Ocular trauma

Summary

Injuries to the eye can pose a serious threat to vision if not treated appropriately and in a timely manner. Ocular trauma is also an easily tested topic in the Duke-Elder exam. Here, we summarise the important classes of ocular trauma to learn about: eyelid trauma; orbital trauma; trauma to the globe; and chemical injuries.

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Eyelid trauma

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,Periocular haematoma

A periocular hematoma (a ‘black eye’), is the most common blunt injury to the eyelid or forehead. It consists of a haematoma (focal collection of blood) and/or periocular ecchymosis (diffuse bruising) and oedema.

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Periocular hematomas are generally innocuous, but the following more serious conditions must be excluded:

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• Trauma to the globe/orbit

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• Orbital roof fracture

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• Basal skull fracture

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Laceration

Any lid laceration, whatever the size, requires careful exploration of the wound and examination of the globe and adnexal structures. Where possible, any lid defect should be repaired by direct closure under tension, since this offers the best functional result and cosmetic appearance.

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Infection is a risk to be aware of, even with small lacerations, which could potentially lead to orbital cellulitis. Retained foreign bodies increase the risk of orbital cellulitis, thus, a CT scan is warranted if there is suspicion of a foreign body in the soft tissues of the lid.

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It is also important to make sure each patient is up-to-date with their tetanus immunisations.

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Orbital trauma

Orbital floor fracture

Orbital floor fractures are caused by a sudden increase in orbital pressure from an impacting object. An object greater in diameter than the orbital aperture (〜5cm) causes the eyeball to be displaced rather than absorb the impact. The floor of the orbit, along the thin bone covering the infraorbital canal, is most susceptible to fracture; the bones of the lateral wall and roof are stronger and usually able to withstand the trauma. Rarely, the medial orbital wall can also be fractured.

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• Orbital floor fractures are typically caused by a ball/fist to the eye

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• The soft tissue of the globe is pushed into the maxillary sinus

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• The inferior rectus can become entrapped —> vertical diplopia and restriction of eye elevation

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• Haemorrhage and oedema in the orbit —> tightening of the septa connecting the inferior oblique muscles and inferior rectus to the periorbita —> restricting ocular motility. As the bleeding and oedema resolve with time, movement of the globe improves.

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When an extraocular muscle is entrapped, the antagonistic movement is restricted. For example, when the inferior rectus is trapped, upgaze is restricted.

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Clinical features

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• Periorbital bruising and oedema, occasionally subcutaneous emphysema (a crackling sensation on palpation due to air under the skin)

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• Vertical diplopia and inferior rectus muscle entrapment

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• Enophthalmos (posterior displacement of the eyes – ‘sunken-in’ eyes)

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• Infraorbital nerve anaesthesia (since the fractures often involve the infraorbital canal) – anaesthesia of the lower lid, cheek, side of nose, upper lip/teeth/gums

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Investigations

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• CT with coronal sections show a classical ‘tear drop’ sign representing soft tissue prolapse in the maxillary antrum

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• Hess charts (which are used to diagnose ocular motility defects) are used for monitoring and follow-up

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Management

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• Observation + oral antibiotics

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• Surgery may be required for severe fractures with entrapment of orbital contents, significant exophthalmos (>2mm) or persistent diplopia

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Patients must be instructed NOT to blow their nose, and this could force infected sinus contents in the orbit.

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Roof fracture

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• Roof fractures are rare

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• Isolated roof fractures are most common in children. There are classically caused by falling on a sharp object, or a minor blow to the forehead, and often no treatment is required

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• Roof fractures resulting from major trauma with extensive facial damage typically affect adults

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• Signs: haematoma of the upper eyelid, periocular bruising, other features of orbital wall fracture (discussed above), pulsation of the globe in large fractures (due to transmission of CSF pressure)

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• Management: same general management as an orbital floor fracture. No surgery required for small fractures; reconstructive surgery for extensive damage. A CSF leak must be excluded, due to risk of meningitis.

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Blow-out medial wall fracture

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• Normally associated with orbital floor fractures

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• Signs: periorbital bruising, subcutaneous emphysema, impaired ocular motility (involving abduction and adduction) if the medial rectus muscle is entrapped

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• Diagnosis: CT

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• Management: surgical release of incarcerated tissue and repair of the bony defect

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Lateral wall fracture

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• Rare, because the lateral wall of the orbit is stronger than other walls

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• Fractures are usually associated with severe facial damage

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Retrobulbar (orbital) haemorrhage

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Retrobulbar (also known as orbital) haemorrhage, RBH, is a rare, rapidly progressive ophthalmic emergency that can cause irreversible blindness in severe cases.

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Blood accumulation in the orbit can lead to a sharp rise in intraorbital pressure since the bony orbit is a fixed, rigid chamber. Raised intraorbital pressure restricts blood flow and can stretch the optic nerve —> optic nerve damage. This can be thought of as an acute orbital compartment syndrome.

