Amblyopie méridienne

Meridian amblyopia or amblyopia induced by astigmatism is a unilateral or bilateral amblyopia resulting from a significant astigmatism that was not corrected during the sensitive period of visual development: unilateral meridian amblyopia is possible with a 0.75 diopter cylindrical anisotropy; bilateral meridian amblyopia is possible in the case of bilateral astigmatism of more than 2 diopters. An oblique axis of astigmatism is more amblyogenic than an orthogonal axis. The prevalence of meridian amblyopia is difficult to assess because the spherical factors are often associated with cylindrical factors, but an asymmetrical astigmatism is clearly a risk factor for amblyopia. Meridian amblyopia would be the consequence notably of a bias in the selectivity in orientation of visual neurones. Treatment of meridian amblyopia resides in total optical correction of the cylindrical ametropia and of the spherical ametropia as well as occlusion of the healthy eye.