Anisocoria (unequal pupil size) can arise from various physiological or pathological conditions. Primary causes include lesions in the eye or head region, migraines, and tumors. Additionally, other factors that can lead to anisocoria include:

* Neurological Causes: Horner's syndrome (a disorder of the nervous system), nerve palsy, brain aneurysms, brain tumors, and certain types of cancer.
* Eye and Head Trauma: Impacts and injuries to the eye or head.
* Medications and Treatments: Side effects of eye drops or certain medical drugs, and post-surgical complications.
* Other Health Issues: Various health problems such as glaucoma (high eye pressure), inflammations inside the eye, and severe migraine-type headaches.

A comprehensive evaluation is essential to accurately determine the underlying cause of anisocoria. Based on this diagnosis, the treatment plan will vary and be tailored specifically to the underlying condition.