Is it conjunctivitis or something more serious? Use this diagnostic tree to find out what's causing that red eye.
Checklist: Examining the Red Eye
- Observe eye to determine what part(s) are affected, what appears normal/abnormal, whether eye is painful, and presence of discharge.
- Develop list of diagnostic differentials based on ocular changes and conduct diagnostic testing.
- Determine whether eye is visual.
- Assess pupil size and light reflexes.
- Perform STT for quantitative assessment of tear production.
- Perform ocular surface staining:
- Fluorescein staining to assess corneal epithelium defects, NLD patency, and tear film breakup time and stability
- Seidel’s test to identify leakage of aqueous humor through cornea
- Rose bengal staining to measure precorneal tear film quality and integrity
- Perform tonometry to estimate IOP: elevation consistent with glaucoma, decrease consistent with intraocular inflammation.
- Complete examination and systemic diagnostic testing as indicated.
Blepharospasm present?
- Yes
- Diagnostic Differentials
- Corneal ulcer
- Anterior uveitis
- Acute glaucoma
- Acute lens luxation
- No
- Diagnostic Differentials
- Chronic keratitis
- Chronic glaucoma
- Posterior segment hemorrhage/disease (in absence of anterior uveitis)
- Episcleritis
- Diagnostic Differentials
Pupil size?
- Miotic
- Diagnostic Differentials
- Anterior uveitis (alone or as reflex reaction to corneal ulcer)
- Diagnostic Differentials
- Mid-range
- Diagnostic Differentials
- KCS/conjunctivitis
- Keratitis
- Corneal ulcer without accompanying anterior uveitis
- Episcleritis
- Anterior uveitis with secondary glaucoma
- Acute congestive glaucoma
- Diagnostic Differentials
- Mydriatic
- Diagnostic Differentials
- Subacute or chronic glaucoma
- Posterior segment disease (retina, optic nerve)
- Iris atrophy
- Diagnostic Differentials
Discharge present?
- Yes
- Serous
- Diagnostic Differentials
- Acute conjunctivitis
- Corneal ulcer
- Anterior uveitis
- Acute glaucoma
- Diagnostic Differentials
- Mucoid
- Diagnostic Differentials
- KCS
- Chronic conjunctivitis
- Chronic keratitis
- Diagnostic Differentials
- Serous
- No
- Diagnostic Differentials
- Chronic glaucoma
- Posterior segment hemorrhage/disease (in absence of anterior uveitis)
- Diagnostic Differentials
Conjunctival Congestion or Episcleral Injection?
- Conjunctival vessels are movable over sclera
- Episcleral vessels are fixed and typically larger
- Conjunctival vessels will blanch more rapidly following application of a vasoconstricting agent (ie, phenylephrine, epinephrine)
What part of the eye is red?
- Anterior chamber
- Diagnostic Differentials:
- Hyphema
- Interior uveitis
- Trauma
- Retinal detachment
- Systemic hypertension
- Intraocular neoplasia (primary or metastatic)
- Bleeding disorder
- Investigation
- Ultrasonography
- Systemic workup*
- Fluorescein staining
- Pupil size
- IOP
- Diagnostic Differentials:
- Fundus (reflection)
- Diagnostic Differentials:
- Variation of normal (atapetal or hypo-pigmented)
- Posterior segment hemorrhage
- Retinal detachment
- Chorioretinitis
- Systemic hypertension
- Bleeding disorder
- Intraocular neoplasia (primary or metastatic)
- Investigation
- Ultrasonography
- Systemic workup*
- Fluorescein staining
- Pupil size
- IOP
- Diagnostic Differentials:
- Iris
- Diagnostic Differentials
- Anterior uveitis (iridal hyperemia or intrastromal homorrhage)
- Intraocular neoplasia (primary or metastatic)
- Bleeding disorder
- Investigation
- Ultrasonography
- Systemic workup*
- Fluorescein staining
- Pupil size
- IOP
- Diagnostic Differentials
- Cornea†
- Diagnostic Differentials
- Uveitis
- Glaucoma
- KCS (quantitative & qualitative)
- Keratitis
- Corneal ulcer
- Investigation
- STT
- Rose bengal staining
- Cytology
- Fluorescein staining
- Diagnostic Differentials
- Conjunctiva
- Diagnostic Differentials
- Conjunctivitis (allergic, bacterial, viral)
- KCS (quantitative & qualitative)
- Excitement
- Investigation
- STT
- Rose bengal staining
- Cytology
- Fluorescein staining
- Diagnostic Differentials
- Sclera/episclera
- Diagnostic Differentials
- Glaucoma
- Anterior uveitis
- Lens luxation
- Corneal ulcer
- Episcleritis
- Excitement (scleral injection)
- Scleral hemorrhage (trauma)
- Investigation
- Fluorescein staining
- Pupil size
- IOP
- Diagnostic Differentials
IOP = intraocular pressure, KCS = keratoconjunctivitis sicca, NLD = nasolacrimal duct, STT = Schirmer’s tear test
* Systemic workup = minimum database, systemic blood pressure, coagulation parameters, infectious disease titers, thoracic/abdominal imaging
† The cornea itself is rarely red unless vascularization is present; blood may also be present within the stroma or behind the cornea, within the anterior chamber, giving the impression of a red cornea
Related Articles:
The Red Eye
Examination of the Ocular Fundus. Part 1. Normal Appearance & Light Responses
Examination of the Ocular Fundus. Part 2: Indirect and Direct Ophthalmoscopy