Commotio retinae is a bruise to the retina secondary to blunt trauma. No effective treatment for commotio retinae is known.
It is important to distinguish (on your own; or with the help of an ophthalmologist) this entity from a retinal tear which can also present with decreased visual acuity following ocular trauma but which requires emergent repair.
Source
Albert: Albert & Jakobiec's Principles & Practice of Ophthalmology, 3rd ed.