Optimal Atropine Concentration for Two Year Myopia Control Affirmed

By Marilynn Larkin

January 22, 2020

NEW YORK (Reuters Health) - Atropine 0.05% remains the optimal concentration for slowing myopia progression among Chinese children, the LAMP study extension shows.

In a 2011 study, atropine 0.01% - but not 0.1% or 0.5% - resulted in better myopia control in the second year of treatment than in the first year (http://bit.ly/374fGK5), Dr. Jason Yam of the Chinese University of Hong Kong told Reuters Health by email. "This led to the suggestion of similar efficacy of 0.01% atropine with 0.5% and 0.1% atropine over two years."

By contrast, the first-year results of the LAMP (Low-concentration Atropine for Myopia Progression) study showed that 0.05% atropine conferred the best treatment-side effect ratio among 0.05%, 0.025%, and 0.01%.

The current study extended LAMP to two years to assess the efficacy and safety of these low concentrations of atropine over two years.

Three hundred eighty-three (87%) of the 438 children in the one-year LAMP study continued in the second-year extension. Participants had myopia of at least -1.0 diopter (D) and had been randomized to receive atropine 0.05%, 0.025%, 0.01%, or placebo once daily in both eyes.

For the extension trial, children in the placebo group in the first year were switched to 0.05% atropine from the beginning of the second year follow up; those in the 0.05%, 0.025%, and 0.01% groups continued on the same regimen.

The primary outcomes were between-group differences in spherical equivalent (SE) and axial length (AL).

As reported in Ophthalmology, over the two-year period, the mean SE progression was 0.55, 0.85, and 1.12 in the 0.05%, 0.025%, and 0.01% atropine groups, respectively; corresponding mean AL changes were 0.39 mm, 0.50 mm, and 0.59 mm.

The efficacy of 0.05% and 0.025% concentrations remained similar to the first year, but the 0.01% group showed mild improvement.

For the group that switched from placebo to 0.05% atropine, myopia progression was significantly reduced, with an SE change of 0.18D in second year versus 0.82D in first year, and AL elongated 0.15 mm in second year versus 0.43mm in first year.

Accommodation loss and change in pupil size in all concentrations remained similar to the first-year results. Visual acuity and vision related quality of life remained unaffected. All concentrations were well tolerated.

The authors conclude, "Over two years, the observed efficacy of 0.05% atropine observed was double that observed with 0.01% atropine, and it remained the optimal concentration amongst the studied atropine concentrations in slowing myopia progression."

Dr. Yam said, "While our current report confirmed that 0.05% remained the optimal concentration over two years, our third year (extension) will look into its efficacy over three years, and also (assess) whether treatment should be continued or stopped at the third year."

"Other dosing studies are needed in different populations such as Caucasian," he added, "as our study subjects are all Chinese, who have a pigmented iris."

Dr. Lori Ann Kehler, Division Chief, Optometry at the Vanderbilt Eye Institute in Nashville, commented in an email to Reuters Health, "Low-dose atropine for the treatment of myopia progression is an exciting development in pediatric eyecare. The authors (of the current study) again postulate that 0.05% atropine is the most effective dose of atropine and side effects were well-tolerated."

"Several significant issues arise when attempting to apply this knowledge to clinical practice in the U.S.," she noted. "This study was conducted at only one center in a homogenous population."

Like Dr. Yam, she noted that the effects of atropine and other eyedrops that cause pupil dilation vary based on race and eye color. "The 0.05% concentration may prove too strong for children of other ethnicities," she said.

"Additionally, children in the placebo group were switched to 0.05% atropine in the second year of the study, which will limit the quality of the data gained from future LAMP reports," she said.

"Finally, doctors need to know how much rebound will occur after cessation of the proposed 0.05% optimal dose as compared with the lower concentrations. Future LAMP reports will hopefully shed light on the rebound issue."

"Randomized, controlled, multi-center trials of low-dose atropine are needed in US populations," she concluded.

SOURCE: http://bit.ly/2u6Xfpo Ophthalmology, online December 20, 2019.