Heat is a primary cause of inflammation and stromal protease expression and can lead to collagen melting if severe. Rapid-reflex eyelid closure, Bell phenomenon, and reflex movement away from the source of intense heat usually limit damage to the globe from flames. Burns from molten metal that stays in contact with the eye are more likely to cause corneal injuries that result in permanent scarring.
Curling irons, cigarettes, and hot liquids splashing into the eye, especially during cooking, are common household causes of corneal burns (Fig 14-10). These burns are usually limited to the epithelium and generally require only a brief period of antibiotic and cycloplegic therapy.
Figure 14-10 Cigarette burn on the cornea.
(Courtesy of Woodford S. Van Meter, MD.)
Ocular electrical injury may be caused by heat or electric current. Electric current can eventually cause corneal epithelial erosion.
The primary objectives of therapy for burns caused by heat are the following:
prevent secondary corneal inflammation, ulceration, and perforation from infection or from exposure caused by eyelid damage
minimize eyelid scarring and resultant malfunction
A cycloplegic agent can help relieve discomfort from ciliary spasm or iridocyclitis. Prophylactic antibiotics (topical and/or systemic) can help prevent infection of burned eyelids and/or reduce the chances of infectious corneal ulceration. Limited debridement of devitalized tissues and granulation tissue, used with full-thickness skin grafts and tarsorrhaphy, helps minimize eyelid scarring and ectropion. Burned ocular tissue can be protected temporarily by covering the eye with a lubricant and a piece of sterile plastic wrap. Topical corticosteroids help suppress any associated iridocyclitis, but they can also inhibit corneal wound healing and must be used with caution and, in general, for short periods.
Transient corneal stromal edema induced by cold has been reported in a variety of settings, including prolonged exposure to cold when skiing or mountain climbing. Cold temperatures adversely affect the Na+,K+-ATPase pump function of the endothelial cells and render it less effective. Individuals with Raynaud disease and those with cranial nerve V (trigeminal) dysfunction may be especially susceptible. Research suggests that sensory denervation of the eye increases the susceptibility of the endothelium to cold temperatures.
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.