contact lens business
Making the Most of Torics
Astigmatic patients now have plenty of choices. Here's help making sure they get what they need.

Once upon a time, astigmatic patients who wanted to wear contact lenses had few options. Today, toric contact lens alternatives are proliferating, and with new materials and designs waiting in the wings, the likelihood of a correct, comfortable fit and a happy patient keeps growing.

With that in mind, we asked a number of eyecare professionals to share some pearls from their experience fitting patients with today's toric contact lenses.

Here are two strategies that work well for Jason Jacobs, M.D., who practices in Denver, Colo.:

"Highly myopic astigmats need to have the two meridia vertexed independently to accurately determine the proper prescription," he says. "If you don't do this, you'll get the wrong prescription and start with too much cylinder.

"For example, if the manifest refraction is -9.00 -3.00 x 180, you vertex -9.00 to -8.00, and -12.00 to -10.25. Thus, the proper soft toric prescription is -8.00 -2.25 x 180. Many doctors will just vertex the -9.00 and erroneously prescribe -8.00 -3.00 x 180.

"By getting the optics right, I find I'm more accurate the first time with high myopes. This also reduces chair time.

"Also," he adds, "to minimize chair time, I generally fit torics off the manifest prescription without placing lenses in the office. I stick with toric lenses that, in my experience, fit reliably and predictably -- ones that almost always work out on the first try.

"I've had the best luck with Biomedics torics and CooperVision torics (Frequency 55, Preference and CV Encore). I give the patient trial lenses and have him wear them for a week; then I do a second check for fine-tuning and final ordering.

"Very often, patients are so happy with the trial lenses that they call to skip the follow-up and just order the lenses."

Avoiding Potential Problems

William H. Constad, M.D., of Hudson Eye Physicians and Surgeons in Jersey City, N.J., says there are two astigmatic profiles he doesn't recommend fitting with currently available toric contact lenses:

"Although there are exceptions to this rule, I generally avoid fitting toric contact lenses on eyes that have more cylinder than sphere because the likelihood of success is low. It's important to discuss this limitation with patients before ordering lenses for them.

"I also avoid fitting eyes with mixed corneal and lenticular astigmatism, when the refractive cylinder is oblique," he adds. "In these cases the lens tends to be unstable."

Help From the Web

Mark Andre, F.A.A.O., director of contact lens services for Casey Eye Institute of the Oregon Health Sciences University in Portland, Ore., uses a free software program called "ToriTrack" to help manage and fit toric soft lens patients.

"ToriTrack was developed by CooperVision for use on a computer or a Palm Pilot, and you can download either version directly from CooperVision's Web site (www.CooperVision.com). You can also use the ToriTrack calculator while you're online, or order a free CD containing the software.

"The program helps with the initial design of the toric soft lens and stores the patient's information in the event the lens needs to be redesigned. If necessary, you can enter a sphero-cylinder over-refraction into the computer and it will recommend a power. This system eliminates the errors inherent in estimating lens rotation, and it corrects for lens power as well," he says.

"ToriTrack has a database of parameters for all of CooperVision's toric soft lenses that matches the patient's prescription and topography to the appropriate lens. Additionally, lenses can be ordered online directly using the program." He adds that the Palm Pilot version includes the patient record-keeping function, spectacle to contact lens conversions and a robust cross-cylinder calculation system.

The Best is Yet To Come

According to H. Dwight Cavanagh, M.D., professor and vice chairman of ophthalmology at the University of Texas Southwestern Medical Center in Dallas, toric contact lenses have been problematic for his patients.

"The primary reason is that the current materials in widespread use have low oxygen transmission levels. For example, several major brands only have an oxygen permeability of 24. This problem is exacerbated by toric designs, which require thicker edges. Taking materials that have barely enough oxygen permeability and making the edges thicker creates hypoxic problems.

"The ideal solution," he says, "is to make the lenses out of the new hyperoxygen permeable materials, with Dk's as high as 175. Unfortunately, this hasn't happened yet, although such lenses may be available by this fall. These materials should lead to breakthrough toric designs because without the hypoxia problem you'll be able to change edge designs and geometry in ways not previously possible.

"I believe that many more patients will switch to these lenses once they become available in the new materials. For patients who aren't currently successful, this will be a whole new ball game with new materials and new designs. Patients who are successful with current lenses should love these even more.

"In the meantime, patients who have trouble wearing current torics will just have to cut back on wearing time and wait for the newer ones to become available."