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Today’s GP lenses provide clarity, comfort from young myopes to presbyopes
ORLANDO, Fla. — “GP (oxygen permeable) contact lenses, as a health care device and not a commodity, are the lens of choice to increase and improve visual acuity in patients with keratoconus by an average of three to four lines on the Snellen chart,” said Ed Bennett, OD, MSEd. Dr. Bennett, executive director of the RGP Lens Institute, addressed Contact Lens Society of America (CLSA) members here at the first Contact Lens Eyecare Symposium.
“Of more than 3,300 contact lens practitioners responding to a Contact Lens Manufacturers Association survey, 69% believe GPs slow myopia progression,” said Dr. Bennett.
“Today’s ultra-thin GP lens designs have benefits over conventional thickness designs and are great problem-solvers,” Dr. Bennett told Primary Care Optometry News. By reducing the lens mass as much as 30% to 50%, Dr. Bennett pointed out, “You can increase the likelihood of an optimum lens-to-cornea fitting relationship, as well as increase initial comfort with this improved fitting relationship and thinner edge profile. Distance and near visual acuity benefits can be easily achieved for conditions such as blurred vision, corneal desiccation, decentration and lens design deficiencies.”
Dry eye, astigmatism
Many patients wear spectacles because they believe their astigmatism or dry eye would make contact lens wear difficult. However, “45% of those who try to get contact lenses have at least 0.75 D of astigmatism,” said Australian contact lens researcher, John Mountford, OD, DipAppSc. “This creates a tremendous opportunity to fit GP contact lenses.”
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In a lecture on GP fitting, incoming Contact Lens Association of Ophthalmologists (CLAO) president, Peter Kastl, MD, PhD, said red flags to identify candidates are raised when patients exhibit 3 D of corneal astigmatism and more than 0.50 D of residual cylinder.
In another CLAO symposium, former CLAO president Gary N. Foulks, MD, said, “Dry eye and meibomian gland dysfunction represent one of the primary reasons for discontinuing contact lenses. Once you have selected a GP contact lens material as the most compatible for that patient, he or she needs special instructions on how to enhance tear film stability. Eyelid warming, lid massage, doxycycline as a pharmaceutical and omega 3 fatty acid as a nutraceutical will prevent dropouts.”
Dr. Kastl pointed out that GP lenses provide a crisper image, and “As they have no water content, they are safer than soft materials, which contain water. Soft contact lenses can act as ‘culture media’ for microbials, whereas GPs do not.”
Phyllis Rakow, FCLSA, reported: “The deposit-resistant surfaces of GPs, their ease of cleaning and their high oxygen permeability are important for the maintenance of a healthy eye. I always make sure every GP wearer, new or experienced, is shown how to blink properly in order to lubricate the eye with tear film mucin and prevent peripheral desiccation. I also make sure each patient is given a handout explaining these things.”
To further enhance a GP contact lens wearer’s ocular health, Ms. Rakow warns patients about the importance of rinsing their lens cases and refilling them with fresh disinfecting solution nightly. “This,” she said, “will avoid loss of solution efficacy and ensure that all microorganisms will be killed effectively.”
Life-long contact lens wear
Among the future directions of GP contact lenses, Dr. Bennett foresees improving the quality of life for young people. “Corneal reshaping and myopia control are exploding with new advancements in technology and lens design, accompanied by overnight wear and an extremely rapid reduction in myopia,” he said. “If the results of the soon-to-be completed 3-year Contact Lens and Myopia Progression (CLAMP) study are consistent with previous myopia studies, this should provide definitive evidence that GPs control myopia. The Houston myopia study, with 8- to 13-year-old myopes, resulted in a 0.48-D total increase in myopia over 3 years for the GP-wearing group and about 1.5-D (i.e., a threefold increase) increase in myopia for the spectacle-wearing group over the same period of time.
“In the future, I see an increasing popularity in orthokeratology and Corneal Refractive Therapy for young myopic patients,” continued Dr. Bennett. “I also see practitioners taking advantage of the growing number of lenses with improved comfort and visual clarity both at near and far to meet the growing demand with fitting presbyopic patients with GP bifocal contact lenses.”
