Two studies examine overnight orthokeratology in adults, children

Issue: December 2002

ByBarbara Anan Kogan, OD

COLUMBUS, Ohio, and BOSTON – Separate studies based in these U.S. cities are examining the safety and efficacy of overnight orthokeratology in both children and adults, with improvements in visual acuity reported.

COOKI study

chart
Eleven-year-old COOKI patient: At the baseline visit, his manifest refraction was -2.25 sphere in the right eye and -2.00 -0.25 × 180 in the left eye. At the 1-week follow-up appointment, the refraction was +0.25 -0.50 × 090 in the right eye and +0.25 sphere in the left eye, both corrected to 20/20. Unaided visual acuities were 20/25 in the right eye and 20/20 in the left eye.

Desired fit: Desired fluorescein pattern and fit of a Paragon Corneal Refractive Therapy contact lens.

The Children’s Overnight Orthokeratology Investigation (COOKI) pilot study for 8- to 11-year-old children was conducted at The Ohio State University (OSU) College of Optometry and at the New England College of Optometry in Boston. According to principal investigator Jeffrey J. Walline, OD, PhD, COOKI sought to determine the safety and efficacy of overnight ortho-K in children.

Eligible COOKI patients were current eyeglass wearers who have a maximum of 5.0 D of myopia with up to 1.5 D of astigmatism. COOKI used the oxygen permeable Paragon Corneal Refractive Therapy (CRT) contact lens (Paragon Vision Sciences, Mesa, Ariz.), which was recently approved by the Food and Drug Administration for overnight corneal reshaping for the temporary reduction of myopia. The children were followed for up to 6 months.

Dr. Walline’s data show an average wearing time of 67.8 hours per week. More than two-thirds of the children reported that the lenses were “usually comfortable” or “always comfortable.” Average uncorrected visual acuity was “better than 20/25 with stable vision after just 2 weeks of contact lens wear, and more than half of the children reported never having handling problems with the lenses,” said Dr. Walline, a research scientist at OSU.

Using a subscale from the National Eye Institute’s (NEI’s) Visual Function Questionnaire, the children rated their vision from 0 (completely blind) to 100 (perfect vision). None of the children in the COOKI pilot study, which was funded by Paragon, had previous contact lens wear.

Corneal staining was observed in 56.1% of the enrollees, and half of the staining was located centrally. “While staining is much more prevalent after overnight wear, the vast majority of it is less than grade 2, and the prevalence reduced from 60% to 20% within 6 hours after contact lens removal. No adverse reactions, such as neovascularization or microcysts, were noted throughout the 6 months of follow-up,” he said.

Dr. Walline told Primary Care Optometry News that the prevalence of myopia increases from 2% of children entering kindergarten in the United States to 15% of children entering high school. Therefore, he stressed the need for early childhood eye exams.

Dr. Walline is also the principal investigator for the NEI-sponsored Contact Lens and Myopia Progression (CLAMP) Study, which is examining the effects of alignment-fitted gas-permeable contact lenses on myopia progression in 8- to 11-year-old children and what causes certain eyes to progress more slowly. This study will be completed in May 2003.

LOOK study

The Lenses for Overnight Ortho-Keratology (LOOK) pilot study, which is being conducted at OSU, The New England College of Optometry and the Southern California College of Optometry in Fullerton, evaluated the success and safety of treatment with overnight ortho-K contact lenses in adults.

Marjorie J. Rah, OD, PhD, from the New England College of Optometry, the COOKI co-investigator and LOOK principal investigator, said, “LOOK began in late 1999 for subjects between 18 and 39 years old who have a maximum of 3.0 D of myopia and 2.0 D of astigmatism. They can be current gas permeable contact lens wearers, but must abstain at least 2 weeks prior to enrollment.

“Our conclusions are that orthokeratology improves unaided visual acuity and reduces myopic refractive error for at least 6 hours following lens removal,” Dr. Rah said. A high proportion of subjects achieved 20/20 high contrast visual acuity and uncorrected low contrast visual acuity of at least 20/40.

“We evaluated both the Paragon CRT and Fargo 6 GP (GP Specialists, Phoenix) contact lenses. The Paragon CRT uses a sigmoid-designed secondary curve and is plano in the third curve – each of which contributes to making the junctions smoother,” she said.

“The Fargo 6 design has radii of curvature. In the 1960s and 1970s, orthokeratology contact lenses were traditional PMMA materials in tricurve designs that had a tendency to decenter, but, with the advent of reverse geometry GPs, the lenses center better,” she explained. Enrollees are evaluated at the morning and afternoon visits at 1 day, 1 week and 1, 3, 6 and 12 months.

“Safety has been the same for both the LOOK and COOKI pilot studies, and we expect success in efficacy at the end of both the COOKI and LOOK pilot studies,” Dr. Rah said. “Due to preliminary results in the COOKI pilot study, we anticipate a higher success rate with this study and subsequent clinical trial.”

Six-month results show that 27 of 60 eligible patients completed a 6-month visit with a mean change in equivalent manifest refraction. Of these 27, 74.1% achieved 20/20 uncorrected visual acuity at the morning visit in both eyes with high contrast visual acuity; corneal staining was present in both eyes in 75% of patients, with between 90% and 95% having less than a grade 2; a corneal imprint was seen in 22.2% of right eyes and 15.4% in left eyes; and microcysts were seen in 29.6% of the right eyes and 25.1% of the left eyes. No corneal infiltrates or permanent cornea damage was reported.

According to Dr. Rah, the pilot study was funded by Paragon Vision Sciences and the Ezell/CIBA Vision Fellowship from the American Optometric Association. It received the FDA’s investigational device exemption (IDE) approval for both contact lenses for overnight wear. Data collection for the LOOK pilot study has been completed and will be analyzed in the near future.

For Your Information:

Jeffrey J. Walline, OD, PhD, can be reached at The Ohio State University College of Optometry, 338 W. 10^th Ave., Columbus, OH 43210-1240; (614) 292-6603; fax: (614) 292-4705; e-mail: walline.1@osu.edu. Dr. Walline received materials for the COOKI study, as well as travel expenses and honoraria from Paragon Vision Sciences.

Marjorie J. Rah, OD, PhD, can be reached at the New England College of Optometry, 1255 Boylston St., Boston, MA 02215; (617) 236-6330; fax: (617) 236-6340; e-mail: rahm@ncopost.neoptometry.edu. Dr. Rah is a paid consultant for Paragon Vision Sciences.