Causes of initial visual loss following blunt ocular injuries: an experimental study.

We have investigated in anaesthetised pigs the electrical responses of the retina to light after blunt injuries to the eye. Retinograms, cortical visual evoked responses and intraocular pressures were recorded before and after non-perforating mechanical trauma of sufficient severity to produce traumatic retinal opacification. After injury, applanation pressures rose up to 34 mm. Hg above normal, reaching peak values 4 to 12 minutes after trauma and returning to pre-trauma levels after about 45 minutes. These pressure changes were not responsible for the immediate abolition of the B wave of the retinogram or of the cortical visual evoked responses which occurred after trauma, but increases of intraocular pressure modified the recovery pattern of the visual evoked response.