Defining amblyopia: the need for a joint classification.

Recent years have shown an impressive rise in high quality research on amblyopia. Unfortunately, the condition is not sufficiently defined, and consequently different studies have been used different definitions of amblyopia. Aspects in need of consideration include the degree of visual acuity reduction, magnitude of interocular difference in acuity, method of visual acuity testing used, the effect of refractive adaption, the presence of amblyogenic factors, the absence of organic cause and the treat ability of the deficit. Vision scientists worldwide are encouraged to jointly decide on what is, and what is not, amblyopia.