Specialty contacts: improved designs, materials allow quicker fitting, greater success

Once considered complex and time-consuming, the process of fitting patients with specialty contact lenses has been significantly improved by advances in lens technology and design.

“We are now able to fit patients quickly and with tremendous patient satisfaction,” said Arthur Epstein, OD, FAAO, director of contact lens service at North Shore University Hospital, NYU School of Medicine. “In the past, we have looked at specialty lens fitting as complex and tedious, and so we’ve charged more and made a big deal of it. Patients just want to be fitted quickly and successfully.”

With a variety of quality products available for different visual needs, practitioners are able to fit patients with the specialty lens that is most compatible to their visual, comfort and lifestyle needs.

Ocular Sciences Biomedics Toric

A relatively common phenomenon, astigmatism once meant an inability to wear soft contact lenses. Currently, astigmatism can be managed with toric hydrogels. One such lens is Ocular Sciences’ Biomedics Toric, with which Dr. Epstein has had a good deal of experience.

“We see a significant percentage of fairly complex patients, so, for us, a toric lens is actually sort of a blessing,” he said. “And we were impressed by the fact that, at a time when toric lenses have advanced dramatically and we have a lot of options, this lens is a standout.”

The Biomedics Toric features a base curve of 8.7 mm, a sphere power range to –6.00 D (in 0.25-D increments) and cylinder power options of 0.75 D, –1.25 D and –1.75 D.

The lens’ ease of fit is one of its biggest advantages, Dr. Epstein said. “This is one of those lenses that you can really fit from the refraction, just with compensation for vertex distance,” he said.

Dr. Epstein said he and his colleagues did a study on the lens at one point, yielding impressive results. “Just fitting empirically from spectacle refraction, we were within a small fraction of a diopter, in about 99% of the patients — that is in sphere, cylinder and with an axis that was usually right on target,” he said.

Dr. Epstein said although practitioners generally think of toric lenses for patients with at least 1.00 D of cylinder, he has found that the Biomedics Toric can be used with patients who have even less cylinder.

“It is so simple to fit, so reproducible, so direct a path to a good result, that you can even fit patients with very small amounts of cylinder reliably,” he said. “So, with a quantifiable difference, they’ll see better. This is basically a lens for a significant number of patients.”

Dr. Epstein said, in the past, there have been flaws associated with toric lenses, including significant vascularization and staining inferiorly, due to mechanical problems with the prism ballast. Lack of oxygen due to relative thickness is also a problem linked with toric lenses, he said.

“But the Biomedics Toric is revolutionary in a lot of different ways,” he said. “It was designed specifically to distribute the prism ballast in a very predictable, very even manner. So you end up with a fairly even distribution of lens material.”

Proclear Compatibles Toric

Made from the dehydration-resistant material omafilcon, the Proclear Compatibles Toric lens (CooperVision) retains approximately 96% of its original water content for as long as 12 hours, said Nikki Iravani, OD, director of clinical research and professional relations for CooperVision.

“The main advantage of the material is that it remains comfortable all day long,” Dr. Iravani said. “Omafilcon has Food and Drug Administration clearance for the claim that it may provide improved comfort for contact lens wearers who experience mild discomfort or symptoms related to dryness during lens wear.”

In particular, omafilcon is helpful to those patients with “end-of-the-day” dryness, Dr. Iravani said. “This material is ideal for patients who work in front of computers all day and their blink rate is reduced,” she said.

Dr. Iravani said the Proclear Compatibles Toric has an optimized back-surface toric design, with a thin profile and high oxygen permeability. The mid-periphery prism design of the lens combines high levels of stability with the comfort of the thin, lower-edged profile, Dr. Iravani said.

The lens has a base curve of 8.8 mm, sphere powers of +4.00 D to –6.00 D in 0.25-D steps, and three cylinders in 10-degree axes around the clock. “The axis is 0° to 180° in 10° steps,” Dr. Iravani said. “It’s laser-marked at 6 o’clock and 15° to either side.”

Dr. Iravani said fitting this lens is a fairly straightforward process. “You select your power based on the spectacle prescription and convert it to the minus-cylinder form, like you would with any other lens,” she said. “You select the cylinder power that is closest to the patient’s cylinder and the axis that is closest to the spectacle prescription.”

Dr. Iravani said there isn’t necessarily an “ideal” candidate for the Proclear Compatibles Toric, but there are patients who stand to benefit most from the lens.

“Patients who don’t have any particular dry eye issues may be comfortable in any toric lens,” she said. “This contact lens is not only good for the average patient, it is suitable for patients who have end-of–the day discomfort issues and dry eye.”

