Radiation injuries encompass damage caused by various types of radiation in the electromagnetic spectrum, such as microwaves, infrared rays, visible light, ultraviolet rays, X-rays, and gamma rays. Exposure to radiation such as neutron or proton beams can also result in this type of injury.
Visible Light Injury
Thermal and photochemical effects can damage the macula, as seen in "solar retinopathy" caused by improper observation of a solar eclipse. The impact on vision varies, with severe cases presenting symptoms such as central scotomas, distorted vision, and headaches. Visual acuity may decline to levels around 0.08–0.1. Initial examination within a few days may reveal yellowish-white spots at the central fovea, which later develop into reddish spots with pigment halos. After two weeks, small, reddish, lamellar holes may appear at or near the central fovea. Mild cases may recover fully or partially within 3–6 months, but severe injuries can lead to permanent vision loss. Prevention remains crucial, and protective tinted glasses are necessary in strong light environments.
Retinal photic damage can be caused by strong light sources, resulting in paracentral scotomas in the visual field. Deep yellowish-white lesions can appear next to the central fovea and later develop a mottled appearance, with imaging showing increased fluorescence. Mechanical, thermal, and photochemical effects of lasers can cause retinal inflammation and scarring, underscoring the importance of protective measures. Recently, cases of temporary or permanent visual impairment caused by unqualified commercial laser pointers have been noted, highlighting the need for public awareness and regulatory enforcement.
Ultraviolet Radiation Injury
Ultraviolet radiation injuries, also known as "electric ophthalmia" or snow blindness, can result from exposure to welding arcs, high altitudes, snowfields, or water surface reflections. Ultraviolet radiation exerts photochemical effects on tissues, leading to protein coagulation and denaturation, with necrosis and sloughing of corneal epithelium. Symptoms typically develop 3–12 hours after exposure and may include severe foreign body sensation, stinging pain, photophobia, tearing, blepharospasm, mixed conjunctival hyperemia, and punctate corneal epithelial erosions visible under fluorescein sodium staining. Symptoms usually subside or resolve entirely within 24 hours. UV-B radiation has also been closely linked to the development of age-related cataracts.
Figure 18 Electric ophthalmia
Fluorescein sodium staining under cobalt blue light shows diffuse punctate staining of the right corneal epithelium.
Management involves symptomatic treatment to alleviate pain, with antibiotic eye ointments applied to prevent infection. Eye drops or gels that promote corneal epithelial healing may also be used. Protective face shields or glasses are essential preventive measures.
Ionizing Radiation Injury
Exposure to ionizing radiation from sources such as X-rays, gamma rays, neutron beams, or proton beams can lead to conditions such as radiation-induced cataracts, radiation retinopathy or optic neuropathy, keratitis, or iridocyclitis. This type of injury is often associated with radiotherapy for tumors. Ionizing radiation exposure can damage retinal vasculature, with external irradiation or the use of local radioactive plaques (doses of 30–36 Gy, although 15 Gy has been reported to cause damage). Such injuries typically result in progressive microvascular damage resembling diabetic retinopathy, occurring 4 months to 3 years post-exposure. Cases may range from asymptomatic to presenting with vision decline. Examination findings may include nerve fiber layer infarcts, retinal hemorrhages, microaneurysms, vascular sheathing, capillary dilation, exudates, non-perfusion areas, and neovascularization. The visual prognosis depends on macular involvement. Treatment options include localized or extensive laser photocoagulation. Acute radiation optic neuropathy can also lead to vision loss.