prescribing for presbyopia
Prepare the New Presbyope for the Future
BY DAVID W. HANSEN, OD, FAAO
The "Age of Denial" has passed. Your presbyopic patients have finally admitted their vision isn't getting any better. They have tried the pharmacy "cheaters," enlarged the font size on their computers, and increased the lighting. What do we recommend?
Be the Doctor
Patients will tell you anything to avoid "going into a bifocal." They think it is a dreaded disease, and I believe some practitioners have encouraged this attitude by saying bifocal contact lenses don't work, that RGP bifocals hurt or are really expensive. Once the patient has confessed his or her plight, it is time to "be the doctor" and advise the best options.
If RGP lenses hurt, contact the laboratory. Lenses with poor edges do hurt. Solve this problem with better manufacturing. If the perception (both patient and doctor) is that bifocal contact lenses are expensive, you must believe and explain that multifocal contact lenses are an investment that provides consistent, quality, natural vision with durable devices. It truly is the least expensive option for presbyopes tell them so!
Where to Start
If there are no presenting challenges such as ptosis, lid flaccidity or higher reading needs, try a posterior aspheric design fit either close to K or slightly steeper than K. These thin, acceptable designs are similar for emerging presbyopes pre-adapted to RGPs, comfortable for those who have never worn contact lenses or are presently wearing soft designs. Why RGPs? Now is the time to prepare the patient for the future.
As most of us know, soft bifocal designs presently have more compromise for latent presbyopic needs. RGP designs will be easier to fit when higher adds are needed. Aspheric and concentric designs also help the intermediate needs of those using computers.
Don't be discouraged with potential residual or high astigmatism for the presbyope. You can use concentric and decentered DeCarle designs for these patients. These designs start with the same philosophy utilized with single vision options. Fit patients with residual astigmatism with front toric designs, and fit patients with over 2.50D of corneal toricity with bitoric construction. Aspheric options may mask small to moderate (0.75D 3.00D) astigmatism and alleviate the need for a prism ballast toric design. Diagnostic lenses will aid the decision.
Laboratories have carefully calculated most of the lens parameters for certain situations. Their consultants will gladly assist with suggestions. The typical aspheric multifocal design has a 9.2mm diameter with modifications for larger or smaller VIDs. Decentered DeCarle lenses are usually 9.3mm with a 0.3mm truncation, and concentric designs can range from 9.0mm to 9.8mm. Translating bifocals can be round or designed with truncation option.
I recommend fluorescein observation with slit and Burton lamps to finalize the fit. High magnification helps determine the nuances needed for success.
Benjamin Franklin said in Poor Richard's Almanac in 1745, "Drive thy business, or it will drive thee." Take charge and start the emerging presbyope with RGP multifocals.
Proper aspheric multifocal alignment.
Dr. Hansen, a diplomate and fellow of the American Academy of Optometry, is in private practice in Des Moines, Iowa.