Belle, a three-year-old, is brought into the paediatric emergency department rubbing a red, watering eye. Belle’s father explains that 45 minutes ago she was found screaming on the kitchen floor with a box of Ariel All-in-1 laundry pods next to her. She had detergent on her hands and in her hair and refused to open her right eye. Her father read the warning label which states ‘Danger. Causes serious eye damage’ and is very anxious about whether she will see again. He rinsed her hands and hair and attempted to wash out the eye for a few minutes but isn’t sure if it was effective.
Don’t forget the 3 I’s:
IRRIGATE, IRRIGATE and IRRIGATE
Chemical eye injuries need urgent irrigation, before undertaking a full history or examination. This is one of the two critical factors in determining the visual outcome.
Eye injuries are a leading cause of non-congenital unilateral blindness in children. Up to 90% of cases are thought to be preventable through a combination of protective eyewear and the education of supervising adults.
In the POTS2 study, a prospective observational study of all children under 15 admitted to hospital with ocular trauma over a one year period in Scotland, 1% of the 93 children in the study had a chemical eye injury. In general, only 5% of children with ocular trauma require hospital admission. A 2016 cross-sectional analysis of the US Nationwide Emergency Department system found that children aged one to two years are at significantly higher risk for ocular chemical injuries than any other group (28.61 and 23.49 per 100,000 population for one- and two-year-olds, respectively). Ocular chemical burns were most common among 18- to 64-year-olds, but at a rate half that of infants (13.28 per 100,000 population).
Acids and alkalis
Alkalis are responsible for the most severe chemical injuries. Because acids instantly precipitate tissue proteins, a barrier is formed which prevents further ocular penetration. For this reason, acid burns are often well-demarcated and superficial – this is called coagulative necrosis.
Alkalis, on the other hand, can cause extensive and penetrating eye injuries due to their ability to saponify fatty acids in the cell membrane, destroying cellular structures, extract water from cells, leading to necrosis, and combine with lipids to form compounds that soften and gelatinise the ocular surface – liquefactive necrosis. This is somewhat similar to other burns, where viscous, sticky liquids continue to penetrate deeper into the dermal layers, even over days.
The severity of chemical eye injuries ranges from trivial, transient conjunctival irritation to sudden and complete visual loss. Signs and symptoms include:
- Blurred vision
- Foreign body sensation
- Blepharospasm (abnormal, involuntary blinking or spasm of the eyelids)
- Cloudy cornea
- Red-eye. NB. Similar to other burns, in severe cases ischaemia (in this case of the conjunctival vessels) may mean that the eye does not appear red
- Cloudy cornea
Based on an estimate of limbal involvement in clock hours and the percentage of conjunctival involvement, the Dua classification is the most recent classification used to grade chemical burns.
Ocular pH testing
The normal pH of the eye is 7.4. Irrigation should continue until the ocular pH remains neutralised 10 minutes after stopping the irrigation after instillation of local anaesthetic drops, or a minimum of 2L of 0.9% sodium chloride or Hartmann’s solution (if neither are available, use water) is administered within 20-30 minutes. Once the pH has neutralised, the eye can be examined.
Technique: ocular pH testing
- Use the uninjured eye (or your own eye) as a control pH test
- Use litmus or pH paper – keep in a dark dry bottle so it retains its colour
- Instil Proxymetacaine 0.5% local anaesthetic drops
- Momentarily stop the irrigation and gently place the paper in the inferior conjunctival fornix – as you pull down the lower lid, this is the junction where the white curved surface of the eye meets the red conjunctiva of the lower lid
- The colour should change immediately. Interpret using the reference chart
NB. The colour of the pH or litmus paper fades rapidly with time – don’t forget to make a note of it!
Don’t forget the 3 I’s: IRRIGATE, IRRIGATE and IRRIGATE. Use either isotonic saline or Hartmann’s solution but if you have neither, use water. Aim to irrigate 2L within 20-30 minutes or continue until pH remains neutralised 10 minutes after irrigating. Up to 20L or more may be required to restore the pH to physiological levels. Make sure you evert both the upper and lower eyelids to make sure there is no remaining chemical material.
Local anaesthetic drops, e.g. tetracaine hydrochloride or proxymetacaine, can be used to help keep the eye open during irrigation. If the child’s old enough, warm them that it will sting briefly. Proxymetacaine stings less, but tetracaine produces more profound anaesthesia. If you’re still irrigating, add a drop every 5 minutes, as this will also be washed away.
Pain that does not respond to local anaesthetic drops suggests a more severe problem, more than just a superficial conjunctival or corneal injury.
Topical anaesthetic drops are only contraindicated in neonates, or if the patient has a known allergy to the medication.
After irrigating the eye:
- Assess for surface epithelial defects by fluorescein sodium staining with the cobalt blue light of the ophthalmoscope.
- Assess and document visual acuity.
Technique: ocular irrigation
- Gather your equipment
-A number of saline bags
-A giving set
- Sit the patient by a sink, or ask the parent to support their head by the sink
– For very young children, it may be worth wrapping them in a towel or a sheet like a burrito to keep them still
– If you have time, it can also be a good idea to remove any of the child’s clothing you don’t want to get wet!
