Clinical Research in Myopia Control

This retrospective study of children younger than age 18 years old provides evidence that ortho-k can reduce the rate of progression of childhood myopia over the long term compared to single vision spectacle lenses. This is one of the major studies that proves that ortho-k can last at least 10 years.

On average, patients between ages 6-10 years old subjects wearing ortho-k molds have a slower increase in axial elongation (eyeball length) by 43% compared to subjects wearing spectacle single vision glasses. Younger Children had faster axial elongation and may benefit from early orthokeratology intervention.

The CLAMP study began as a way to study the efficacy of using rigid contact lenses to treat myopia in young children as well as determine the mechanism of the treatment if treatment is useful. The study was also used to compare issues of vision and comfort between rigid and soft contact lens wearers. At the end of the study it was found that rigid gas permeable lenses slow the progression of myopia in small children more than soft lenses. However, the decreased refractive error does not also mean that the axial growth is slowed. The study also indicated that the change in corneal curvature is reversible, and is most effective in the first year of use.

This study showed that orthokeratology contact lenses reduced the progression of nearsightedness in kids between 9 and 15.  The authors of the CANDY study found that the amount myopia in children that wore spectacle single vision lenses increased at a rate of .46D per year while those children wearing the lenses progressed at only .03 diopters per year.

The CRAYON Study was conducted to compare the growth of the eye between myopic children wearing corneal reshaping (CR) contact lenses and alignment fitted gas permeable (GP) and soft (SCL) contact lenses.  Over two years, the GP group grew, on average, 0.37 mm more than the CR group (p=0.0001) and the SCL group grew, on average, 0.37 mm more than the CR group (p=0.0001).

This study compare 1,765 six year olds and 2,367 twelve year olds and compares how lifestyle can affect refractive error. This study found that high levels of near work and low levels of outdoor activity had more nearsightedness. On the other hand, children who spent more time outdoors were associated with less myopia.

This is another study that was designed to investigate whether or not orthokeratology can effectively reduce and control myopia in young children, by comparing lens use to eyeglasses use. The study monitored growth of axial length, vitreous chamber depth, corneal curvature, and relationships with changes of refractive errors. The study indicated that those who used orthokeratology at night, found that their vision was improved and acceptable throughout the day. The study also showed that those with a higher myopia prescription show a better decline in progression than those without.

This study investigated controlling myopia progression with rigid gas permeable contact lenses versus eyeglasses. Studies showed that those who wore eyeglasses has an increase in myopia of .78 D per year, whereas using gas permeable lenses slowed progression to .42 D per year. The study also showed more axial growth in those that wore eyeglasses than those that wore GP lenses. Thus the decrease in progression of myopia is stronger in GP lenses because of axial length growth reduction and corneal flattening.