chemical injuries

Question 1

what is Roper hall grade 1?

Answer 1

• cornea clear
• no limbus ischaemia
• good prognosis

Question 2

what is Roper hall grade 2?

Answer 2

• Corneal haze, iris details visible
• <1/3 limbus ischemia
• good prognosis

Question 3

what is Roper hall grade 3?

Answer 3

• Total epithelial loss, stromal haze, iris details obscured
  -1/3 - 1/2 limbus ischemia
  guarded prognosis

Question 4

what is Roper hall grade 4?

Answer 4

• Opaque
• > 1/2 limbus ischemia
• poor prognosis

Question 5

what are the investigations for chemical injuries?

Answer 5

• Fluorescein stain for epithelial defects 🡪 if missed and untreated, can result in symblepharon, ankyloblepharon, loss of fornix
• Check IOP
• Attempt fundoscopy

Question 6

what is the management for chemical injuries?

Answer 6

STAT copious irrigation with normal saline (2L first, then assess) (first aid!)

• Start flushing directly into eye, asking patient to look in different directions while irrigating.
• Flush until no more offending agent is seen (no objective cut-off, may use 1-2 bags of normal saline, use litmus paper to test pH – should be close to neutral).

If cement particles still in situ, use a moist cotton swab and/or forceps and remove as much as possible

Prevent infection

• Topical antibiotics
• Occasionally consider tetracycline (a collagenase inhibitor)

Improve healing

• Eye lubricants
• +/- PO vitamin C 100 mg OM (vitamin C is cofactor in rate limiting step of collagen synthesis)

Reduce inflammation

• Dexamethasone (preservative free) for 7-10 days
• EDTA (chelating agent, chelates Ca2+ required for collagenase activity)

Relieve pain

• PO analgesia
• For cycloplegia: atropine, homatropine

Control IOP

Frequent review to ensure proper healing occurs (which may take weeks)

Question 7

what are the complications?

Answer 7

Corneal healing with scarring (corneal scar = localised, well-circumscribed corneal opacity)

Cornea may remain hazy permanently, and if this scarring is central (obstructing visual axis) 🡪 poor prognosis of regaining vision 🡪 consider corneal transplant

Non-healing epithelial defects

Persistent inflammation, glaucoma 2’ to damage to aqueous outflow pathway/trabecular meshwork (rise in IOP), or 2’ to steroid S/E

Corneal decompensation

Entropion 2’ to scarring on eyelids