CPT® Code 92145

Corneal hysteresis (CH) is a critical biomechanical property of the cornea that reflects its viscoelastic characteristics. This property is assessed through a specialized procedure that involves applying an external shear force to the cornea using a puff of air, which causes the cornea to flatten, a process known as applanation. Following this, an infrared beam is utilized to monitor the changes in the cornea's shape. The measurement of corneal hysteresis is derived from the difference in air pressure during the applanation process, specifically the pressure required to flatten the cornea when the air is applied and the pressure when the air is released. This measurement is significant as it provides insights into the stiffness or rigidity of the cornea and its ability to withstand intraocular pressure (IOP). Corneal hysteresis is particularly valuable in the context of glaucoma management, as it can offer independent information that aids in both the diagnosis and ongoing management of this condition. Additionally, it may assist in identifying eyes that are at an increased risk for developing keratoconus, a progressive eye disease that affects the cornea's shape and thickness. Furthermore, corneal hysteresis measurements can be used in conjunction with topographic assessments to evaluate the geometric properties of the eye. They also play a role in monitoring the accuracy of tonometric devices, providing a corneal compensated intraocular pressure (IOPcc) measurement that is crucial for comprehensive eye care.