The etiology, diagnosis, sequelae, and management of ocular hypotony are discussed in this review. Hypotony from decreased production of aqueous is often due to inflammation, medications, or proliferative vitreoretinopathy. Hypotony from aqueous loss may be external, such as following surgery or trauma, or internal, as in cyclodialysis cleft or retinal detachment. Treatment of hypotony is most effective if the underlying cause can be addressed, either surgically or medically. Marked improvement in vision may be achieved if hypotony is reversed.