Radiation Injuries Ionizing Radiation

Etiology: Ionizing radiation (neutron, or gamma/x-ray radiation) have high energy that can cause ionization and formation of radicals in cellular tissue. Penetration depth in the eye varies with the type of radiation, i.e., the wavelength, resulting in characteristic types of tissue damage (Fig. 18.13). This tissue damage always manifests itself after a latency period, often only after a period of years (see also Symptoms and clinical picture). Common sites include the lens (radiation cataract) and retina (radiation retinopathy). This tissue damage is usually the result of tumor irradiation in the eye or nasopharynx. Radiation disorders have been observed in patients from Hiroshima and Nagasaki and, more recently, in Chernobyl.

Symptoms and clinical picture: Loss of the eyelashes and eyelid pigmentation accompanied by blepharitis are typical symptoms. A dry eye is a sign of damage to the conjunctival epithelium (loss of the goblet cells). Loss of visual acuity due to a radiation cataract is usually observed within one or two years of irradiation. Radiation retinopathy in the form of ischemic retinopathy with bleeding, cotton-wool spots, vascular occlusion, and retinal neovasculariza-tion usually occurs within months of irradiation.

18.6 Indirect Ocular Trauma: Purtscher's Retinopathy Possible radiation damage to the eye. -

Ultraviolet

Radiation

Radiation

keratoconjunctivitis

cataract

retinopathy

Ultraviolet radiation Infrared radiation Visible li

Gamma radiation

Fig. 18.13 The penetration depth of radiation in the eye varies according to wavelength. Therefore, each radiation injury causes characteristic tissue damage.

Treatment and prophylaxis: Care should be taken to cover the eyes prior to planned radiation therapy in the head and neck. Radiation cataract may be treated surgically. Radiation retinopathy may be treated with panretinal photocoagulation with an argon laser.

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