Features: Contact Lenses

Sep
2003

Solving the Mystery of Torics

By Karlen Cole

Fitting and dispensing today’s toric contact lenses

“Can contact lenses ever challenge spectacles? We think so.” So said Brien Holden, Ph.D., from the University of New South Wales and The Cooperative Center for Eye Research and Technology in Sidney, Australia, at a seminar at the Contact Lens and Eyecare Symposium earlier this year. “In two to five years, the conventional contact lenses that you have in your office now will no longer be there,” she told eyecare practitioners.

Dr. Holden may well have been talking about the new crop of toric CLs. Designed to be more comfortable for patients and easier to fit for practitioners, both oxygen-permeable (GP) and soft toric contacts may be the magic wand that will provide crisp near-vision to over half of vision-corrected consumers. That’s an impressive body of overlooked high astigmats who have been told they can’t wear CLs, or low-power astigmats whose degree of astigmatism didn’t warrant toric corrective lenses.

The New Toric Market: Mid-to-low Power Astigmats
“When I was struggling to fit truncated soft toric lenses over 20 years ago, I often dreamed of a day when soft torics would be easy to fit and well accepted by my astigmatic patients. Some dreams really do come true,” exclaims Patrick Goughary, a contact-lens instructor in the Ophthalmic Science Department at Camden County College in Blackwood, N.J. “Manufacturer’s made improvements to soft torics year-by-year, ultimately providing a great service to contact-lens fitters and patients alike. Companies are confident enough in their torics to offer guaranteed success. They also supply calculators, software and online help to solve the complex power problems that result when over-refracting lenses rotate, as torics do.”

The latest toric contacts are just as comfortable as their single-vision counterparts. Most toric designs now include some form of controlled lens thickness and comfort-edge technology for greater wearing comfort. They are also available in an impressive array of materials, dimensions and powers. Major brands of soft toric CLs claim a wide variety of parameters with comfort akin to a spherical CL.

Visual comfort and wearing comfort are what patients are looking for in a contact lens. Many mid-power (1.75 to 3.50 D) astigmatic patients were advised in the past that they could not wear contact lenses and low-power astigmats (0.75 to 1.50 D) were told toric CLs were not necessary because of their low amount of astigmatism. Now, patients exhibiting -0.75 diopters or more of residual astigmatism can be successful with toric contact lenses, which often provide crisper vision than they’ve ever had before.

“With so many new soft toric lenses available, we’re able to fit new and current lens wearers with greater comfort and better visual acuity than ever before,” says Sandra Shannon, optician/owner of Classic Eyes Optical in Ocala, Fla. “Even lower power astigmats are being fitted with torics instead of spherical equivalents, with much better acuity and fewer complaints about fluctuating vision.”

Due to recent evolutions in research and development, manufacturing technology and improved lens materials, toric lens quality has improved dramatically. 

 “Today’s toric contact lenses, both soft and oxygen permeable, are far better quality than years ago, with better reproducibility,” notes Joseph Bitonte, optician/owner of Bitonte Contact Lens Service in Columbus, Ohio. “I like fitting GP torics, because I find that the visual acuity is generally better. GP lenses today are easier to fit and far easier for the patient to adapt to wearing than a few years ago. They only take a day or two to adjust to, versus a month or two like before. Most practitioners are fitting toric soft contact lenses because it is perceived as easier to do, with more profit margin. In reality, oxygen-permeable CLs can be just as easy to fit plus more cost-effective, because there is better patient retention… patients can’t shop out GP lenses like they can most soft lenses.”

ECPs can fit toric lenses right out of the gate to a new patient with virtually any degree of astigmatism. They can also address torics as an upgrade to all their previous low-astigmat, spherical contact-lens-wearing patients—a clear practice builder.

A suggested script to address current low-power astigmatic spherical CL wearers is: “I’ll upgrade you and put you in a new product that will give you better vision.” It’s simple, precise and who could argue with that (who wants less than the best vision)? The practitioner will gain better professional fees and the patient will gain optimum CL vision, a win-win situation.

The toric lens market now includes not only GP and soft standard disposable lenses, but also daily disposable, progressive and cosmetic toric lenses as well. These new options give practitioners the ability to fit their patients in one spherical and one toric CL in the same brand.

