Assessing Visual Field in a Visually‐Impaired California Sea Lion ( Zalophus Californianus ) Pre‐ and Post‐ Bilateral Cataract Surgery

ABSTRACT Cataracts, a lens condition that causes clouding of the lens and the progressive obstruction of vision, are common among wild, stranded, and captive pinnipeds. The development of cataracts is attributed to nutritional deficiencies, trauma, age, inadequate access to shade, and/or genetic risk factors. However, despite the well‐documented prevalence of ocular diseases in pinnipeds, there is a paucity of information regarding the efficacy of corrective surgery, which is notably complex due, in large part, to the administration of general anesthesia, requires comprehensive pre‐surgical training and post‐operative monitoring, and incurs a considerable cost to managed care facilities. In this study, the efficacy of the surgical intervention was assessed through visual field tests administered pre‐ and post‐bilateral cataract removal surgery. The subject was a 20‐year‐old female California sea lion ( Zalophus californianus ) with advanced cataracts in both eyes, who was trained to orient towards various light sources to test visual response. Trials were conducted prior to surgical correction and following bilateral cataract removal surgery over a 12‐month period. The rate of successful responses to light stimuli declined significantly prior to surgery and improved after surgery, indicating some degree of post‐operative restoration of visual functioning. These data serve as a foundation for establishing the efficacy of corrective surgery in California sea lions with cataracts and can assist in decision‐making regarding the need and potential outcomes of surgical intervention.