Frequency 55 multifocal

Launched in 2001, the Frequency 55 multifocal from CooperVision is a two-lens system recommended for monthly replacement, with a distance lens design for the dominant eye and a near lens design for the non-dominant eye. This combines spherical and aspheric optics.

Joel Halpern, OD, FAAO, director of Halpern Eye Associates in Dover, Del., has had extensive experience fitting the Frequency 55 multifocal. Dr. Halpern said that although he has had some degree of success with other bifocal contact lenses in the past, the Frequency 55 is the most impressive to date.

“I think for ease of fit and clarity for patients, the Frequency 55 multifocal from CooperVision is the best bifocal I have ever seen,” he said. “It is easy to fit, and, optically, it is a great lens. People are very happy with it.”

The Frequency 55 lens features a D lens for the dominant eye, with a spherical zone of 2.3 mm, an aspheric annular zone of 5.0 mm and a spherical annular zone of 8.5 mm.

Made of methafilcon A, the lens is available in sphere powers of +4.00 to –6.00 D (in 0.25-D steps). Its add powers are +1.50, +2.00 and +2.50 D.

The lens also features a thin mid-apex edge profile and a 324 trial lens rack that contains every parameter for trial fitting.

“There is a D lens and an N lens; I have been more inclined to start using both of these for both eyes,” Dr. Halpern said. “When the patient comes in and says he or she has a problem reading, then I will try the N lens. I am probably having an 85% success rate, if not higher, and most of my patients leave with two D lenses on.”

Dr. Halpern said the best candidate for the Frequency 55 is the patient with less than 0.75 D of astigmatism correction, both farsighted and nearsighted.

“If a patient has a lot of astigmatism, the other lens I go to is UltraVue’s bifocal soft astigmatic lens,” he said. “It is a little bit more difficult to fit, but it is a good lens for astigmats.”

He said he sees no disadvantages to the lens, but added that the success of the lens is based on the patient’s needs and lifestyle.

“It goes by lifestyle – people who want to live in a lens continuously and never have to take it out are not good candidates,” he said. “As with any other soft lens, patients who spend time around fumes and odors are not good candidates. But I see no contraindications with this lens.”

Presbylite RGP bifocal

The bifocal design of the Presbylite RGP bifocal (Procornea) has a triangle-shaped near segment that is cut spherically for near needs, a spherical zone that encompasses 70% of the front optics for distance needs and a small aspherical area at the top of the triangle for intermediate tasks.

According to Robert Ryan, OD, a private practitioner in Rochester, N.Y., the lens features a streamlined design, consistently stable orientation and improved contrast sensitivity as compared to aspheric multifocals. “The Presbylite design has been an important part of our practice for the past few years,” Dr. Ryan said.

Dr. Ryan said the lens is essentially fit as a spherical multi-curve lens, which generally facilitates an easy transition for emerging presbyopes.

He said that, often, the fitting relationship must be slightly steeper (0.10–0.20 mm) than typical to discourage superiorly positioned lenses. Dr. Ryan explained that high-riding lenses interfere with clear distance acuity by placing the intermediate zone before the line of sight.

“It is critical that these lenses drop quickly and fully after each blink, which is the rule in translating designs such as this,” he said.

Therefore, Dr. Ryan said, careful pre-fitting assessment should rule out the following: high levels (>1.50 D) of against-the-rule corneal toricity, superiorly displaced or significant lateral decentration of the corneal apex upon topographical analysis, narrow palpebral fissures, particularly when associated with reverse ptosis, increased flaccidity of the eyelids, poor or incomplete blinking and keratoconjunctivitis sicca or other lid or ocular surface disease.

“Due to its unique design with a generous triangular point area, up to 30° of nasal rotation is often acceptable without generating patient symptoms,” Dr. Ryan said. “Certainly, if excessive rotation is encountered, this can be compensated for by rotating the base of the stabilizing prism.”

Ortho-K, Paragon CRT

In June 2002, the FDA approved Paragon Vision Sciences’ Paragon CRT lens for overnight corneal refractive therapy (CRT) for the temporary reduction of myopia. Another method of reshaping the cornea, orthokeratology (ortho-K), is FDA approved for daytime use and has been practiced by some doctors for decades.

New lens designs and manufacturing techniques have enabled both ortho-K and CRT to achieve a greater degree of success.

“In the past, any type of corneal reshaping, particularly orthokeratology, has been looked at as almost cultish,” said John L. Schachet, OD, former president of the Colorado Optometric Association who practices in Englewood, Colo. “Now, we finally have some scientific evidence that it does work. Practitioners can now have a more open-minded view of this and be successful.”