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RBH has several causes:

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• Trauma to the orbit

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• Iatrogenic: usually due to a peri- or retrobulbar local anaesthetic block performed for intraocular surgery

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• Bleeding from vascular anomalies

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• Spontaneous haemorrhage due to poor clotting (rare)

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Clinical features

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• Painful loss of visual acuity

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• Restricted ocular movements

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• Rigid proptosis

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• Eyelid oedema and ecchymosis

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• Haemorrhagic chemosis

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• Relative afferent pupillary defect (RAPD)

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• Raised intraocular pressure

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• Optic disc swelling

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Diagnosis

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Imaging can help with diagnosis, but this shouldn’t delay treatment.

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Management

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• Surgical management has better outcomes than medical management. It is essential to immediately decompress the orbit and relieve pressure to prevent compartment syndrome and permanent visual loss

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• 1st-line: lateral canthotomy and cantholysis (LCC). Lateral canthotomy is exposure of the lateral cantonal tendon. Cantholysis involves dis-insertion of the lateral cantonal tendon (by cutting the inferior crus of the lateral cantal tendon), which releases intraorbital pressure.

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• If LCC doesn’t work, inferior septectomy and/or surgery can be performed

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• Some use medical management as an adjunct to surgery: IV acetazolamide + IV hydrocortisone

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Trauma to the globe

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Definitions

Investigations

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Consider the following investigations in cases of globe trauma:

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• X-ray – where a foreign body is suspected

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• Ultrasound – useful to detect intraocular foreign bodies, globe rupture, retinal detachment and suprachoroidal haemorrhage

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• CT – provides a more detailed view than simple radiographs for detecting and localising intraocular foreign bodies. It is also useful to view the integrity of intracranial, intraocular and facial structures

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• MRI – better than CT for assessing injuries of the globe itself (but not for bony injury)

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• Electrodiagnostic tests – to assess the function of the optic nerve and retina

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An MRI should NEVER be performed if there is suspicion of a ferrous metallic foreign body in the eye.

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Blunt trauma

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• Common causes: sporting injuries, assault

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• Mechanism: blunt trauma to the globe —> anteroposterior compression with concurrent expansion in the equatorial plane. This is often associated with a temporary but severe increase in intraocular pressure.

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• Prognosis usually depends on the extent of retinal injury

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The table below summarises potential consequences of blunt trauma to the globe.

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Penetrating trauma

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Penetrating eye injuries are 3x more likely to occur in males than females, and are most often caused by occupational or domestic accidents, assault and sport. They can be prevented by wearing protective eyewear.

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As well as causing direct trauma to the eye, a key issue with penetrating injuries is the risk of infection that may follow. Penetrating eye injuries can cause endophthalmitis or panophthalmitis, which are often more severe than the initial injury, and can cause loss of the eye. For this reason, prophylactic antibiotics (systemic ciprofloxacin, or in cases of contaminated IOFB, intravitreal vancomycin + ceftazidime) should be considered, and tetanus status investigated (as with eyelid trauma).

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Most penetrating eye injuries need urgent surgical repair.

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Penetrating trauma cannot be excluded even if there are no entry wounds on examination

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Intraocular foreign body (IOFB)

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All patients with penetrating eye injuries should be considered for an IOFB. IOFBs can cause damage to the eye in several ways: mechanically; by having toxic effects on ocular structures; and by causing infection.

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• Copper IOFBs with a high copper content —> an aggressive endophthalmitis-like reaction, which may progress to phthisis bulbi (’end-stage eye’). An alloy with a fairly low copper content (e.g. brass/bronze) —> chalcosis. Intraocular copper deposits can lead to anterior ‘sunflower’ cataracts and Kayser-Fleischer rings (also ophthalmic signs of Wilson’s disease)

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• Iron IOFBs —> siderosis. Iron deposition in intraocular epithelium structures —> cell necrosis —> anterior capsular cataract (consisting of iron deposits on the anterior lens capsule). It also causes reddish-brown staining of the iris —> heterochromia iridis and pigmentary retinopathy —> atrophy of the retina and retinal pigment epithelium. Trabecular damage can lead to glaucoma.

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• Aluminium and zinc are mildly toxic

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• Glass, plastic, gold and silver are inert

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Investigations

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• X-ray and CT are useful to detect and localise the IOFB

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• MRI scans are contraindicated with metallic (particularly ferrous) IOFBs, as IOFBs may be magnetised

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• Topical fluorescein may help to identify an entry wound

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Management

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• Intravitreal antibiotic prophylaxis is recommended

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• Ferrous foreign bodies: a sclerotomy is created next to the foreign body, and the IOFB is removed magnetically, followed by cryotherapy to the retinal break

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• Non-magnetic foreign bodies: a pars plana vitrectomy is performed, followed by forceps removal of the IOFB (either through the pars plana or the limbus)

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Chemical injuries

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Chemical and thermal injuries can be severe, resulting in severe corneal scarring and permanent visual loss, hence timely management is critical.

