ocular injury - corneal foreign bodies

what is the most common type of ocular injruy

• foreign bodies

• counts for 50% of all eye injuries

what factor can cause an injury to be penetrating

• high velocity - high speed

• even a small object can penetrate if it is moving fast

what do foreign bodies affect

• usually affect the superficial cornea

• however, can cause a deeper or penetrating injury - with scarring and potential visual impairment.

what do px with a foreign body often have a history of

Patient often gives history of foreign body entering eye wind blown particles (sand, dust, vegetation) high velocity (hammering, grinding, drilling)

what are the predisposing factors of corneal foreign bodies (3)

•Hazardous occupations (e.g. machinery, construction, agriculture)

•DIY and gardening

•Lack of suitable eye protection

describe what a sub tarsal plate FB is and its aetiology (3)

• FB trapped underneath the eyelid - under tarsal plate

• px may give a history of FB entering the eye

• wind blown from an unknown source

what are the sx of sub tarsal plate FB (4)

• Foreign Body  sensation

• acute pain

• Lacrimation

• Red Eye

what is the significance/effects of a sub tarsal plate FB (2)

• when px blinks the FB will rub against their cornea - vertical linear staining on cornea

• can cause corneal abrasion and pain and irritation

what are the sx of a corneal FB (5)

• Often unilateral.

• Irriation / Foreign Body sensation /pain. Lacrimation.

• Blurred Vision.

• Red eye.

• Photophobia

what are the clinical signs of a corneal injury (6)

• Foreign Body adherent to ocular surface

• Linear Corneal Scratches, staining with fluroscein around the foreign body - thin straight scratches on the cornea - vertical

• Corneal rust ring from ferrous foreign body - left from iron/metal

• Surrounding ring of oedema and infiltrate if long-standing

• Subconjunctival haemorrhage maybe present - blood under conjunctiva

• Red Eye.

what complications may occur if a FB is not removed (3)

depending on the material:

• Iron - may cause rust rings

• Risk of infection

• Reduced/loss of vision if on the visual axis (within the pupil area)

explain importance of history taking in identification and examination of a FB (4)

• determines how the injury was caused

• If - High velocity particles – risk of globe penetration

• Metallic (ferrous) – rust ring (haemosiderosis).

• Vegetative – risk of fungal infection (from plants/gardening)

describe the management of corneal foreign bodies (4)

• Penetration into stroma, or presence of rust ring, may result in scarring and potential visual loss - therefore refer to ophthalmologist as emergency (same day)

• Loose foreign body can be irrigated away with normal saline

• Foreign body on conjunctiva can be removed with a sterile cotton bud - assess depth of corneal foreign body (slit lamp optical section)

• Carry out Seidel test to check for corneal perforation.

describe what the Seidel test and how to carry it out (3)

• used to check for a leaking wound of the cornea or sclera, meaning there may be a full-thickness injury to the eye wall

• detects whether aqueous humour is leaking out of the eye

• using FL dye - if there is a leakage - creates a bright stream or washout effect - will not be a uniform green stain - looks like a river washing through green dye = positive Seidel sign