RGPs and Progression Of Myopia: What's New? 

Question: Where does the Singapore study and other research on using RGP lenses to slow the progression of myopia in children stand? 

Answer: The 3-year study is complete, and analysis of the data is now under way. Look for results in the fourth quarter of this year, says Brian Levy, O.D., Ph.D., of Bausch & Lomb, which sponsored the study.

In this study, researchers randomized 300 Singaporean children, ages 7-11 with 2.00D-4.00D of myopia, into two groups; one wore spectacles, the other RGPs. When comparing myopia progression between the groups, researchers will consider axial length of the eye, refractive error, corneal curvature changes and visual habits.

The Singapore study will be the latest chapter in the ongoing debate about whether RGPs can slow the progression of myopia in children. For example, in 1985 J. Perrigin and colleagues fit 100 myopes ages 8-13 in silicone acrylate contact lenses.1 Three years later, the mean increase of myopia was 0.48D vs. 1.53D for children of similar age and initial refractive error who wore spectacles.

C.Y. Khoo and colleagues published results of a pilot study, also in Singapore, in April.2 They looked at some 100 myopic children over 3 years and found that the mean increase in myopia was 0.42D in those children wearing RGPs vs. 0.78D in those children who wore spectacles. In other words, there was a 0.36D “suppression” of the myopia progression in the RGP group. They believe that a smaller increase in axial eye length in the RGP wearers accounted for nearly two-thirds of this suppression, with changes in corneal curvature contributing to the remainder. However, the researchers themselves say further study is necessary. 

Another study, the Contact Lens and Myopia Progression (CLAMP) project is under way at Ohio State University College of Optometry. This 3-year study will involve some 115 children, ages 8-11. Researchers will perform autorefraction and corneal topography, and measure axial length to determine if RGPs can slow the progression of myopia, and if so, how, says principal investigator Jeffrey Walline, O.D.

CLAMP researchers hope to address what they consider a flaw of previous studies: a high dropout rate. Some 44% and 47% of children discontinued lens wear in Drs. Perrigin’s and Khoo’s studies, respectively. All CLAMP study subjects will initially wear RGPs to make sure they can tolerate them. Researchers will then randomize them into groups wearing RGPs or soft contact lenses. 

Question: What are the clinical implications of the Singapore and similar studies?

Answer: The results may help create a new, younger group of contact lens patients, who otherwise might not begin contact lens wear until teen years or later, Dr. Walline says.

In Dr. Khoo’s study, lack of motivation, not contact lens intolerance or ocular complications, was the primary reason cited by those who discontinued RGP wear. “The fact that major complications didn’t occur bodes very well for the fact that RGPs should be a viable option for a lot of youngsters,” says optometrist Janice M. Jurkus of Illinois College of Optometry. 

The results of these studies also may determine whether we present RGPs to parents of myopic children as one option for correcting myopia or as a way to make the child less myopic, says CLAMP study adviser Karla Zadnik, O.D., Ph.D. 

1. Perrigin J, Perrigin D, Quintero S, Grosvenor T. Silicone-acrylate contact lenses for myopia control: 3-year results. Optom Vis Sci 1990;67(10):764-9.
2. Khoo CY, Chong J, Rajan U. A 3-year study on the effect of RGP contact lenses on myopic children. Singapore Med J 1999;40(4):230-7.

Send it to 
Dr. Joseph P. Shovlin 
c/o Review of Optometry
11 Campus Blvd., Suite 100
Newtown Square, PA 19073
Attn.: CLQA
Or fax it to 610-492-1039, or e-mail it to reviewofoptometry@jobson.com.

top