Ophthalmology
Question 32 of 180
A 47 year old factory worker presents to the Emergency Department with a 2 hour history of eye pain. He was grinding metal when he felt a sudden, sharp pain to the left eye. On examination you can see a metallic appearing foreign body on the surface of the cornea. Upon fluorescein staining you can see streaming of the stain below the fragment. What is your initial management of this patient?
Answer:
Fluorescein that seems to stream (positive Seidel's test) should raise suspicion for a penetrating injury (caused by leaking aqueous humor). Refer the person immediately to the emergency eye service if a suspected penetrating eye injury has occurred or an intraocular foreign body is suspected — all high-velocity injuries (such as from drilling, lawn mowing or hammering) or injuries caused by sharp objects (such as glass, metal, knives, pencils or thorns) should be treated as penetrating injuries until proven otherwise. Advise the person not to place pressure on the eye and to limit coughing or straining to prevent extrusion of intraocular contents. Do not remove foreign bodies that are visible and protruding out of the globe.Corneal Foreign Body
Ophthalmology
Last Updated: 6th January 2023
A corneal foreign body is an object (e.g. metal, glass, dust, wood, plastic, sand) either superficially adherent to or embedded in the cornea of the eye.
Clinical features
- History of precipitating event
- Sudden onset of eye pain on blinking
- Foreign body sensation (may be described as 'gritty' or 'scratching')
- Lacrimation
- Photophobia
- Decreased or blurred vision due to epithelial disruption and stromal oedema
- Conjunctival injection
- Blepharospasm (abnormal contraction of eyelid)
Assessment
- Look for visible foreign body on ocular surface - the depth of corneal involvement and possible penetration in the anterior chamber should be determined
- Fluorescein staining and the cobalt blue filter on an ophthalmoscope or slit lamp can be used to identify corneal epithelial defects — defects will fluoresce bright green
- Vertical linear scratches on cornea suggest subtarsal foreign body due to repeated scratching with blinking
- Evert the upper eyelid to to check for subtarsal foreign bodies
- The patient is asked to look down, and the examiner firmly grasps the central lashes or lid margin between the thumb and forefinger. The eyelid is pulled down and out, away from the globe. A cotton-tipped applicator is placed at the superior margin of the tarsal plate on the top of the eyelid. Slight downward pressure is applied with upwards rotation of the lid margin. Once the eyelid is everted, the thumb can be used to hold the lashes against the superior orbital margin. To invert the tarsal plate, the lashes are released and the patient is asked to look up.
- Consider possible penetrating eye injury:
- Check pupillary shape and response using a penlight or ophthalmoscope and suspect penetrating trauma if the pupil is dilated, nonreactive or irregular or the iris is protruding
- On direct inspection with a penlight, the anterior chamber should appear grossly clear, deep, and of normal contour - a flat chamber or a hyphaema raises suspicion for a penetrating injury
- Fluorescein that seems to stream (positive Seidel's test) should raise suspicion for a penetrating injury (caused by leaking aqueous humor)
Referral
Refer the person immediately to the emergency eye service if:
- A suspected penetrating eye injury has occurred or an intraocular foreign body is suspected — all high-velocity injuries (such as from drilling, lawn mowing or hammering) or injuries caused by sharp objects (such as glass, metal, knives, pencils or thorns) should be treated as penetrating injuries until proven otherwise:
- Advise the person not to place pressure on the eye and to limit coughing or straining to prevent extrusion of intraocular contents
- Do not remove foreign bodies that are visible and protruding out of the globe
- Significant orbital or periocular trauma has occurred
- A chemical injury has occurred
- A retained foreign body that cannot be removed safely is present
- Infection or corneal ulcer is suspected
- Any of the following red flag clinical features are present:
- Severe pain
- Irregular, dilated or non-reactive pupils
- Significant reduction in visual acuity
- Hyphaema or hypopyon
- Large or deep abrasions
- Corneal opacity
Management
- Remove loose superficial foreign bodies, if the expertise and equipment are available:
- Ensure that visual acuity is checked before and after attempting foreign body removal
- Irrigate the eye with normal saline to wash out the foreign body
- If saline irrigation fails, apply a topical ocular anaesthetic (such as amethocaine), and sweep a sterile cotton-tipped applicator gently over the cornea
- If the foreign body is subtarsal, evert the eyelid to access it
- Following removal of a foreign body, the person should be advised to protect the anaesthetised eye from injury, dust and bacterial contamination
- Metallic foreign bodies may leave a rust ring which requires follow up and removal by ophthalmology within 1-2 days
- If swabbing is unsuccessful foreign body removal with other disposable instruments, such as a hypodermic needle, should only be carried out by appropriately trained and experienced clinicians
- Refer immediately to ophthalmology if there is diagnostic uncertainty or the expertise or equipment for foreign body removal is not available
- Assess for corneal injury
- Consider the need for analgesia or ocular lubricants if ongoing discomfort
- Consider prescription of topical antibiotics if there is a risk of infection
Complications
- Corneal abrasion
- Corneal ulcer/infective keratitis
- Rust rings
- Penetrating eye injury
- Vision loss
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- Biochemistry
- Blood Gases
- Haematology
| Biochemistry | Normal Value |
|---|---|
| Sodium | 135 – 145 mmol/l |
| Potassium | 3.0 – 4.5 mmol/l |
| Urea | 2.5 – 7.5 mmol/l |
| Glucose | 3.5 – 5.0 mmol/l |
| Creatinine | 35 – 135 μmol/l |
| Alanine Aminotransferase (ALT) | 5 – 35 U/l |
| Gamma-glutamyl Transferase (GGT) | < 65 U/l |
| Alkaline Phosphatase (ALP) | 30 – 135 U/l |
| Aspartate Aminotransferase (AST) | < 40 U/l |
| Total Protein | 60 – 80 g/l |
| Albumin | 35 – 50 g/l |
| Globulin | 2.4 – 3.5 g/dl |
| Amylase | < 70 U/l |
| Total Bilirubin | 3 – 17 μmol/l |
| Calcium | 2.1 – 2.5 mmol/l |
| Chloride | 95 – 105 mmol/l |
| Phosphate | 0.8 – 1.4 mmol/l |
| Haematology | Normal Value |
|---|---|
| Haemoglobin | 11.5 – 16.6 g/dl |
| White Blood Cells | 4.0 – 11.0 x 109/l |
| Platelets | 150 – 450 x 109/l |
| MCV | 80 – 96 fl |
| MCHC | 32 – 36 g/dl |
| Neutrophils | 2.0 – 7.5 x 109/l |
| Lymphocytes | 1.5 – 4.0 x 109/l |
| Monocytes | 0.3 – 1.0 x 109/l |
| Eosinophils | 0.1 – 0.5 x 109/l |
| Basophils | < 0.2 x 109/l |
| Reticulocytes | < 2% |
| Haematocrit | 0.35 – 0.49 |
| Red Cell Distribution Width | 11 – 15% |
| Blood Gases | Normal Value |
|---|---|
| pH | 7.35 – 7.45 |
| pO2 | 11 – 14 kPa |
| pCO2 | 4.5 – 6.0 kPa |
| Base Excess | -2 – +2 mmol/l |
| Bicarbonate | 24 – 30 mmol/l |
| Lactate | < 2 mmol/l |