- Make sure to explain the process the patient and/or parent, as irrigation can be unpleasant until a steady stream is achieved
- Gently tilt the head back over the sink – this is a good point to instill local anaesthetic drops if they are needed
– Don’t forget to warn about the sting!
– Don’t forget to reapply if required, the drops will also wash away with the irrigation
- In older children, always check if they’re wearing contact lenses – these should be removed if present
- Use a 500ml bag of 0.9% sodium chloride or Hartmann’s and empty it into the conjunctival sac – you can either use a purpose-built irrigator or a standard giving set. A top tip is to cut the end of the tubing to deliver fluid more quickly.
- Make sure to irrigate under the upper and lower eyelids
- Continue for at least 20-30 minutes
- As a rough guide, you can check the pH between bag change-overs, or every 5 minutes
Further management may include:
- Topical broad-spectrum antibiotics such as moxifloxacin or chloramphenicol for 5-7 days to prevent infection
- Steroid eye drops to reduce inflammation. But, these should be used with caution and only on specialist advice because of their effect on collagen synthesis and healing
- Cycloplegics such as atropine eye drops for comfort
- Lubricant eye drops to promote healing
In general, eye patching is not recommended. In severe cases, the goal is to restore clarity to the ocular surface. Extensive scarring may require surgical debridement or limbal stem cell grafting to help restore vision.
Complications and prognosis
Superficial eye injuries generally have a very good prognosis. Complications can include:
- Symblepharon – adhesions between the conjunctiva of the eyelid and the conjunctiva of the eyeball
- Secondary glaucoma – raised intraocular pressure with risk of nerve damage, leading to visual loss
- Poor corneal healing
- Pseudopterygium – adhesions between the conjunctiva and the cornea
- Corneal opacification
After a quick assessment of the presenting complaint, the triage nurse irrigates Belle’s eye with 1L of normal saline over 15 minutes. 10 minutes after finishing the irrigation, the ocular pH is 7. When the doctor sees her, Belle is able to open her eye fully and appears comfortable, with mild residual conjunctival redness. Her cornea is completely clear and there is no overt ischaemia.
Assessing visual acuity is difficult, but Belle is able to successfully reach for toys and can recognise a picture of a duck even with her left eye closed. With Dad’s help, fluorescein drops are administered (a few administrations and a piece of gauze are required, as Belle is crying orange tears at this point) and the corneal surface is assessed for epithelial defects – there are no areas of stain uptake, indicating no corneal injury.
After a full history and examination and addressing Dad’s concerns, Belle is discharged home with safety netting advice to return if any concern about her vision or worsening redness or irritation. Dad is given some general safety advice about supervision and keeping chemicals out of reach.
To think about…
How would you address Dad’s concerns that Belle will go blind in her right eye?
A sticky situation: Super-Glue®️
Super-Glue is a staple in every home. It bonds dry surfaces and in the wrong hands it can end up in the eye, bonding the lashes together. But, the stickiness doesn’t stop there – it can pool in the lower conjunctival fornix, causing conjunctivitis or a corneal abrasion.
The initial management depends on whether the eye can be opened or not.
If the eye can be opened and there is ANY evidence of discomfort or conjunctival irritation, irrigate the eye. Examine the ocular surface for glue (including under the lids) or signs of corneal abrasion – fluorescein is your friend here. It will help highlight the glue. Local anaesthetic drops such as tetracaine can be used with good effect.
Remove any visible glue using a cotton bud, if possible. If there are any concerns or difficulty in removing pieces, it may require referral for specialist examination and removal. Young children may also a need referral to enable adequate examination. If the eye is closed, moisten the glue with warm water and gently remove as much as possible. Try to separate the lids – this may require you to cut the eyelashes. If the child reports pain or looks like they’re in pain or discomfort, there may be glue on the ocular surface. This requires referral for specialist examination if you’re unable to open the eyelids and assess the ocular surface. In most cases, the lids spontaneously separate within a week.
Take home messages
The primary factors determining outcome after chemical eye injuries are duration of contact with the eye – timely and effective irrigation is so important.
When it comes to acid versus alkali, alkalis are worse, with the exception of hydrofluoric acid
Superficial eye injuries generally have a very good prognosis.
Corneal clarity can be used as a quick way to assess visual prognosis.
IRRIGATE, IRRIGATE, IRRIGATE.
Dua, H.S., King, A.J. and Joseph, A., 2001. A new classification of ocular surface burns. British Journal of Ophthalmology, 85(11), pp.1379-1383.
Haring, R.S., Sheffield, I.D., Channa, R., Canner, J.K. and Schneider, E.B., 2016. Epidemiologic trends of chemical ocular burns in the United States. JAMA ophthalmology, 134(10), pp.1119-1124.
Lowth, D., 2020. Eye Trauma | Doctor. [online] Patient.info. Available at: <https://patient.info/doctor/eye-injuries#nav-3> [Accessed 22 September 2020].
MacEwen, C.J., Baines, P.S. and Desai, P., 1999. Eye injuries in children: the current picture. British journal of ophthalmology, 83(8), pp.933-936.
Sii, F., Barry, R.J., Abbott, J., Blanch, R.J., MacEwen, C.J. and Shah, P., 2018. The UK Paediatric Ocular Trauma Study 2 (POTS2): demographics and mechanisms of injuries. Clinical Ophthalmology (Auckland, NZ), 12, p.105.