Acid burns

Acid burns are less serious than alkali burns. Common
acids responsible for burns are: sulphuric acid,
hydrochloric acid and nitric acid.
Chemical effects. The strong acids cause instant
coagulation of all the proteins which then act as a
barrier and prevent deeper penetration of the acids
into the tissues. Thus, the lesions become sharply
demarcated.
Ocular lesions
1. Conjunctiva. There occurs immediate necrosis
followed by sloughing. Later on symblepharon is
formed due to fibrosis.
2. Cornea. It is also necrosed and sloughed out.
The extent of damage depends upon the
concentration of acid and the duration of contact.
In severe cases, the whole cornea may slough
out followed by staphyloma formation.
Grading of chemical burns
Depending upon the severity of damage caused to
the conjunctiva and cornea, the extent of chemical
burns may be graded as follows (Table 17.1):
Treatment of chemical burns
1. Immediate and thorough wash with the available
clean water or saline.
2. Chemical neutralization. It should be carried out
when the nature of offending chemical is known.
For example, acid burns should be neutralized
with weak alkaline solutions (such as sodium
bicarbonate) and alkali burns with weak acidic
solutions (such as boric acid or mix)
Ethylenediamine tetra acetic acid (EDTA) 1%
solution can also be used as neutralizing agent.
3. Mechanical removal of contaminant. If any
particles are left behind, particularly in the case
of lime, these should be removed carefully with
a swab stick.
4. Removal of contaminated and necrotic tissue.
Necrosed conjunctiva should be excised.
Contaminated and necrosed corneal epithelium
should be removed with a cotton swab stick.
5. Maintenance of favourable conditions for rapid
and uncomplicated healing by frequent application
of topical atropine, corticosteroids and antibiotics.
6. Prevention of symblepharon can be done by
using a glass shell or sweeping a glass rod in the
fornices twice daily.
7. Treatment of complications
i. Secondary glaucoma should be treated by
topical 0.5 percent timolol instilled twice a day
along with oral acetazolamide 250 mg 3-4 times
a day.
ii. Corneal opacity may be treated by
keratoplasty.
iii. Treatment of symblepharon