An acute chemical injury is one of the few conditions when virtually all patients voluntarily and immediately disclose the incident. A chemical burn3 is also an exception because the ophthalmologist should not appreciate history-taking as his initial goal; instead, he must "shoot first and ask later": details of injury are asked during or after the initial irrigation. Table 3.1.1 shows the questions the ophthalmologist should raise.
1 It is sensible to use this term rather than "mild," reflecting that with delayed/improper treatment, a mild injury can rapidly become severe (see endophthalmitis classification in Chap. 2.17).
2 i.e., the time between injury and agent removal.
3 The terms "chemical injury" and "chemical burn" are alternatively used in this chapter, referring to the same condition.
Table 3.1.1 Taking a history in a patient with chemical burn
What happened? When did it happen?
What is the name of the agent that caused the injury?
What characteristics (e.g., pH, concentration) does this agent have and how much got onto the eye?
Was this a work-related injury? If yes, was a witness present? Was a report filed?
Was the injury self-inflicted or the result of assault1 ?
Was the eye irrigated after the injury? If yes, with what and for how long?
What therapy has been employed for the injury so far?
How much pain is there now?
How has vision been effected?
It must be emphasized again that these questions are asked only during or after the initial irrigation, not beforehand (see text for more details)
1 Unfortunately, this is not uncommon in certain societies.
If the patient has a chemical injury, the taking of a detailed history should never precede the irrigation.
Pain may be a somewhat misleading symptom. The cornea is involved in nearly all cases, and the pain and severity of the damage are often inversely proportional4.
Severe chemical injuries tend to cause little pain because of the destruction involving the nerve endings. A lack of pain in an eye with severe morphological damage is therefore indicative of a very severe injury with poor prognosis.
4 Similar to that seen with mechanical injuries to the cornea (see Chap. 2.2).
Following the initial irrigation, a penlight is used to search for remnants of the agent5 on the lids, in the palpebral fissure, and in the deep fornices; the latter requires double eversion of the upper lid (see Chap. 2.1). Slit lamp examination follows to determine the damage to anterior segment structures and grade the injury (Table 3.1.2). Since viability of the limbal vascular arcades has prognostic importance, this must carefully be evaluated. The visual acuity and the IOP6 should also be taken. Secondary glaucoma can rapidly develop and cause severe optic nerve damage. Checking the pH of the conjunctival cul-de-sac at the end of the initial rinsing period helps determining when the situation has been stabilized.
After a chemical injury, evaluation and irrigation may have to be alternated: if further rinsing is deemed necessary, the examination is interrupted and continued only after the irrigation has been repeated.
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