Exposure to ionizing radiation may occur with UV light, x-rays, gamma rays, medical imaging equipment, nuclear explosions, and radioisotopes. The level of exposure is related to the amount of energy in the ionizing radiation, the type of rays emitted, the duration of exposure, and the patient’s proximity to the ionizing source. Tissue destruction may result from direct killing of cells, cellular DNA changes that produce lethal or other mutations, or radiation damage to blood vessels with secondary ischemic necrosis.
Ionizing radiation can damage the conjunctiva, cornea, and occasionally the lacrimal glands. Conjunctival edema occurs acutely, often followed by scarring, shrinkage, loss of tear production, and alterations in conjunctival blood vessels with telangiectasia. Necrosis of the conjunctiva and underlying sclera can occur if radioactive material (or a radiomimetic agent such as mitomycin C) is embedded in the conjunctiva. Punctate corneal epithelial erosions are noted acutely. Explosions involving ionizing radiation may lead to perforation of ocular tissues with immediate radiation necrosis.
The first step in management of acute radiation injury is removal of all foreign bodies. Poor wound healing is a hallmark of ionizing radiation injuries. Late complications are related to decreased tear production, loss of corneal sensation, sloughing of corneal epithelial cells, and failure of the cornea to heal. Secondary microbial keratitis, vascularization, and ocular surface disease can result from dry eyes and compromised epithelial cells. The use of artificial tears or a bandage contact lens may help stabilize the ocular surface in mild cases. More severe cases may require tarsorrhaphy and/or tissue adhesive. If there is recurrent epithelial breakdown despite these measures, significant conjunctival scarring typically precludes the use of a conjunctival flap from that eye. If the fellow eye has not been injured, a contralateral autologous conjunctival flap may be helpful. Alternatively, an amniotic membrane transplant, limbal stem cell transplant, or mucous membrane graft may be employed. The visual prognosis associated with penetrating keratoplasty or limbal stem cell transplantation in these situations is guarded because of the severely compromised ocular surface.
Excerpted from BCSC 2020-2021 series: Section 10 - Glaucoma. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.