Convergence Insufficiency and Square Wave Jerks in PSP

This is a 70yowoman with progressive supranuclear palsy with complaints of difficulty reading. Her husband noticed that she would frequently close one eye when attempting to read, and words were not clear on the page, and this would in fact improve by covering one eye. On her exam, she had a 1 prism diopter (PD) esodeviation with Maddox rod testing at distance (difficult to appreciate subtle refixation saccades with alternate cover testing due to her square wave jerks), and with alternate cover testing at near, there was a 10 PD exotropia. Additionally, her near point of convergence was about 20 cm (normal is 10 cm), and her convergence amplitude was 4 PD (base out prism normal is 15 PD). Convergence insufficiency is common following concussion, TBI or with parkinsonism. Square wave jerks are common in PSP, and hers are shown here as well.