Young Children Need Higher Atropine Concentrations to Curb Myopia

By Marilynn Larkin

January 20, 2021

NEW YORK (Reuters Health) - Younger children require higher concentrations of atropine to achieve similar reductions in myopia progression as older children on lower concentrations, researchers say.

"Low-concentration atropine is an emerging therapy for myopia control, but the treatment response varies among children (and) the determining factors were not certain before our study," Dr. Jason Yam of The Chinese University of Hong Kong told Reuters Health by email.

"We have identified an age-dependent effect in each atropine treatment group - the younger the age, the poorer response," he said. "At the same time, (we saw) a concentration-dependent response in each age group - the higher the concentration, the better the response."

"Therefore," he said, "a higher concentration - i.e., 0.05% - should be administered as a starting dosage for younger children, given that they have a greater risk of myopia progression, (and treatment) should be more aggressive to reduce the burden of high myopia."

The main reason for the discrepancies in response is that myopia progression is age-dependent, he noted. "Younger myopic kids tend to progress faster than older children. This means that a myopic child at age six will progress faster than a myopic child at age eight, and much faster than a myopic child at age 10."

As reported in Ophthalmology, Dr. Yam and colleagues did a secondary analysis of the two-year results of the randomized Low-concentration Atropine for Myopia Progression (LAMP) study. Participants were 350 children stratified by age (4-6, 7-9, and 10-12) and gender, originally assigned to receive 0.05%, 0.025%, 0.01% atropine or placebo once daily in both.

In the second year, the placebo group was switched to 0.05% atropine.

Factors evaluated included age at treatment, gender, baseline refraction, parental myopia, time outdoors, diopter hours of near work, and treatment compliance.

Over two years, younger age was the only factor associated with spherical equivalent progression and axial length elongation in all three treatment groups. As Dr. Yam noted, the younger the age, the poorer the response.

At each year of age from four to 12 across treatment groups, higher atropine concentrations showed a better treatment response, following a concentration-dependent effect.

Specifically, the mean progression of six-year-old children at 0.05% atropine (-0.90 diopter) was similar to that of eight-year-olds at 0.025% atropine (-0.89D), and 10-year-olds at 0.01% (-0.92D).

All atropine concentrations were well tolerated at all ages.

Dr. Yam said, "One remaining question is the rebound phenomenon after cessation of atropine 1%, 0.5%, 0.1%, and 0.01%, as observed in (previous) studies. We aim to evaluate (1) efficacy of 0.05% atropine, 0.025% atropine, and 0.01% atropine over three years; (2) whether treatment should be stopped after two years; and (3) the rebound phenomenon... after cessation of treatment."

Dr. Christopher Starr, an ophthalmologist at Weill Cornell Medicine and NewYork-Presbyterian in New York City, commented in an email to Reuters Health, "The use of low-dose atropine in children to reduce progression of myopia is a fairly recent development in the field. While it has been shown to be effective in multiple studies, the optimal dosage, age of initiation and duration of treatment are still being optimized. Good studies like this one... are helping to better define our treatment protocols."

"We believe that reduced outdoor time (i.e., natural light / sun exposure) is an independent risk factor for childhood myopia, but interestingly that was not detected in this study," he noted. "The investigators cite a validated questionnaire and potential recall bias as possible reasons. The COVID-19 pandemic has led to even more time indoors for our children, which may lead to even higher rates of childhood myopia in the near future."

SOURCE: Ophthalmology, online January 7, 2021