Aetiology

Aetiology

The causes of acute red eye can be considered within the following categories:[3]

Adnexal causes

  • Trichiasis: posterior misdirection of the eyelashes from the normal site of origin com.bmj.content.model.assessment.Caption@4dd6e05c[Figure caption and citation for the preceding image starts]: TrichiasisPrivate collection - courtesy of Mr Hugh Harris [Citation ends].

  • Entropion: inward turning of the eyelid margin com.bmj.content.model.assessment.Caption@7f678403[Figure caption and citation for the preceding image starts]: EntropionPrivate collection - courtesy of Mr Hugh Harris [Citation ends].

  • Ectropion: outward turning of the eyelid margin com.bmj.content.model.assessment.Caption@39075b72[Figure caption and citation for the preceding image starts]: EctropionPrivate collection - courtesy of Mr Hugh Harris [Citation ends].

  • Blepharitis: inflammation of the eyelid margin com.bmj.content.model.assessment.Caption@41cce358[Figure caption and citation for the preceding image starts]: BlepharitisPrivate collection - courtesy of Mr Hugh Harris [Citation ends].

  • Dry eye: symptoms or signs consistent with a deficiency of the precorneal tear film. com.bmj.content.model.assessment.Caption@3be22f3d[Figure caption and citation for the preceding image starts]: Dry eye (stained with rose bengal)Private collection - courtesy of Mr Hugh Harris [Citation ends].

Conjunctival causes

  • Bacterial conjunctivitis: inflammation of the conjunctiva caused by bacterial infection com.bmj.content.model.assessment.Caption@78e6f3de[Figure caption and citation for the preceding image starts]: Bacterial conjunctivitisPrivate collection - courtesy of Mr Hugh Harris [Citation ends].

  • Viral conjunctivitis: inflammation of the conjunctiva caused by viral infection. Some patients with COVID-19 may present with features typical of viral conjunctivitis.[4] Primary care physicians should maintain a high index of suspicion for this uncommon presentation[5]com.bmj.content.model.assessment.Caption@7b39eb7b[Figure caption and citation for the preceding image starts]: Viral conjunctivitisPrivate collection - courtesy of Mr Hugh Harris [Citation ends].

  • Allergic (vernal) conjunctivitis: inflammation of the conjunctiva occurring during an allergic response com.bmj.content.model.assessment.Caption@5d491167[Figure caption and citation for the preceding image starts]: Allergic (vernal) keratoconjunctivitisPrivate collection - courtesy of Mr Hugh Harris [Citation ends].

  • Neonatal conjunctivitis: inflammation of the conjunctiva within the first month of life

  • Subconjunctival haemorrhage com.bmj.content.model.assessment.Caption@77f85634[Figure caption and citation for the preceding image starts]: Subconjunctival haemorrhagePrivate collection - courtesy of Mr Hugh Harris [Citation ends].

  • Subtarsal foreign body com.bmj.content.model.assessment.Caption@38cf3316[Figure caption and citation for the preceding image starts]: Subtarsal foreign body: vertical corneal abrasions seen with fluorescein stainPrivate collection - courtesy of Mr Hugh Harris [Citation ends].

  • Conjunctival foreign body.

Corneal causes

  • Bacterial corneal ulcer: corneal epithelial defect caused by bacterial infection com.bmj.content.model.assessment.Caption@c197547[Figure caption and citation for the preceding image starts]: Corneal ulcer seen with fluorescein stainPrivate collection - courtesy of Mr Hugh Harris [Citation ends].

  • Viral corneal ulcer: corneal epithelial defect caused by viral infection com.bmj.content.model.assessment.Caption@194e9f8a[Figure caption and citation for the preceding image starts]: Dendritic ulcer seen with fluorescein stainPrivate collection - courtesy of Mr Hugh Harris [Citation ends].

  • Fungal corneal ulcer: corneal epithelial defect caused by fungal infection

  • Contact lens-related

  • Corneal foreign body com.bmj.content.model.assessment.Caption@2c323361[Figure caption and citation for the preceding image starts]: Corneal foreign bodyPrivate collection - courtesy of Mr Hugh Harris [Citation ends].

  • Corneal abrasion: corneal epithelial defect usually caused by trauma. com.bmj.content.model.assessment.Caption@6da4f272[Figure caption and citation for the preceding image starts]: Corneal abrasion seen with fluorescein stainPrivate collection - courtesy of Mr Hugh Harris [Citation ends].

Inflammatory causes

  • Anterior uveitis: inflammation of the anterior portion of the uveal tract com.bmj.content.model.assessment.Caption@2ad001cc[Figure caption and citation for the preceding image starts]: Anterior uveitis with posterior synechiaePrivate collection - courtesy of Mr Hugh Harris [Citation ends].

  • Scleritis: inflammation of the sclera com.bmj.content.model.assessment.Caption@478f69d3[Figure caption and citation for the preceding image starts]: ScleritisPrivate collection - courtesy of Mr Hugh Harris [Citation ends].

  • Episcleritis: inflammation of the episclera. com.bmj.content.model.assessment.Caption@7a1bf378[Figure caption and citation for the preceding image starts]: EpiscleritisPrivate collection - courtesy of Mr Hugh Harris [Citation ends].

Traumatic causes

  • Physical com.bmj.content.model.assessment.Caption@3066a92b[Figure caption and citation for the preceding image starts]: Penetrating corneal injury with iris prolapsePrivate collection - courtesy of Mr Hugh Harris [Citation ends].

  • Chemical.

