Progressive lenses and acute anisomentropia

The aim of the poster is to demonstrate that presbyopic patients with acute anisometropia can continue using progressive lenses. Acute or induced anisometropia occurs when a sudden change in the prescription is introduced. A typical example of this occurs following the cataract operation to one eye. The problem arises when the difference in refractive power of both eyes after the operation is 2.00D and more. The difference in lens power can cause the eyes to see different size images and lead to difficulties in fusing them. Additionally, when an image is viewed off axis through the spectacle lens away from the optical centre, a prism is induced by a spectacle lens. Different powered lenses induce different amounts of prism. This unwanted differential prism has the potential to disturb the binocular vision and is especially troublesome when the vertical prism is induced (a very common problem when performing near vision tasks). This publication is based on 3 case study patients with approximately the same amount of acute anisometropia, who were dispensed with progressive lenses: standard corridor, short corridor and progressive lenses with no prism thinning to one lens. While all 3 patients showed relatively good adaptation responses, the patient with short corridor progressive lenses experienced the greatest improvement.