Ocular emergencies

Examining equipment

• Torch

• Magnifying loupe

• Desmarres lid retractors/lid speculum

• Sterile dressing packs

• Normal saline for irrigation

• Fluorescein strips (sterile)

• Topical anaesthetic (e.g. tetracaine 1%).

Treating

• Mydriatics (dilating): tropicamide 1%, cyclopentolate 1%

• Miotic (constricting): pilocarpine 2%

• Antibiotic ointment (e.g. chloramphenicol)

• Pressure control: acetazolamide 250 mg tablets; ampoules 500 mg (Diamox)

• Eye pads, plastic shields, skin adhesive tape

• Cotton-tipped applicators (sterile)

• 25 G, 23 G disposable hypodermic needles (foreign body removal).

Corneal abrasion

The corneal epithelium is easily dislodged by a glancing blow from fingernails, twigs, stones or a paper edge. The trauma produces an acute sensation of a foreign body, with light sensitivity and excessive tearing. Lash ingrowth ( trichiasis ) may cause small abrasions.

Stain with fluorescein and measure the size of the epithelial defect. Antibiotic ointment (chloramphenicol) is instilled and an eye pad applied if a local anaesthetic is used. The condition heals spontaneously within 24 to 48 hours. Pain is due to the epithelial defect and also to reflex ciliary spasm, which may require short-acting cycloplegics, such as cyclopentolate 1%, in addition to oral analgesia.

Recent publications have suggested that topical local anaesthetic can safely be used for short periods as analgesia. This is in contrast to a long-standing edict against such use—due to toxic effects that may delay corneal healing —and represents a divergence in practice between emergency physicians and ophthalmologists. The handful of small, controlled trials has yielded equivocal evidence on safety and efficacy. As neither patient attendance for follow-up nor discarding of excess drops can be guaranteed, ongoing caution is urged as blinding side effects have been documented from overuse of topical anaesthetic. Use is absolutely contra-indicated in pre-existing dry-eye conditions (e.g. Sjogren syndrome). If deployed, use should be strictly for no more than 24 hours and the eye must remain protectively covered throughout.

Corneal foreign body

Small ferrous particles rapidly oxidize when adherent to the corneal epithelium, producing a surrounding rust ring within hours. Remove rusted particles with adequate topical anaesthesia and a bevel-up 25-gauge needle under a slit-lamp microscope. A difficult or adherent rust ring can be loosened by applying antibiotic ointment and padding for 24 hours, after which it is easily shelled out with the edge of a similar needle. Mechanical dental burrs can be difficult to sterilize and may cause large areas of epithelial removal and delay the patient’s return to work. Wooden splinters are particularly dangerous as they may easily penetrate the eye and cause violent suppuration. In all suspected foreign body injuries, evert the upper and lower lids and examine with suitable lighting, magnification and fluorescein. The conjunctival fornices may be swept gently with a moist cotton bud under topical anaesthesia.

Technique for upper eyelid eversion : the patient must look down at all times; grasp the upper lid lashes and draw the lid down, then with a cotton bud in the other hand, depress the lid 11 mm above the central lid margin (i.e. above the tarsal plate) and counter-rotate the grasped lashes and lid around this cotton-bud fulcrum. The lashes may be held against the superior orbital margin with a finger and the cotton bud removed. When the examination is complete, release the lid and allow the patient finally to look up and the lid will revert to the normal position.