(2) When the retina is exposed to pulsed laser energy, the heat cannot be carried away quickly enough by thermal conduction. The tissue is superheated and undergoes an explosive change of state, creating shock waves which mechanically disrupt tissue and spread the area of damage. If more energy is introduced, the injured area will become larger. The mechanical force produced can blow a hole through the retina and choroid, resulting in hemorrhage and may lead to severe visual loss. The blood can collect beneath the photoreceptor cell layer of the retina, disturbing its contact with the retinal pigment epitheliums resulting in retinal detachment (Figure 4). This subretinal hemorrhage can result in the death of the photoreceptor cells and a scotoma that is much larger than the thermal burn or mechanical disruption. The blood may also move into the vitreous through the disrupted retina, where it may obstruct the passage of light through the eye (Figure 5). Extensive or centrally located hemorrhage can produce a significant loss of vision. Blood in the vitreous is absorbed very slowly, but in most cases it is absorbed. The visual impairment remains as long as the blood persists; vision may improve to normal with resorption of the blood. Persistent vitreal hemorrhage may be removed by a complicated
from : http://www.globalsecurity.org/military/library/policy/army/fm/8-50/INTRO.htm