Other

  • Angle-closure glaucoma: closure of the iridocorneal angle leading to an acute rise in intra-ocular pressure. com.bmj.content.model.assessment.Caption@1a92108a[Figure caption and citation for the preceding image starts]: Angle-closure glaucoma: central corneal oedema with an oval-shaped mid-dilated pupil.Private collection - courtesy of Mr Hugh Harris [Citation ends].

Most common conditions

Those commonly presenting to a primary care physician are:

  • Infective conjunctivitis[6]com.bmj.content.model.assessment.Caption@266f23fa[Figure caption and citation for the preceding image starts]: Bacterial conjunctivitisPrivate collection - courtesy of Mr Hugh Harris [Citation ends].

  • Allergic conjunctivitis com.bmj.content.model.assessment.Caption@34a947c[Figure caption and citation for the preceding image starts]: Allergic (vernal) keratoconjunctivitisPrivate collection - courtesy of Mr Hugh Harris [Citation ends].

  • Dry eye and other adnexal problems.[7]com.bmj.content.model.assessment.Caption@6605acf[Figure caption and citation for the preceding image starts]: Dry eye (stained with rose bengal)Private collection - courtesy of Mr Hugh Harris [Citation ends].com.bmj.content.model.assessment.Caption@cfc1cc9[Figure caption and citation for the preceding image starts]: EntropionPrivate collection - courtesy of Mr Hugh Harris [Citation ends].com.bmj.content.model.assessment.Caption@53d39e5f[Figure caption and citation for the preceding image starts]: TrichiasisPrivate collection - courtesy of Mr Hugh Harris [Citation ends].com.bmj.content.model.assessment.Caption@4ed092d[Figure caption and citation for the preceding image starts]: BlepharitisPrivate collection - courtesy of Mr Hugh Harris [Citation ends].com.bmj.content.model.assessment.Caption@df8d5d[Figure caption and citation for the preceding image starts]: EctropionPrivate collection - courtesy of Mr Hugh Harris [Citation ends].

Sight-threatening causes

Causes of red eye that can threaten vision by leading to reduced visual acuity include:

  • Angle-closure glaucoma com.bmj.content.model.assessment.Caption@6c29c3db[Figure caption and citation for the preceding image starts]: Angle-closure glaucoma: central corneal oedema with an oval-shaped mid-dilated pupil.Private collection - courtesy of Mr Hugh Harris [Citation ends].

  • Chemical injuries

  • Conditions affecting the cornea

  • Trauma

  • Anterior uveitis. com.bmj.content.model.assessment.Caption@23c79967[Figure caption and citation for the preceding image starts]: Anterior uveitis with posterior synechiaePrivate collection - courtesy of Mr Hugh Harris [Citation ends].

Causes of red eye that can threaten vision by leading to globe rupture or perforation include: com.bmj.content.model.assessment.Caption@4f8f5853[Figure caption and citation for the preceding image starts]: Penetrating corneal injury with iris prolapsePrivate collection - courtesy of Mr Hugh Harris [Citation ends].

  • Scleritis com.bmj.content.model.assessment.Caption@33c6919a[Figure caption and citation for the preceding image starts]: ScleritisPrivate collection - courtesy of Mr Hugh Harris [Citation ends].

  • Physical trauma

  • Corneal ulceration

  • High-velocity foreign bodies.

These are discussed further with initial management in Emergencies: Urgent Considerations.

Risk factors

Risk factors associated with specific causes of red eye include:

  • Anterior uveitis: com.bmj.content.model.assessment.Caption@1153bb22[Figure caption and citation for the preceding image starts]: Anterior uveitis with posterior synechiaePrivate collection - courtesy of Mr Hugh Harris [Citation ends]. human leukocyte antigen-B27 histocompatibility complex-positive patients, tuberculosis, syphilis, Lyme disease, sarcoidosis, Behcet's disease, and pauciarticular juvenile chronic arthritis.

  • Scleritis: com.bmj.content.model.assessment.Caption@e4004ce[Figure caption and citation for the preceding image starts]: ScleritisPrivate collection - courtesy of Mr Hugh Harris [Citation ends]. connective tissue disorders including rheumatoid arthritis, granulomatosis with polyangiitis (formerly known as Wegener's granulomatosis), systemic lupus erythematosus (SLE), and relapsing polychondritis.

  • Episcleritis: com.bmj.content.model.assessment.Caption@3bb89895[Figure caption and citation for the preceding image starts]: EpiscleritisPrivate collection - courtesy of Mr Hugh Harris [Citation ends]. connective tissue disorders including rheumatoid arthritis, granulomatosis with polyangiitis (formerly known as Wegener's granulomatosis), and SLE.

  • Angle-closure glaucoma: com.bmj.content.model.assessment.Caption@3cf59439[Figure caption and citation for the preceding image starts]: Angle-closure glaucoma: central corneal oedema with an oval-shaped mid-dilated pupil.Private collection - courtesy of Mr Hugh Harris [Citation ends]. hypermetropia, mydriatics, and systemic anticholinergic medications.

  • Subconjunctival haemorrhage: com.bmj.content.model.assessment.Caption@3073b22e[Figure caption and citation for the preceding image starts]: Subconjunctival haemorrhagePrivate collection - courtesy of Mr Hugh Harris [Citation ends]. hypertension, systemic anticoagulation, bleeding abnormalities (leukaemia, clotting disorders), conjunctival vascular lesion, trauma (including contact lens-related injury), and diabetes.

  • Dry eye: com.bmj.content.model.assessment.Caption@3e9ba69a[Figure caption and citation for the preceding image starts]: Dry eye (stained with rose bengal)Private collection - courtesy of Mr Hugh Harris [Citation ends]. connective tissue disorders including Sjogren's syndrome, rheumatoid arthritis, and SLE.

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