Injuries Due to Physical Agents

18.5.1 Ultraviolet Keratoconjunctivitis

Etiology: Injury from ultraviolet radiation can occur from welding without proper eye protection, exposure to high-altitude sunlight with the eyes open without proper eye protection, or due to sunlight reflected off snow when skiing at high altitudes on a sunny day. Intense ultraviolet light can lead to ultraviolet keratoconjunctivitis within a short time (for example just a few minutes of welding without proper eye protection). Ultraviolet radiation penetrates only slightly and therefore causes only superficial necrosis in the corneal epithelium. The exposed areas of the cornea and conjunctiva in the palpebral fissure become edematous, disintegrate, and are finally cast off.

H Ultraviolet keratoconjunctivitis is one of the most common ocular injuries.

Symptoms and diagnostic considerations: Symptoms typically manifest themselves after a latency period of six to eight hours. This causes patients to seek the aid of an ophthalmologist or eye clinic in the middle of the night, complaining of "acute blindness" accompanied by pain, photophobia, epiphora, and an intolerable foreign-body sensation. Often severe blepharospasm will be present. Slit-lamp examination will require administration of a topical anesthetic. This examination will reveal epithelial edema and superficial punctate keratitis or erosion in the palpebral fissure under fluorescein dye (see Fig. 18.5).

U The topical anesthetic will completely relieve symptoms within a few seconds and allow the patient to see clearly and open his or her eyes without pain. Under no circumstances may the patient be allowed access to this anesthetic without medical supervision. Uncontrolled habitual use suppresses the pain reflex (eye closing reflex), which could result in incalculable corneal damage.

Treatment: The "blinded" patient should be instructed that the symptoms will resolve completely under treatment with antibiotic ointment within 24 to 48 hours. Ointment is best be applied to both eyes every two or three hours with the patient at rest in darkened room. The patient should be informed that the eye ointment will not immediately relieve pain and that eye movements should be avoided.

18.5.2 Burns

Etiology: Flaring flames such as from a cigarette lighter, hot vapors, boiling water, and splatters of hot grease or hot metal cause thermal coagulation of the corneal and conjunctival surface. Because of the eye closing reflex, the eyelids often will be affected as well.

Injuries due to explosion or burns from a starter's gun also include particles of burned powder (powder burns). Injuries from a gas pistol will also involve a chemical injury.

Symptoms and diagnostic considerations: Symptoms are similar to those of chemical injuries (epiphora, blepharospasm, and pain).

A topical anesthetic is administered, and the eye is examined as in a chemical injury. Immediate opacification of the cornea will be readily apparent. This is due to scaling of the epithelium and tissue necrosis, whose depth will vary with the severity of the burn. In burns from metal splinters, one will often find cooled metal particles embedded in the cornea.

Treatment: Initial treatment consists of applying cooling antiseptic bandages to relieve pain, after which necrotic areas of the skin, conjunctiva, and cornea are removed under local anesthesia. Foreign particles such as embedded ash and smoke particles in the eyelids and face are removed in cooperation with a dermatologist by brushing them out with a sterile toothbrush under general anesthesia. This is done to prevent them from growing into the skin like a tattoo. Superficial particles in the cornea and conjunctiva are removed under local anesthesia together with the necrotic tissue. The affected areas are then treated with an antibiotic ointment.

Prognosis: The clinical course of a burn is usually less severe than that of a chemical injury. This is because burns, like acid injuries, cause superficial coagulation. Usually they heal well when treated with antibiotic ointment.

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