Final answer:
The pupil response to light indicates the health of the optic and oculomotor nerves. A lack of pupil contraction in response to light may signify potential nerve damage. The pupillary light reflex involves both autonomic and neural pathways.
Step-by-step explanation:
If one or both pupils are dilated, particularly if they don't react to light, the child may have an issue with the neural pathways involved in the pupillary light reflex. Normally, when light is shined into one eye, there is a constriction of that pupil, as well as the opposite pupil -- this is a result of the reflex being bilateral. The optic nerve and the oculomotor nerve play critical roles in this reflex; thus, any abnormalities in pupil response could indicate damage to one of these nerves.
If shining light in one eye causes no change in pupillary size but shining light in the opposite eye elicits a normal response in both eyes, the issue is likely associated with the optic nerve on the side where the response to light is absent. If only one pupil reacts to light regardless of which eye is stimulated, the problem could be with the oculomotor system. The significance of the pupillary reflex lies in the autonomic control exerted by the sympathetic and parasympathetic systems in response to varying light levels.