Question

Describe three ways by which prisms are used in the assessment of squint and heterophoria

Answer 1

1. Base-out prisms for visual comfort in patients with non-accommodative esophoria.

2.Prismsay be used for postoperative overcorrection of exodeviation. It is sometimes used preoperatively to enforce bifoveal stimulation.

3.Prisms in glasses are also tried in selective cases of hyperphoria. The prism is prescribed with the apex toward the direction of hyperphoria to correct one-half or at the most two-third of heterophoria only.

4. Prism cover test is used for measuring angke od deviation on near and far distance.