Final answer:
Anisocoria is the term for when a patient has different sizes of pupils. It can be a sign of neurological issues or normal variation, linked to the autonomic control of the eye reacting to various stimuli such as light levels.
Step-by-step explanation:
The term for the presence of different sizes of a patient's pupils is anisocoria. This condition can be a normal variation or a sign of a medical issue. When the sympathetic system is activated, norepinephrine binds to adrenergic receptors in the radial fibers of the iris smooth muscle causing mydriasis, or pupillary dilation. This can be mimicked by phenylephrine drops applied to the eye in a medical setting. In contrast, miosis refers to pupillary constriction, which can be induced by the release of acetylcholine (ACh) onto the smooth muscles of the iris.
An additional illustration of how eye conditions reflect neurological activity is the case of bilateral hemianopia, the loss of lateral peripheral vision due to a growth pressing against the optic chiasm, illustrating that not all visual field deficits are directly tied to the visual system itself. In a less pathologic context, the relative size adjustment of the pupil in response to light exposure is part of the normal autonomic control of pupillary size, such as when pupils dilate in the dark to allow more light to enter and constrict in bright light to reduce light exposure.