Etiology - Strabismus, commonly known as "cross eyes," can be caused by a myriad of things, such as extraocular muscle imbalances, neurological disorders, refractive errors, genetics, or various forms of vision loss.
Symptoms - Eyes don't move together, noticeable eye drift, squinting/tilting of the head, and overall difficulty with visual tasks.
Details - Strabismus occurs when the eyes don't work in aligned unison when looking at or tracking a singular object. This then leads to noticeable eye misalignment.
Treatment - The best way to treat strabismus is to focus on forcing the eyes to align and work together, but the exact form of strategy can vary widely on a case-by-case basis. Common treatment approaches are corrective lenses, patching of the stronger eye, medication, vision therapy, and strabismus surgery.
Different forms of eye drifting positions noticeably seen in strabismus, especially when tired.
Photo Creds: Cleveland Clinic