CLAO international researchers share ortho-K, keratoconus study data

Issue: March 2005

ByBarbara Anan Kogan, OD

SAN DIEGO — Here at the third annual Contact Lens and Eyecare Symposium, Japanese ophthalmologists presented scientific papers and posters on their contact lens research, while German and Italian studies were highlighted as “the best” of the 2004 European Contact Lens Society of Ophthalmologists meeting.

Japanese keratoconus designs

“Discomfort, pain, corneal edema, fit instability, contact lens intolerance and poor central and peripheral vision are common problems from keratoconus and post-penetrating keratoplasty,” said Ryoji Yani, MD, PhD. Dr. Yani, of Yamaguchi, Japan, presented a paper by Teruo Nshida, MD, during the Japan Contact Lens Society Symposium, discussing the concept of a dual-base-curve contact lens design for these cases.

“Traditional spherical two- or three-point-touch large, flat or small diameter lenses provide apical clearance even for piggyback designs,” Dr. Yani continued. “The single base curve for irregular astigmatism results in several clinical problems: abrasion and consequent epithelial disorders, such as erosion or superficial punctate keratopathy.”

A specialty gas-permeable dual aspheric base curve design better fits irregular astigmatism caused by keratoconus or corneal surgery, said Dr. Yani. The Aphex KC addresses problems at the apex of the cone, including those caused by corneal abrasions, epithelial disorders, discomfort and pain in the periphery of the cone, along with reduced tear exchange and corneal edema.

Single-base-curve GP: This patient’s conventional GP lens is off center and unstable. Because of the discomfort associated with this lens, she could not open her lids fully.

Aphex KC lens: This lens is positioned essentially at the center of the cornea. Lens movement was good, and the apical clearance seemed sufficient, as revealed by the fluorescein pattern. The dual base curves of the Aphex KC lens allow ideal lens fitting at both the cone and periphery of the keratoconic cornea.

Dr. Yani said that this smaller radius of curvature allows apical clearance and minimizes the chance of development of epithelial disorders. The lens’ larger radius of curvature peripherally, designed to improve both lens centering and tear fluid exchange, has two different curvatures and bevels connected by a reversed radius to obtain a smooth transition between the apical and peripheral curves.

Dr. Yani presented three cases. In the first, a 28-year-old with mild-stage keratoconus required a better-aligned right GP contact lens, which was achieved with an Aphex design.

In the second case, a 26-year-old with contact lens intolerance wore a spherical GP that produced off-center, excessive fluorescein pooling. This patient was fit with a dual-base-curve Aphex design, which exhibited good lens movement and comfort.

In the third case, a 30-year-old’s post-penetrating keratoplasty shape created irregular astigmatism with a flatter center and steeper periphery. The PCS-1 (Post Corneal Surgery type 1) dual-base-curve design provided good central and peripheral vision, comfortable wear, clearance for tear exchange and a stable fit.

Japanese ortho-K lenses

Tokyo’s Iwane Mitsui, MD, improved corneal surface irregularities induced by radial keratotomy and LASIK surgeries, eliminated remaining or reappearing refractive errors and resolved keratoectasias with advanced ortho-K GP contact lens designs. According to Dr. Mitsui’s CLES poster, he addressed instability of flap formation, diffuse lamellar keratitis, epithelial ingrowth and myopia regression post-refractive surgery.

Dr. Mitsui followed patients’ intraocular measurements, corneal endothelial count, corneal curvature and shape and visual acuity with correction and without for 2 years, as additional surgeries were not indicated. He found that 95% of the patients improved their uncorrected visual acuity from <20/30 to 20/20 or better, 86% improved to 20/15 or better and 76% improved to 20/10. The mean spherical equivalent from -2.42 D of myopia improved to -0.73 D ± 0.64 D. No ocular abnormalities occurred from flap formations or increased intraocular pressure.

Dr. Mitsui’s Ocular Surface and External Integrated Remodeling Therapy (OSEIRT/Ortho-K) GP design consists of four to five curves with a large optic zone and steep reverse curves. “It uses the highest Dk materials to supply sufficient oxygen for the complicated corneal surface and ectasia after refractive surgeries,” Dr. Matsui told Primary Care Optometry News. “The OSEIRT design, which now can cover >10 D of myopia and >3 D of severe astigmatism, will soon be available for hyperopia,” he added.

European keratoconus, ortho-K designs

Albert Franceschetti, MD, president of the European Contact Lens Society of Ophthalmologists, presented a CLAO International Symposium reviewing research from the “best” of its 34th European Congress held in October in Budapest, Hungary.

Alberto Manganotti, MD, of Verona, Italy, designed a custom GP contact lens for 27 keratoconus patients and 45 eyes to avoid apical touch using Firenze Company’s Eikon Calcon System with data from topography. The program provides simulation of the fluorescein image of the lens and instruction on how to modify the parameters until the apex of the cornea appears free, then allows the fitter to design a custom-made lens after sending data via the Internet.

“The results were very encouraging for these GP contact lens wearers, with much better visual acuity, as the design was closer to the corneal profile, much better tolerated and offered improved comfort for 68% of the patients,” Dr. Franceschetti said of this Italian keratoconus research.

German optometrist Andreas Berke von Köln presented a 2-year follow-up of 71 patients who completed ortho-K treatment. The mean age was 26.7 ± 6.3 years, mean refraction was 2.60 D ± 1.25 D, corneal thickness was reduced by 14 micrometers, and the horizontal radius increased by about 0.6 mm and 0.50 mm vertically. Visual acuities for patients with an average 2.60 D of myopia achieved 20/20 or better.

Dr. Franceschetti summarized, “All patients experienced a contrast sensitivity reduction and were asymptomatic after 2 years, while halos were bothersome when the pupil dilated in reduced illumination.”

Hamburg, Germany, optometrist Sylvia Ostrowski fit 11 patients between 28 and 35 years of age with ortho-K contact lenses while she was in a Berlin optometry school. In her short-term study, Dr. Ostrowski found that patients achieved a visual acuity of 20/20 by the third day.

At the conclusion of the 5-week study, patients experienced reduced mesopic visual acuity, reduced central corneal thickness (by an average of 10.5 micrometers), an average peripheral swelling of 3.37 micrometers and a six-times increase in the average spherical aberration from the Zernicke polynomial.

For Your Information:

Ryoji Yanai, MD, PhD, can be reached at the Department of Biomolecular Recognition and Ophthalmology, Yamaguchi University School of Medicine, 1-1-1 Minami-Koguski, Ube-City, Yamaguchi, Japan; +81-836-22-2278; fax: +81-836-22-2334; e-mail: r-yanai@yd5.so-net.ne.jp.

Iwane Mitsui, MD, can be reached at Mitsui Medical Clinic, 5-4-11 Yamaguchi Daini Building 3F A Kasaka, Minato-Ko, Tokyo 1070052, Japan, +81-3-55-70-2321; fax: +81-3-5570-2327; e-mail: iid@ortho-k.co or mitsui@ortho-k.jp.

Albert Franceschetti, MD, can be reached at 1 JP Maillard, CH-1217 Meyrin (Geneva), Switzerland; +41-22783-1090; fax: +41-22783-1099; e-mail: albert@franceschetti.net.

Barbara Anan Kogan, OD, can be reached at 4501 Connecticut Ave. NW, Suite 102, Washington DC 20008-3711; phone and fax: (202) 244-1324; e-mail: bakogan@mindspring.com.