What is the purpose of assessing the indirect PLR?

The indirect pupillary light reflex (PLR) is primarily assessed to evaluate the reaction of the non-illuminated eye in response to light shone into the opposite eye. This reflex is important for assessing the integrity of the optic nerve and the pathways involved in the pupillary response. When light is directed into one eye, both pupils should constrict if the neural pathways are functioning normally. Observing the reaction of the non-illuminated eye provides essential diagnostic information about the overall health of the visual and neurological systems of the canine.

The other options mentioned do not relate to the pupillary light reflex. Measuring intraocular pressure is done through techniques specific for glaucoma diagnosis, not through PLR assessment. Color of the sclera may indicate systemic conditions but is unrelated to the pupillary reflex. Assessing corneal reflectivity involves different examinations focusing on the cornea's health and does not evaluate the pupillary light reflex. Thus, the purpose of assessing the indirect PLR is accurately represented by observing the reaction of the non-illuminated eye.