CATS tonometer for Ocular Hypotony

Prospective, open-labeled, randomized, controlled, multicenter study at two clinical investigative sites in Tucson, Arizona. The subjects will undergo intraocular pressure measurement with the CATS tonometer prism and the Goldmann applanation tonometer prism (GAT). Seventy-five (75) Subjects 18 and older and will be enrolled. Subjects will be screened based on standard of care vision examination at the clinical investigation sites. All subjects will undergo a standard ophthalmic exam and informed consent. IOP will be measured using a Goldmann tonometer armature with both the standard flat GAT prism and the modified curved CATS prism alternately inserted. The only additional measurement is central corneal thickness (CCT) which is used to correct for one of the corneal biomechanical errors seen in the GAT prism and is currently standard of care.