Testing Visual Function by Assessment of the Optomotor Reflex in Glaucoma

Optomotor response/reflex (OMR) is a fast and efficient first-in-line visual screening method, especially for rodents. It has the potential to evaluate both the scotopic and photopic visions of nonrestrained animals through tracking head movement, providing a quantitative estimate of visual functions. In restrained animals, optokinetic response (OKR), compensatory eye movements for visual shifts in the surroundings, is utilized. Both OMR and OKR capitalize on an individual's innate reflex to stabilize images for the purpose of capturing clear vision. The two reflexes have similar reliability when evaluating stimulus luminance, contrast, spatial frequency, and velocity. They have emerged as powerful tools to evaluate the efficacy of pharmacological treatments and phenotypes of subjects undergoing study. With OMR and OKR accurately assessing visual acuity (VA) as well as contrast sensitivity (CS), the gold standards for measuring clinical vision, they provide reliable and easily accessible results that further eye and brain research. These methods of sight evaluation have been used in multiple animal models, particularly mice and zebrafish. Through OMR assays, these animal models have been utilized to investigate retinal degenerative diseases, helping researchers differentiate between worsening stages. Alongside tests such as optical coherence tomography (OCT), OMR provides confirmation of visual status, where increased OMR function often correlates with improved visual status. OMR has continued to be used outside of glaucoma in various retinal diseases, such as retinitis pigmentosa (RP), diabetic retinopathy, and age-related macular degeneration.In this chapter, we will introduce the concept and application of visual stimulus-induced head or eye reflex movement in different animal species and experimental models of eye diseases, such as glaucoma and other neurodegenerative disorders, and in patients with glaucoma.