What does the pupillary light response (PLR) assess?

The pupillary light response (PLR) assesses the reaction of the pupil to light. This reflex involves a response where the pupil constricts when exposed to light; this is an important assessment technique used in both veterinary and human medicine to evaluate the function of the optic nerve and the pathways involved in reflexive reactions.

When light enters the eye, it stimulates photoreceptors in the retina, sending signals through the optic nerve to the brain and back to the pupil via the parasympathetic nervous system, causing it to constrict. This response helps to examine the integrity of the sensory and motor pathways in response to light, which can provide insights into neurological functioning.

The other choices are not related to the pupillary light response. Determining eye color does not involve the pupil's reaction but rather the pigmentation in the iris. Measuring corneal thickness is a separate diagnostic procedure for conditions like glaucoma and does not assess pupil reflexes. Evaluation of scleral health focuses on the condition of the white part of the eye, often related to systemic health issues, rather than the light response of the pupil. Thus, understanding PLR is crucial for evaluating ocular and neurological health in canine patients.