Saturday, April 4, 2009

10.1 Truth or Consequences

Drug companies in Taiwan probably have sold the most atropine eyedrops than anywhere in the universe. You might wonder what it is used for. It turns out that atropine drops and other cycloplegics are used to control the progression of school myopia.

There has been a long history of cycloplegics used for this purpose; however, it has never gained any popularity elsewhere. In fact, atropine in particular is prescribed, if at all, only for the treatment of amblyopia. As it does appear as efficacious as eye patching; although the treatment is short-term. In contrast, atropine treatment for myopia goes on for years.

Since so many myopic children in Taiwan are treated with cycloplegics and who do not wear optical corrections in school, teachers are running out of front-row seats for these children and start to question this practice.

Do the cycloplegics work? Yes, if one considers less myopia progression a success and a goal by itself. What about the ultimate purpose? Unclear. Because cycloplegics do not reverse myopia, which merely slow down the progression. So, by late teens or early 20s when the myopization process naturally stops, patients are still left with moderate to high myopia. The atropine treatment appears to have based on the assumptions that (1) all myopia cases can become degenerative myopes and that (2) high myopia equals ocular diseases developed later in life such as glaucoma and various retinal integrity issues. And by lowering the degree of myopia, these diseases can be avoided. Unfortunately, so far there is no hard evidence to support this proposal. Perhaps a certain segment of the myopic population can indeed benefit from cycloplegia; again, there is no evidence.

And the downside of long-term atropine treatment? Let's see, cycloplegia causes loss of accommodation and prolonged pupil dilation, allows large amounts of UV into the eye, and potentiates chronic narrow-angle glaucoma. Worse, it is not known how long the treatment can continue without irreversible paralysis of ciliary and iris muscles.

There is something amiss here.