These finely striated clear lenses are used for evaluating retinal correspondence in patients with eye deviations and in the analysis of anomalous correspondence, suppression, etc. Consists of 2 circular lenses mounted in a flipper.

When you use the penlight, a patient with no suppression will see two diagonal lines crossing above, below, or at the light source. This can be accomplished at a near or far distance. If suppression is present, all or part of one line will not be seen. If the diagonal lines cross at the source when the cover test indicated an ocular deviation, the patient has harmonious, abnormal retinal correspondence.

Penlight has a pupilometer ranging from 2 to 9.