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• Alkali burns are twice as common as acid burns (as they are more widely used in homes and in industry). The most commonly involved alkalis are sodium hydroxide, ammonia and lime. Sodium hydroxide and ammonia cause more severe damage due to rapid penetration.

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• Alkali injuries are more serious than acids, as they are lipophilic and hence penetrate more deeply than acids. This is because acids coagulate surface proteins, forming a protective barrier.

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• Alkalis cause damage via liquefactive necrosis

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• Acids cause damage via coagulative necrosis

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,Management

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Emergency management

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Severe burns should be admitted to hospital.

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• Copious irrigation for 15-30 minutes, ****ideally with a sterile balanced buffered solution (e.g. normal saline or Ringer lactate), but tap water may be used if necessary – this minimises duration of contact with the chemical, and helps to normalise the pH in the conjunctival sac. The speed and efficacy of irrigation is the most important prognostic factor following chemical injury. Topical anaesthetic should be given before irrigation to make the procedure more comfortable and increase cooperation.

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• Double eversion of the upper eyelid – so that any trapped particles can be identified and removed

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• Debridement of necrotic areas of corneal epithelium

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Medical management

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• Administer topical antibiotics ± topical steroids and cycloplegics. Topical antibiotics are for prophylaxis of bacterial infection; steroids reduce inflammation; and cycloplegics may improve comfort.

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• Ascorbic acid (not to be used in acid burns) – improves wound healing by promoting collagen synthesis

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• Doxycycline – a proteinase inhibitor which helps healing

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Long-term corneal healing problems

Corneal epithelium healing involves the migration of limbal stem cells. Consequently, if there is damage to the limbus, corneal healing is impaired. Possible solutions include:

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• Amniotic membrane grafting

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• Limbal stem cell transplant

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References

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1. Salmon, John F., and Jack J. Kanski. Kanski’s Clinical Ophthalmology: A Systematic Approach. Ninth Edition, Elsevier, 2020.

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2. ‘Evaluation and Management of Orbital Hemorrhage’. American Academy of Ophthalmology, 1 Jan. 2011, https://www.aao.org/eyenet/article/evaluation-management-of-orbital-hemorrhage.

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3. Loporchio, Dean, et al. ‘Intraocular Foreign Bodies: A Review’. Survey of Ophthalmology, vol. 61, no. 5, 2016, pp. 582–96. PubMed, https://doi.org/10.1016/j.survophthal.2016.03.005.

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4. Bouchaouch, A., et al. ‘Les Traumatismes de l’étage Antérieur de La Base Du Crane: À Propos d’une Série de 136 Cas’. The Pan African Medical Journal, 2015. www.semanticscholar.org

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5. Gonzalez, Mithra O., and Vikram D. Durairaj. ‘Indirect Orbital Floor Fractures: A Meta-Analysis’. Middle East African Journal of Ophthalmology, vol. 17, no. 2, 2010, pp. 138–41. PubMed Central, https://doi.org/10.4103/0974-9233.63076.

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6. MD, James Heilman. English: A Corneal Abrasion Made Apparent after Staining with Fluorescein. This Is an Edited Version of the Source Image Made for Use in the ‘Anatomist’ IOS and Android App and Shared Here under the Terms of the Source Image’s Share Alike Creative Commons License. 1 Feb. 2017.

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7. Nakatani, Yusuke, et al. ‘Successful Treatment of Corneal Wasp Sting-Induced Panuveitis with Vitrectomy’. Journal of Ophthalmic Inflammation and Infection, vol. 3, Jan. 2013, p. 18. PubMed Central, https://doi.org/10.1186/1869-5760-3-18.

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8. Mutie, Dorothy, and Nyawira Mwangi. ‘Assessing an Eye Injury Patient’. Community Eye Health, vol. 28, no. 91, 2015, pp. 46–48. PubMed Central, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4790160/.

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9. Kaur, Savleen, et al. ‘Traumatic Glaucoma in Children’. Journal of Current Glaucoma Practice, vol. 8, no. 2, 2014, pp. 58–62. PubMed Central, https://doi.org/10.5005/jp-journals-10008-1162.

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10. Zhang, Ke-Ke, et al. ‘Siderotic Cataract with No Signs of Intraocular Foreign Body’. BMC Ophthalmology, vol. 17, no. 1, Mar. 2017, p. 26. PubMed, https://doi.org/10.1186/s12886-017-0424-4.

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11. Kodama, Hiroko, et al. ‘Inherited Copper Transport Disorders: Biochemical Mechanisms, Diagnosis, and Treatment’. Current Drug Metabolism, vol. 13, no. 3, Mar. 2012, pp. 237–50. PubMed Central, https://doi.org/10.2174/138920012799320455.

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