contact lens focus
Toric multifocal provides customized fit.
Alan P. Levitt, O.D.
If a contact lens practitioner had to name his/her biggest fitting nightmare, many would say “the patient who has astigmatism with presbyopia.” That said, if you can meet these patients' visual and comfort needs, it can be both personally and financially rewarding. I've recently discovered a lens that has enabled me to do this—the C-Vue Advanced HydraVue Toric Multifocal, from Unilens.
Here, I provide an overview of the lens, patient selection, how to achieve an optimum fit and the practice benefits of offering this lens.
The C-Vue Advanced HydraVue Toric Multifocal is a member of the C-Vue Advanced HydraVue family of silicone hydrogel custom contact lenses. (The other members of this family are the Custom Toric, Multifocal and Single Vision lenses.)
The Toric Multifocal can be designed to fit almost every possible combination of prescription and corneal size and shape. Specifically, Unilens allows you to specify the base curve, diameter, power, cylinder, axis, ADD power and zone size of the lens.
The lens is comprised of Contamac's Definitive silicone hydrogel material. The Definitive material provides 74% water content, a Dk of 60 and a low modulus (0.35 MPa). The result: Those patients in whom I've fit the lens report high levels of clarity and comfort.
I've found that the best candidates for this lens meet seven criteria: (1) They are in good ocular health; (2) they have normal binocular vision; (3) they have a refractive astigmatism of between −0.75D and −4.00D; (4) they have ADD requirements of up to +2.00D; (5) they are experienced contact lens wearers (meaning they understand the ins and outs of contact lens wear, and therefore, what to expect in terms of maintenance and care); (6) they already wear toric multifocals, though require enhanced oxygen permeability; and (7) they have realistic expectations, meaning they understand not to expect perfection.
To determine whether I'm dealing with a highly motivated patient, I educate him on what, specifically, he may encounter with overall fit and vision, and I ask him how he feels about this information. For instance, I explain that his night vision should be acceptable, though headlights may produce glare. If the patient says this is unacceptable, he's not a good candidate.
|C-Vue Advanced HydraVue Toric Multifocal|
MATERIAL: Contamac Definitive|
WATER CONTENT: 74%
WEARING SCHEDULE: Daily wear
RECOMMENDED REPLACEMENT SCHEDULE: Monthly
BASE CURVE/DIAMETER: 8.0mm/14.0mm to 9.1mm/15.0mm
PARAMETERS: +20.00D to −20.00D
CYLINDER: Up to −4.00D
AXIS: Any axis in 1°
To achieve the optimum fit with the C-Vue Advanced HydraVue Toric Multifocal, call the Unilens order department (800-446-2020), and provide your patient's prescription and keratometry readings. The representative will then input this information into their computer and calculate initial trial lenses. In addition, Unilens offers helpful fitting calculators for the initial fit and correcting over refraction. These can be accessed at www.unilens.com/calculator.asp.
Once you insert the lens, allow it to equilibrate for 10 minutes. After equilibration, the patient should experience acceptable lens comfort. Now, assess lens movement. The lens should center well with 0.5mm-to-1.0mm movement upon blink in primary gaze. If you note excessive movement, choose a steeper base curve. If there is minimal-to-no movement, choose a flatter base curve. If you note decentration, choose a steeper base curve.
Now, measure the patient's distance and near acuities in normal room illumination, and assess whether lens rotation is stable. If you note inconsistent or excessive rotation, choose a steeper base curve. If the patient's distance visual acuity (VA) is unacceptable, though lens rotation is stable, perform a sphero-cylinder over-refraction employing the minimum minus power to achieve acceptable distance vision. Now, perform a sphero-cylinder over-refraction calculation to determine the correct distance and cylinder powers. (When over refracting, remember that the clearest image may be at any point within the range of lens powers, as you're dealing with a multifocal design.) Also, you can decrease the ADD zone diameter to improve distance VA. (It's not uncommon to have the ADD zone diameter in the dominant eye set 0.1mm smaller than the non-dominant eye, even if pupils are of equal size.)
If the patient's near VA is unacceptable, and rotation is stable and distance acuity acceptable, over-refract to obtain the minimal plus power for acceptable near vision, and add this over-refraction to the ADD power. Also, you can increase the ADD zone diameter to improve near VA. (The patient may experience a greater ADD power effect on the eye vs. the lens. This happens more often with hyperopic vs. myopic patients. Should this occur, over refraction may not work due to the patient's already compromised vision. You'll be able to help these patients if the closest point before their near vision becomes blurry is less than 15 inches. In these cases, you can reduce the ADD power.)
Finally, before the patient departs, instruct him to use a multipurpose solution or wetting drop that contains hyaluronate. This maximizes wetting, and, therefore, lens wear comfort. This, among other fitting information, is included in the C-Vue Advanced HydraVue Toric Multifocal Fitting Guidelines, which you can access at www.unilens.com/pr_ softtorics.asp.
Personally, I've found this guide very helpful, and I feel that anyone experienced in contact lens fitting should have good results with it. That said, a consultant is always accessible regarding complex or unusual cases.
Offering the C-Vue Advanced HydraVue Toric Multifocal has enabled me to meet the needs of a typically hard-to-satisfy patient group. This, in turn, has led to patient loyalty and several referrals. In addition, because the lens is sold directly to independent practices and is not available via online purchase or through retail optical stores, it has also helped to bind patients to my practice. Further, carrying this customizable product has helped differentiate my practice from others and has created a higher sales margin. (In my practice, the contact lens fitting fees increase with the complexity of the fit. So, custom toric multifocal fittings command the highest soft lens professional fees. With this lens, expect at least two follow-up visits after the initial fitting, and factor this extra time into your fitting fees.)
Finally, the C-Vue Advanced HydraVue Toric Multifocal is trial fit with custom-made single lenses. So, once the fit and prescription are finalized post-trial, I order the lens in six-packs for monthly replacements. Specifically, I purchase banks from Unilens to reduce my cost and have less expensive trial lenses. Further, Unilens also allows practitioners who have an active account to order trial lenses at $20 per lens; this amount is credited back to you upon ordering sixpacks. (Lens banks are available for these packs, and this is an additional opportunity to reduce the cost of these six-packs.)
The C-Vue Advanced HydraVue Toric Multifocal has become a part of my contact lens practice because I can customize it according to both prescription and corneal size, Unilens provides one-on-one guidance, if needed, a clear and concise fitting guide, and it's sold exclusively to private practitioners. These characteristics have enabled me to reap both personal and financial rewards. OM
DR. LEVITT HAS BEEN IN PRIVATE FOR ROUGHLY 30 YEARS, WHERE HE HAS OPERATED A SUCCESSFUL PRIMARY CARE AND SPECIALTY CONTACT LENS PRACTICE. E-MAIL HIM AT LEVITTEYECAREMIAMI@GMAIL.COM, OR SEND COMMENTS TO OPTOMETRICMANAGEMENT@GMAIL.COM.
Optometric Management, Issue: October 2011