Atropine is a drop that has been used in eye care for treatment of amblyopia (lazy eye) and other conditions for many, many years.
With the alarming increase in the number of children with myopia and high myopia, it has been researched as a tool for slowing the progression of myopia and has demonstrated strong and effective results. Several studies (ATOM, ATOM2) showed that atropine was effective at slowing refractive changes even at very low concentrations which rarely caused the side effects that limited its use before.
Atropine therapy can be a good choice for those children that are too young or otherwise unable to utilize other options of myopia control, however, it does still require the use of daytime vision correction. It has also been shown to work well as combination therapy along with soft multifocal lenses or ortho-K for patients that have shown higher rates of change.
The more common side effects are pupil dilation causing light sensitivity and trouble focusing on near work. Many children have no problems at all, your doctor will discuss these issues along with other pros and cons during your consultation.