Lazy Eye May Be Reversible in Adults
Key May Be Challenging the Eye, According to Preliminary Tests on Rats
WebMD News Archive
April 30, 2007 -- Amblyopia, or "lazy eye," may be reversible in
adults, according to preliminary tests done on rats.
The experiments were done in Italy by Alessandro Sale, PhD, and colleagues.
Sale works in Pisa, Italy, at the Scuola Normale Superiore.
In amblyopia, one eye is stronger than another. If detected at an early age,
it can be corrected. But amblyopia recovery has proven to be harder in
Sale's team studied 69 adult rats with amblyopia. The researchers sewed the
eyelid on the rats' stronger eye shut, forcing the rats to use their weaker,
The researchers split the rats into two groups. In one group, the rats lived
in pairs in standard cages. The other group of rats lived in what the
researchers call an "enriched environment."
In the enriched environment, groups of at least six rats shared big cages
that had several food sources, a running wheel, and toys, tunnels, stairs, and
shelters that were frequently changed.
Rats in the enriched environment "spend many hours per day exploring the
environment," Sale tells WebMD via email.
The rats in the enriched environment reversed their amblyopia. The effects
lasted at least two weeks after the rats were removed from the enriched
environment, the study shows.
The rats' brains apparently changed to adapt to the constantly changing
enriched environment. Those brain changes may have overridden amblyopia, the
But Sale says it is "absolutely necessary" to note that the effects
"may not apply in the same measure to other species with much higher visual
acuities," including humans.
"Possible applications in humans need further research and suitable
caution, although they are more likely than those of other studies using
pharmacological treatment," Sale says.
The study appears in the advance online edition of Nature