Also looking into the future was Brien A. Holden, PhD, FAAO, professor at the University of New South Wales and CEO of the Cooperative Center for Eye Research. “Myopia is endemic in Asia for 93% of Taiwanese girls and 78% of Taiwanese boys and up to half of the 1.2 billion Chinese,” he said. “The number of individuals with presbyopia is increasing, which provides an opportunity for life-long contact lens wear.”
Dr. Mountford added: “The ability to improve high contrast visual acuity an average of six lines with corneal reshaping is a new technology. We are, and will be, studying the corneal physiology and cellular response of the epithelium and keratocytes for the long-term effects of this reshaping.”
Treating keratoconus
One in every 2,000 people in Australia have keratoconus. Dr. Mountford predicted, “There will be numerous keratoconus designs and materials in addition to those available today to meet the future needs of the early, mid and advanced stages while ensuring good tear exchange.”
Incoming CLSA president Marcus Soper, FCLSA, advocated better monitoring corneal changes to make the appropriate GP design as the disease advances. “More and better information about the irregularities of the apex of the keratoconic cornea will lead to a better designed GP contact lens, especially with topography.”
Mark Andre, FCLSA, of the Casey Eye Institute, Portland, Ore., told Primary Care Optometry News that scleral rigid lenses are an emerging trend in GP lenses. This type of lens has been used to restore visual acuity for patients who progressed to low vision due to keratoconus and corneal trauma.
Designing other custom GPs is “becoming easier when the practitioner compares the horizontal visible iris diameter (HVID) and measures effective corneal curves in consideration with the patient’s genetic background,” Mr. Andre continued. “Typically, the corneal diameter of an Asian eye is smaller, where a European and Scandinavian HVID may be larger. This will enable better matching the shape of the contact lens to the shape of the eye.”
For Your Information:
- Ed Bennett, OD, MSEd, can be reached at the University of Missouri-St. Louis School of Optometry, 8001 Natural Bridge Rd., St. Louis, MO 63121; (314) 516-6258; fax: (314) 516-6708; e-mail: ebennett@umsl.edu.
- John Mountford, OD, DipAppSc, can be reached at 141 Queen St., Suite 7, 12th Floor, Brisbane, QLD 4000, Australia; (61) 7-3221-2643; fax: (61) 7-3221-1946; e-mail: besty@bigpond.net.au.
- Peter Kastl, MD, PhD, can be reached at Tulane University Hospital and Clinic, Department of Ophthalmology, 1415 Tulane Ave. HC 38, New Orleans, LA 70112; (504) 588-5804; fax: (504) 584-2684; e-mail: pkastl@tulane.edu.
- Gary N. Foulks, MD, can be reached at the Cornea and External Disease Service, University of Pittsburgh Medical Center’s Eye and Ear Institute, 203 Lothrop St., Pittsburgh, PA 15213-2582; (412) 647-2205; fax: (412) 647-5119; e-mail: foulksgn@msx.upmc.edu.
- Phyllis Rakow, FCLSA, can be reached at 73 Yorktown Rd., East Brunswick, NJ 08816; (732) 254-6413; fax: (609) 655-3685; e-mail: rakow73@comcast.net.
- Brien A. Holden, PhD, FAAO, can be reached at CRCERT, Level 4, North Wing, Rupert Myers Bldg., Gate 14, Barker St., University of New South Wales, Sydney, Australia 2052; (61) 29385-7418; fax: (61) 29385-7401; e-mail: F.zenatti@crcert.unsw.edu.au.
- Marcus Soper, FCLSA, can be reached at Soper Brothers, 1213 Hermann Dr., Suite 320, Houston, TX 77004; (713) 521-1263; fax: (713) 521-1264; e-mail: Soper@flash.net.
- Mark Andre, FCLSA, can be reached at Casey Eye Institute, 3375 SW Terwilliger Blvd., Portland, OR 97201; (503) 494-5536; fax: (503) 494-5372; e-mail: mandrecei@aol.com.
- Barbara Anan Kogan, OD, can be reached at 4501 Connecticut Ave., NW, Suite 102, Washington, DC 20008-3711; (202) 244-1324; e-mail: bakogan@mindspring.com. Dr. Kogan receives funding from the Contact Lens Manufacturers Association.