chemical injuries and burns to the eyes

Introduction

exposure of a chemical even in powder or dust form, may cause serious long term damage to the eye, particularly if they are alkali as they penetrate deeper into the ocular surface

if possible check the pH of both eyes by pulling down lower lid, place pH strip (NOT urine strips as these apparently over-estimate the alkalinity) in the lower fornix (space between eyelid and globe), and release lid and wait for a few seconds until some tears are absorbed onto strip, then remove and read the pH.
instill a drop of local anaesthetic
all patients should then have immediate first aid copious eye irrigation using 1L normal saline or Hartmann's solution
- following irrigation, wait 10 minutes and re-check pH
- continue above until pH is 7.5 or the same as the unaffected eye
- if pH is still high after 3L irrigation, carefully check eyes for particulate matter (evert and sweep eyelids)
- if pH is normal, re-check 30 minutes later to confirm it has stayed normal.

once pH is normal a formal eye exam should be undertaken with a slit lamp if possible
instill a drop of local anaesthetic
evert and sweep under eyelids to remove particulate matter
examine cornea for haze and epithelial defects using fluorescein stain
NB. a total epithelial defect can be missed if there is no bordering normal epithelium demarcating the staining
if there is staining over the limbus, this may indicate ischaemia of the limbus
- check capillary refill at limbal edge using a cotton bud to compress limbal vessels then observe for reperfusion

grade	clinical features
Grade I	corneal epithelial defect; no corneal haze; no ischaemia
Grade II	mild corneal haze; iris details visible; ischaemia < 1/3rd limbus
Grade III	total corneal loss; stromal haze obscures iris detail; ischaemia 1/3rd - 1/2 limbus
Grade IV	cornea opaque; iris and pupil obscured; ischaemia > 1/2 limbus (eg. “white eye”)

all cases with corneal epithelial defect or reduced vision should be reviewed by an ophthalmology registrar

chloramphenicol eye drops qid
consider flourometholone eye drops qid
if grade II or a toxic exposure (eg. alkali/acid), review every 1-2 days until closure of defect to monitor for complications
advise to return if increasing pain, photophobia or decreased vision

consider admission under ophthalmology for possible debridement of necrotic tissue
chloramphenicol eye drops qid
flourometholone eye drops hourly
ascorbic acid 10% eye drops 2hrly
sodium citrate 10% eye drops 2hrly
homatropine 2% eye drops tds or atropine 1% eye drops tds
preservative free ocular lubricants prn
ascorbic acid 500mg orally qid
ural sachet tds
oral analgesia prn