2006 Contact Lens Update
GP Industry Update
New designs and treatments enhance comfort and expand the options for your patients.
BARBARA ANAN KOGAN, O.D., Washington, D.C.

GP lenses may not be the hot topic in contact lenses at the moment, but they do garner between 10 and 13% of the U.S. contact lens market. And GP patients are seven times as likely to return to your office for follow-up. New GP lens designs offer more options for mature presbyopes, pellucid marginal degeneration, keratoconus, irregular astigmatism, corneal reshaping and more.

Here we'll explain the benefits of the latest FDA-approved designs. Manufacturers also offer new fitting guides and diagnostic fitting sets to address previous visual, ocular health and comfort problems. Some improvements include the ability to successfully fit presbyopes who require higher adds and work with corneal irregularities

EU*

JAPAN

9%

2%

7%

10%

2%

18%

109%

113%

N/A

-7%

-10%

13%

13%

5%

7%

-21%

-12%

-19%

-0.6%

-3%

-3%

More for the mature presbyope

While GPs must compete with soft lens options for many conditions, presbyopia is one area that still holds the potential for GP market growth. "This is the largest segment of the population," says Mike Johnson, director of consultation at Art Optical. "It's the last frontier for GPs." Multifocal GP sales saw a 20% increase last year. Lee Dickerson, president of ABBA Optical and immediate past president of the Contact Lens Manufacturers Association (CLMA), believes this is due in part to the development of new lens designs. "Many practitioners are now leaning away from prescribing monovision now that we have developed good multifocal and bifocal lenses," he says.

New designs offer mature presbyopes more add power, without sacrificing comfort. Many of today's multifocal lenses have large distance and intermediate zone diameters to provide sufficient movement.

Some multifocals add more power to the front surface. This allows you to adjust a presbyope's prescription without the need to switch to another lens. "Because presbyopia progresses with time, it often means a change in asphericity to accommodate more add, but this ultimately changes the fit of the lens. By compensating on the front surface, we avoid that problem," explains Jean Blanchard, president of Blanchard Contact Lens.

However, "There is no single lens that will take care of all presbyopic patients," says Mr. Dickerson. That's why there are many lens options for you to choose from for this group.

Irregular corneas

Keratoconic corneas are among the most difficult to fit. "These patients present a unique fitting situation because no two cones are alike," says Mr. Dickerson. But dissemination of topography has increased the chances of a successful keratoconus fit. "More and more cones are detected early with increased use of topography," says Mr. Blanchard. And early fitting is key. "If a cone patient is fit with-in the early stage with a keratoconic-specific design, the risk of abrasion or progression is greatly reduced, by optimizing lens position, tear exchange, comfort and long-term corneal health."

In many cases, you can send a patient's topography directly to the lab that will base the lens design on the patient's data. "Any time we can get topography for a keratoconus patient, it makes it easier," says Mr. Johnson.

The high-minus lenses these patients generally require create additional spherical aberration. However, lenses that modify the curve and incorporate asphericity on to the back surface of the lens can "counteract the natural spherical aberration in high-minus lenses," says Mr. Blanchard. To address the appearance of halos, some new lenses feature a larger optical zone.

Some keratoconus lens designs allow you to make peripheral changes in different quadrants of the lens without changing the base curve, diameter or optic zone. Jan Svochak, vice president of Tru Form Optics, says, "More symmetrical pooling around the outside of the lens maintains a light touch on the tip of the cone." Other lenses incorporate additional curves into the lens to match the keratoconus mid-peripheral slope.

Another option for tough-to-fit presbyopes is scleral or semi-scleral lenses. "For patients who have undergone penetrating keratoplasty, or those with other highly-irregular corneas, a scleral or semi-scleral lens that fits out past the limbal margin can provide a smooth wavefront, but also doesn't depend on the cornea for centration," says Mr. Dickerson. "Plus since it's so large, it's generally very comfortable with a well-fitting lens."

Ortho-K

The lens on the top was treated with a plasma coat, the one on the bottom was not.

Orthokeratology (Ortho-K), also known as corneal reshaping or corneal refractive therapy (CRT), is another area where GP lenses have an advantage. "We feel this is a great opportunity for the marketplace because it's strictly done with GP lenses," says Mr. Blanchard. But this modality hasn't met expectations. "We hoped ortho-k would spark a bigger interest and practitioners would jump on the band wagon, but that just hasn't happened," says Mr. Johnson. But the lag time may be related to the training requirements and patient selection guidelines.

Dan Bell, president of Corneal Design and of the CLMA, suggests consulting the organization for help. "Optometric practitioners benefit from our many decades experienced contact lens technician consultants," he says.

Dispensing aids

GP labs have also introduced new tools to help you work with the latest designs and find the best fit for your patients. ABBA Optical's multiple visual performance (MVP) dispensing system allows practitioners to dispense custom multifocal lenses immediately. This allows you to offer patients a free in-office trial of a GP lens with out the inconvenience of follow-up visits or additional fees. Base your initial lens selection on the flattest K and spherical refractive error. Power refinement is similar to soft multifocals. ABBA will also provide customized patient brochures free of charge to those who own the system.

Art Optical's Art Keratoconic System (AKS) loaner cone series is intended to help you control the lens' optical diameter according to the base curve relationship. Two sets are available: base curves for the standard set range from 6mm to 7.2mm in 0.10mm steps; the extended set ranges from 5mm to 6.2mm. All lenses have a diameter of 8.5mm, while the optical zone diameter reduces as the base curve steepens. By controlling the optical zone to relatively match the base curve, you can avoid seal off or 360Þ bearing. The powers in the loaner set are also controlled to increase in minus power as the base curve steepens.

Lens treatments

The latest advancement in GP coatings is the plasma coat. Paragon Vision Sciences' Aqua Comfort cold gas plasma coating treatment provides improved wettability. ABBA Optical utilizes the process under the name Hydrolize and Bausch & Lomb is awaiting approval on a similar treatment. "The plasma process that is applied to the surface of many GP lenses today so dramatically increases the initial comfort that it will increase the GP market share," says Mr. Dickerson. "GP lenses can create wettability and deposit issues," says Mr. Johnson. A study conducted by Paragon shows the treatment enhances patient comfort for: dry eyes, oily or filmy contact lenses, and high-Dk lenses that are less wettable. Because plasma treatment makes GPs more comfortable, it may also reduce new wearer adaptation time.