Joe Barr, OD, a professor at the Ohio State University College of Optometry, has had some experience working with CRT. He discussed the functional limits of this technology.

“The FDA approval is for up to –6 D, and, certainly, it gets more difficult the closer you get to –6,” he said. “Experienced practitioners feel they can do –5. The fact of the matter is, no matter what the power is, most of the time it works well, and sometimes it doesn’t.”

Dr. Schachet said the success rate for these procedures depends upon certain other factors. “Number one, the patient needs to be willing to be compliant and go through the process, which means wearing the lenses every night,” he said. “That’s a critical factor. It’s the single biggest factor you have.”

Screening is also a key factor in promoting the success of these treatments, Dr. Schachet said. “I’m talking about determining what sort of corneal shape we have in terms of corneal topography,” he said. “Does it look like a cornea that a lens will center well on?”

Given these factors, Dr. Schachet said clinicians can generally expect a 70% to 80% success rate for CRT.

“In the study we did, there was over a 90% success rate if you considered 20/40 or better as the final outcome,” he said. “Based on binocular acuity, 67.4% of patients saw 20/20 or better and 93.3% saw better than 20/32. And that was done so that the outcome’s analysis would be compared to laser vision correction.”

Dr. Barr said he has not noticed a significant decline in end-of the-day visual acuity for those using CRT. “Our data show that people who are successful only lose about a line of acuity,” he said. “So if they wake up with 20/20, 20/25 or 20/30, then at the end of the day, they are going to be 20/25, 20/30 or 20/40.”

In this context, the “end of the day” means 5 p.m., Dr. Barr said.

“I know of no good data that addresses 8 p.m.,” he said. “The patients who are successful don’t complain about that.”

Dr. Barr said the FDA approval of CRT is bringing about a change in the way contact lens corneal reshaping is perceived.

“I think what is happening here is interesting,” he said. “In the past, orthokeratology was practiced by very few people. With FDA approval, contact lens corneal reshaping or corneal refractive therapy is becoming more of a mainstream procedure.”

For Your Information:

• Arthur Epstein, OD, FAAO practices at North Shore Contact Lens and Vision Consultants. He can be reached at 1025 Northern Blvd., Suite 94, Roslyn, NY 11576; (516) 627-4090; fax: (516) 627-4169.
• Nikki Iravani, OD, is director of clinical research and professional relations at Cooper Vision, Inc. She can be reached at 200 WillowBrook Office Park, Fairport, NY 14450; (800) 341-2020 ext. 3354; fax: (888) 385-3217.
• Joel Halpern, OD, FAAO is the director of Halpern Eye Associates in Dover, Del. He can be reached at 885 S. Governor’s Avenue, Dover, DE 19904; (302) 734-5861; fax: (302) 734-1921.
• Robert A. Ryan, OD, FAAO is a private practitioner in Rochester, NY. He can be reached at 169 Rue de Ville, Rochester, NY 14618; (585) 271-2990; fax: (585) 271-6321.
• John Schachet, OD, FAAO practices in Englewood, Colorado. He can be reached at 8586 Arapahoe Road #100, Englewood, CO 80112-1417; (303) 771-4221; fax: (303) 721-7759.
• Joseph T. Barr, OD, MS, FAAO, teaches at OSU College of Optometry. He can be reached at 320 W. 10^th Avenue, Columbus, OH 43218; (614) 292-0437; (614) 688-3285. Neither Dr. Epstein, Dr. Halpern, Dr. Schachet nor Dr. Barr has a direct financial interest in any of the products mentioned in this article, nor are they paid consultants for any of the companies mentioned. Primary Care Optometry News could not determine if Dr. Ryan has a direct financial interest in any of the products mentioned or if he is a paid consultant for any of the companies mentioned in this article.

• The Biomedics Toric is available from Ocular Sciences, 1855 Gateway Blvd., Concord, CA 94520-3200; (800) 972-6724; fax: (610) 615-9702; Web site: www.ocularsciences.com.
• The Proclear Compatibles Toric and the Frequency 55 multifocal are available from CooperVision Inc., 200 WillowBrook Office Park, Fairport, NY 14450; (716) 264-3248; fax: (716) 264-3823; Web site: www.coopervision.com.
• The Presbylite RGP bifocal is available from Procornea; Web site: www.presbylite.com.
• The Paragon CRT lens is available from Paragon, 947 E. Impala Avenue, Mesa, AZ 85215; (480) 507-7674; fax: (480) 926-7369; Web site: www.paragonvision.com.