Fitting Torics: It’s Not as Hard as You Think
“With today’s time restraints, competition and lean profit margins, first hit success is mandatory for a healthy eyecare practice,” notes Stephen Byrnes, OD, a private practitioner in Londonderry, N.H.

Consistency and stability are key when accessing lens rotation on a soft or GP contact lens. Compensation for lens rotation can be calculated by using the tried-and-true method of LARS: Left Add, Right Subtract. Utilize lenses from a trial lens fitting set. Trail-fit the lens closest to the cylinder power and axis as possible, allowing the trial lens to settle for at least 15 minutes prior to evaluating rotation. Then observe which way the lens rotates on your patient’s eye, left or right. The next step is to add or subtract according to the LARS method by noting how the scribe marks on the lens fall. Finally, adjust the contact-lens cylinder axis to compensate for the exhibited CL rotation. Then order the lens.

The lens should always relocate to the same position, or less than 10 degrees on a blink. Assess the scribe marks at five, six and seven o’clock; each hour represents 30-degrees. If necessary, over-refract with a sphere or sphero-cylinder to maximum visual acuity.

“Always be stingy on the cylinder correction,” advises Dr. Byrnes. “Round down, not up when choosing the amount of cylinder in the lens. For example, if the patient requires a -1.50 cylinder but -1.25 and -1.75 are the only available cylinder powers, I use a -1.25, not a -1.75. The reason is that minus rotation is less noticeable in the lower cylinder power. Patients can tolerate up to -0.75 residual astigmatism.”

Many toric CLs are prism-ballasted, meaning the base rotation (thickest part of the lens) and orientation marks are at the six o’ clock position. Some toric CLs, such as the Acuvue Toric, feature lenticulation/thin zone toricity, with orientation marks at the three and nine o’clock position. It’s important to know each type and brand of lens you are working with and know where the scribe marks are located.

The current crop of toric CLs can be ordered empirically or based on refraction and keratometry readings alone. Becoming proficient in empirical evaluations and ordering can save chair time for both the patient and the practitioner. ECPs can look to their CL companies of choice for training assistance and refresher courses in toric contacts.

“If the trial lens is close to the patients Rx, I dispense the lens and allow the patient to wear the lens for several weeks,” says Dr. Byrnes. “On the return visit, I recheck the lens rotation and over-refraction and make necessary adjustments.”

All indications are that the toric CL market will advance farther and faster in the near future. Now that CL manufacturers have identified a large group of previously unsatisfied astigmatic contact lens wearers and potential wearers, more toric CL product rollouts are all but certain. If practitioners choose to embrace torics as the first-time lens recommendation to the majority of their astigmatic patients—and as their contact-lens upgrade of choice—they will drive the market to satisfy the consumer need for comfortable contacts that provide the sharp vision these patients always wanted.
Toric Tools: What You Should Have On-Hand
Both soft and oxygen-permeable (GP) trial lens fitting sets. Now that soft
disposable CLs come in flat-packs, it is not necessary to disinfect and store soft CLs for re-use. Just try and toss.

Fitting charts and methods. These are available in print and also on compact disc from major CL manufacturers like CIBA Vision and CooperVision. The CD format can do your toric CL fitting calculations for you.

Brochures, handouts, mailers and other toric CL patient-directed media. Be sure to have information readily visible and available at every station in your office, from the reception area to the pre-test area to the exam room and dispensary.

A well-trained staff. The message about toric CLs should start at the reception desk, to pre-test, to the exam room, to the CL technician and optician. The doctor’s powerful recommendation to the patient will then be a matter of course, rather than a long explanation to the patient. A CL technician well-trained in toric protocol, primarily fitting and dispensing torics, can help save time and retain patients with savvy patient training and troubleshooting.

Utilize the power of the ’Net. Contact-lens manufacturer web sites provide toric information and tools plus links to other informative sites. Awareness of all the brand names and companies marketing toric CLs today may be the greatest tool of all. Keeping track of toric CL developments and parameters helps keep you in the loop so when new products come out, you and your patients are ready to embrace it.

Keep the right solutions on-hand. Be sure to teach patients the correct handling techniques and care and maintenance of their toric contact lenses, emphasizing that torics are specialty lenses that will perform better with special care.

Fitting tools—such as toric calculators, software and online sources that help mathematically compute toric CL fitting parameters

 

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