PANCE Blueprint EENT (9%)

Ocular Foreign body

Patient will present with →  foreign body sensation, tearing, red and severely painful eye

Metallic foreign bodies may leave a rust ring (see media)

  • If you can't remove the foreign body easily then refer to the opthamologist

Full inspection of lids, conjunctiva and cornea – Slit lamp examination will assist in identification and removal

  • X-ray or CT of may be necessary if there is evidence of penetration of the globe

If a corneal foreign body is detected, an attempt can be made to remove it by irrigation after the instillation of topical anesthetic.

  • This is particularly helpful in the case of multiple superficial foreign bodies (eg, sand).
  • An attempt can then be made to remove the foreign body with a swab, using direct visualization

Intraocular foreign bodies require immediate surgical removal by an ophthalmologist

  • Systemic and topical antimicrobials (effective against Bacillus cereus if the injury involved contamination with soil or vegetation) are indicated

Rust ring — After removal of a foreign body containing iron there is often a residual rust ring and reactive infiltrate. Patients with rust ring should be treated as patients with corneal abrasions. The rust ring itself is not harmful and will usually resorb gradually.

Corneal metallic foreign body with a "rust ring"

Corneal metallic foreign body with a "rust ring"

Question 1
A 32 year-old carpenter complains of right eye irritation all day after driving a metal stake into the ground with his hammer. He states that "something flew into my eye." Visual acuity is 20/20. Pupils are equal, round, reactive to light and accommodation. Extraocular movements are intact. There is minimal right corneal injection. No foreign body is noted with lid eversion. Fluorescein stain reveals a tiny pinpoint uptake in the area of the corneal injection. Which of the following is the most appropriate diagnostic test at this stage?
A
MRI
Hint:
MRI should never be used when there is suspicion of an iron-containing intraocular foreign body.
B
X-ray orbits
C
Applanation tonometry
Hint:
Tonometry is used to evaluate intraocular pressure, but not the presence of intraocular foreign bodies.
D
Fluorescein angiography
Hint:
Fluorescein angiography is used to evaluate vessels of the eye, not intraocular foreign bodies.
Question 1 Explanation: 
Orbital x-rays or CT scan will be most helpful in identifying an intraocular metallic foreign body.
Question 2
An 18 year-old college student took her goggles off in the chemistry lab while she was washing her glassware from an experiment she had just completed. She thinks the beaker had contained sodium hydroxide, and it splashed into her right eye. She rinsed her eye out for about five minutes in the lab. Which of the following is the most appropriate first step?
A
Check visual acuity
Hint:
Delaying irrigation of the eye to assess vision or corneal damage is inappropriate as damage to the eye may occur during the delay.
B
Flush the eye with two liters saline
C
Check for corneal damage with fluorescein
Hint:
See A for explanation.
D
Instill a topical anesthetic to facilitate examination
Hint:
Topical anesthetic may be used to facilitate irrigation with a Morgan lens, but see A for explanation.
Question 2 Explanation: 
Any chemical injury to the eye may result in severe injury and loss of sight, and is a true emergency. The eye should be irrigated copiously with at least two liters of saline, and pH checked to determine when the chemical has been cleared.
Question 3
A 10 year-old boy was playing with sparklers (magnesium sulfate) and got some of the "sparkle" in his right eye. Which of the following is the most appropriate initial treatment?
A
irrigate the eye for at least 20 minutes
B
apply Bacitracin ointment and patch the eye
Hint:
See A for explanation.
C
remove the sparkle with a moistened cotton swab
Hint:
See A for explanation.
D
protect the eye with a metal shield and refer to an eye ophthalmologist
Hint:
See A for explanation.
Question 3 Explanation: 
The magnesium from the sparkler combines with tears, producing an alkaline injury and should be treated with prolonged irrigation. Irrigation should be the first step in management of this case.
Question 4
A blacksmith presents to your clinic after feeling like something went in his eye while he was grinding on a piece of metal. You stain the eye with Fluorescein and can visualize uptake with what appears like a deep abrasion. You are unable to visualize any foreign body with your indirect ophthalmoscope. Although he makes an attempt, he complains of some visual loss in that eye. His last Tetanus booster was 4 years ago. What is the most appropriate next step in the management of this patient?
A
Administer tetanus
Hint:
Tetanus booster is only required every 5 years.
B
Prescribe Tetracaine ophthalmic
Hint:
See D for explanation.
C
Provide reassurance only
Hint:
See D for explanation.
D
Refer to ophthalmologist
Question 4 Explanation: 
Intraoccular foreign body requires emergency treatment by an ophthalmologist. Patients giving a history of something hitting the eye, particularly while hammering on metal or using grinding equipment, must be assessed for the possibility of intraoccular foreign body especially when no corneal foreign body is seen, a corneal or scleral wound is apparent, or there is marked visual loss or media opacity.
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