Differentials
Conjunctivitis
SIGNS / SYMPTOMS
Typically presents with a red eye and discharge but without significant pain, photophobia, or changes in vision.
No history of trauma.
INVESTIGATIONS
No definitive test but generally lacks fluorescein uptake on eye exam.
Corneal laceration with globe perforation
SIGNS / SYMPTOMS
Full thickness lacerations result in a ruptured globe that allows aqueous humor to escape the anterior chamber. The cornea may appear flattened and the pupil may become asymmetric.
INVESTIGATIONS
Fluorescein applied to a full thickness lesion changes color as it is diluted with aqueous humor and streams away from the wound.
Corneal ulceration and ulcerative keratitis
SIGNS / SYMPTOMS
Typically develop over days and have signs of corneal infiltration on exam. Corneal infiltration is a white hazy infiltrate underlying a corneal defect and spreading to adjacent stroma. A dendritic pattern may be seen with herpes infection.[Figure caption and citation for the preceding image starts]: Corneal ulcer seen with fluorescein stainCourtesy of Dr Jonathan Smith, Royal Victoria Infirmary, Newcastle upon Tyne, UK; Dr Philip Severn, Sunderland Eye Infirmary, Tyne and Wear, UK; and Dr Lucy Clarke, Royal Victoria Infirmary, Newcastle upon Tyne, UK [Citation ends].
INVESTIGATIONS
An ophthalmologist can scrape the cornea with a sterile spatula or blade and send the sample for smear, cultures, and sensitivity. Gram and Giemsa staining identifies the microorganisms.
Acute angle-closure glaucoma
SIGNS / SYMPTOMS
Abrupt onset without antecedent trauma, often with severe headache, nausea, and vomiting.
Patients typically report alterations in vision with haloes around lights. The eye may have vascular congestion, corneal edema, and a dilated, unresponsive pupil. Visual acuity is often reduced.
INVESTIGATIONS
Tonometry: confirms elevated intraocular pressure; >21 mmHg is abnormal.
Gonioscopy: trabecular meshwork is not visible, as it is obscured by the peripheral iris.
Slit lamp exam: reveals a shallow anterior chamber and a large optic cup, narrowing of the neuroretinal rim, splinter hemorrhage, and nerve fiber loss.
Anterior uveitis
SIGNS / SYMPTOMS
Similar clinical presentation but with no history of trauma. Pain is usually dull.
INVESTIGATIONS
Slit lamp exam may reveal signs of protein and WBCs in the anterior chamber (cells and flare), hypopyon or a fluid level of pus, and anterior synechia where the iris adheres to the cornea.
CBC, CRP, and erythrocyte sedimentation rate are raised as nonspecific markers of inflammation.
Serum ACE is elevated in patients with sarcoidosis. If the patient is taking ACE inhibitors, medication lowers ACE levels.
Antinuclear antibodies are positive in patients with juvenile idiopathic arthritis.
Ultraviolet keratitis
SIGNS / SYMPTOMS
Patients describe some form of excessive ultraviolet exposure such as welding, significant sun exposure (solar eclipses or snow fields), or use of suntanning beds.
Onset of symptoms is typically 6-12 hours after exposure, and the eye appears injected.
INVESTIGATIONS
Fluorescein staining reveals diffuse superficial punctate epithelial irregularities referred to as superficial punctate keratitis.
Acanthamoeba keratitis
SIGNS / SYMPTOMS
In developed countries, almost always occurs in wearers of contact lenses, though it can also be associated with polluted water or other factors. Often associated with difficulty removing a contact lens.
Causes severe pain that is often discordant with the ocular findings.
Frequently associated with a ring-shaped infiltrate surrounding a central ulcer.
INVESTIGATIONS
Definitive diagnosis is by Giemsa stain and culture of a corneal scraping, or identification of Acanthamoeba DNA with polymerase chain reaction.
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