Supposing somebody suffers a hyphema, but gets to the er in like 20 minutes, can they be expected to regain full vision?

Emergency: Anyone one with a hyphema needs emergency evaluation by an ophthalmologist. Any delay can have severe vision consequences.

Very possible. : Hyphemas require urgent assessment by an ophthalmologist as they may result in permanent visual impairment. A long-standing hyphema may result in corneal and other eye tissue damage. Blood accumulation may also cause an elevation of the intraocular pressure. Most small, uncomplicated hyphemas resolve within a week. The key is to be under the careful care of an ophthalmologist as soon as possible.