magazine to fine-tune near
Fit Based on Patient Needs
Prepare yourself and your patients to spend extra time to achieve the best possible multifocal contact lens fit. Explain the difference between near and distance vision and how multifocal contact lenses work to correct the full range of vision. Ask your patients about their lifestyles and careers to help you determine where to place the emphasis on the initial correction.
For example, for an engineer, architect or writer, I know that reading and other near-vision tasks are most important to that patient's daily comfort. For patients such as these, I put an initial emphasis on getting the best possible near vision, but I provide an explanation to manage their expectations. I might tell them, "Your distance vision will be functional but not perfect because our first priority is to get your near vision as clear as possible. Let the lenses adjust for a few days, then we can fine-tune the correction. Once we've got good near vision we can tackle the distance vision in a second visit." A preemptive discussion such as this with patients can help prevent later frustrations.
I hold different conversations with very active individuals. For example, I might say, "I don't want to compromise your active lifestyle, so let's optimize your distance vision and also provide you with functional near vision. I still have room to improve your reading vision if needed at your next progress evaluation."
Be sure to manage your patient's expectations throughout the entire experience. New technologies and improved techniques may provide your patients with a degree of freedom they haven't experienced in years. Of course every patient wants perfect vision. While perfection may not be possible for every patient, we can certainly deliver functional near and distance vision together with comfort and convenience that other correction methods can't touch.
Listen to Your Patients
Paying attention to small details will give you the understanding and ammunition to fit most of your patients successfully. Before you even begin a multifocal contact lens fitting, you should determine if the patient has realistic expectations and what his specific needs are. For example, a patient may say, "I have trouble reading." Does this mean:
- He has difficulty reading newspaper print at a distance of 40cm?
- He has difficulty reading small print such as stock quotes?
- He has difficulty reading highway signs at nighttime?
Ask probing questions such as, "When do you notice that you have trouble reading?" Specific open-ended questions will reveal critical information to help you make a better first lens selection. Expect high multifocal fitting success if you discover that your patient is:
- Uncomfortable with monovision
- Experiencing inadequate computer vision with his multifocal eyeglasses
- Unhappy about always looking for his reading eyeglasses
- An emerging presbyope who doesn't want reading or multifocal eyeglasses
- Not satisfied with previous multifocal contact lens trials
When your presbyopic patients return for followup, ask a simple question to help you gauge how your patient is seeing such as, "What do you like about your vision with your new contact lenses?" Then listen...really listen. Your patients will tell you the clues you need to take their vision to the next level.
Fitting Dominant and Non-dominant Eyes
Before you even put the first lens on a patient, determine which eye is dominant. This tidbit of information provides an excellent gateway to describe to your patients how multifocal contact lenses work.
Explain to patients that their dominant eye is like a computer that's faster and quicker than the non-dominant eye. The brain picks up and processes information that enters the dominant eye faster and easier. The non-dominant eye picks up the same information, but it gets to the brain just a fraction slower -- similar to a slower computer.
This analogy works well because you can explain to patients why they're right-eye dominant or left-eye dominant as well as why they're right handed or left handed. Their dominance results because the dominant side is bigger and faster and therefore easier for the brain to use and control.
In most cases, correct the dominant eye for distance vision (patients tend to notice blurred distance vision more readily in this eye) and bias the non-dominant eye for near vision. You may occasionally encounter individuals who can tolerate only near vision or both distance and near vision in their dominant eye. Understanding eye dominance will help you customize your patients' vision.
Another helpful hint is to assess vision with both of the patient's eyes open and not covered. Don't test each eye individually. Remember, these lenses "trick" the brain into working with a dominant eye. If you correct the non-dominant eye while occluding the dominant eye, you won't get an accurate assessment of the dominant eye's influence. The reverse is also true, so always test and adjust binocularly.
Simplify your Multifocal Fitting Routine
Practitioners often make the mistake of changing several variables at one time when fitting multifocal contact lenses. This makes it difficult to determine which specific change actually helped or hindered the outcome. By the nature of simultaneous vision contact lenses, the patient will experience a subtle, low-level, double-like vision. Simultaneous vision multifocal contact lenses create a near-vision focus and a distance-vision focus in each eye.
With the Frequency 55 Multifocal lens system, the D lens enhances the distance image and the N lens enhances the near image. The patient's brain must learn to adapt by filtering out the secondary, or dimmer, image.
Because of this adaptation lag time, patients may find it difficult to make the correct judgment or give you valid information if you test too many trial lenses at the first fitting session. Once you achieve functional distance and near vision, give the patient about four days to seven days to adapt. The initial fitting session is a starting point for patients to evaluate how the lenses will work for their day-to-day lifestyle. Expect to make adjustments in 20 percent to 40 percent of your first follow-up visits. It's worth it to schedule these visits because proper adjustments can increase your fitting success up to 80 percent.
Consider Adjusting Spherical Power First
Simultaneous vision multifocal contact lenses create a dual or double-like visual experience. Patients interpret this experience as "blurred vision," so it's important to educate patients about what they're seeing. Use key terms such as shadowing or ghost image to help patients understand the adaptation process. They will adapt and naturally select the more dominant image.
For most multifocal designs, this ghosting or shadowing becomes more distinct and bothersome as add power increases. For this reason, try selecting the lowest possible add that will get the job done. Starting this way will help the adaptation process by minimizing the simultaneous vision phenomena. Similarly, your success may increase if you first adjust the spherical power to improve the distance or near vision, then adjust the add power to further improve near vision.
Make Real-life Vision the Goal
Don't waste your time or set yourself up for failure by getting too caught up in testing details. Immediately after you place your initial trial lenses on the patient, send him out of your examination room and ask him to take a short stroll into your optical or reception area to allow the lenses to settle. Let his real-world experience help dictate your next move.
When the patient returns to the exam room, simply ask, "How is your vision?" Use the 20/25 line of your chart as the smallest line to quantify his vision. Don't set your patient up for failure by using a 20/20 line or 20/15 line. You can assess the patient's quality of vision by how easily he reads the 20/25 line. If he rattles off the 20/25 line without hesitation, you could probably extrapolate that he can see 20/20. If he struggles to read the 20/25 line, you can speculate that his acuity may be 20/30 or worse. Along the same thinking, use a magazine to gauge his reading acuity (Figure 1) instead of a reduced Snellen chart. A reduced Snellen chart emphasizes what he can't read, whereas magazine print shows him what he can. Look at the big picture -- strive to achieve functional and acceptable distance and near vision.
It's Worth Trying
Fitting multifocal contact lenses is among the more challenging projects that practitioners come across -- but many of us enjoy a good challenge now and then. Try a few of these tips, and hopefully you'll be pleasantly surprised at your improved success rate. New technologies such as the Frequency 55 Multifocal lens system raise the bar and offer us a stronger starting point. You may find yourself fitting your presbyopes like a pro in no time.
Dr. Wan is a managing partner of a multi-practitioner eyecare practice in Campbell, CA. He consults for several contact lens companies including CooperVision.