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 [Figure caption and citation for the preceding image starts]: TrichiasisPrivate collection - courtesy of Mr Hugh Harris [Citation ends].com.bmj.content.model.assessment.Caption@201075c4

  • Entropion: inward turning of the eyelid margin [Figure caption and citation for the preceding image starts]: EntropionPrivate collection - courtesy of Mr Hugh Harris [Citation ends].com.bmj.content.model.assessment.Caption@5d374a5

  • Ectropion: outward turning of the eyelid margin [Figure caption and citation for the preceding image starts]: EctropionPrivate collection - courtesy of Mr Hugh Harris [Citation ends].com.bmj.content.model.assessment.Caption@455a357a

  • Blepharitis: inflammation of the eyelid margin [Figure caption and citation for the preceding image starts]: BlepharitisPrivate collection - courtesy of Mr Hugh Harris [Citation ends].com.bmj.content.model.assessment.Caption@f0552c7

  • Dry eye: symptoms or signs consistent with a deficiency of the precorneal tear film. [Figure caption and citation for the preceding image starts]: Dry eye (stained with fluorescein)From the personal collection of Dr Jonathan Smith; used with permission [Citation ends].com.bmj.content.model.assessment.Caption@4b87fd6c

Conjunctival causes

  • Bacterial conjunctivitis: inflammation of the conjunctiva caused by bacterial infection [Figure caption and citation for the preceding image starts]: Bacterial conjunctivitisPrivate collection - courtesy of Mr Hugh Harris [Citation ends].com.bmj.content.model.assessment.Caption@69256abe

  • 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][Figure caption and citation for the preceding image starts]: Viral conjunctivitisPrivate collection - courtesy of Mr Hugh Harris [Citation ends].com.bmj.content.model.assessment.Caption@1c669bf8

  • Allergic (vernal) conjunctivitis: inflammation of the conjunctiva occurring during an allergic response [Figure caption and citation for the preceding image starts]: Allergic (vernal) keratoconjunctivitisPrivate collection - courtesy of Mr Hugh Harris [Citation ends].com.bmj.content.model.assessment.Caption@76a0f2e8

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

  • Subconjunctival haemorrhage [Figure caption and citation for the preceding image starts]: Subconjunctival haemorrhagePrivate collection - courtesy of Mr Hugh Harris [Citation ends].com.bmj.content.model.assessment.Caption@7df13122

  • Subtarsal foreign body [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].com.bmj.content.model.assessment.Caption@1a5c3938

  • Conjunctival foreign body.

Corneal causes

  • Bacterial corneal ulcer: corneal epithelial defect caused by bacterial infection [Figure caption and citation for the preceding image starts]: Corneal ulcer seen with fluorescein stainPrivate collection - courtesy of Mr Hugh Harris [Citation ends].com.bmj.content.model.assessment.Caption@63539740

  • Viral corneal ulcer: corneal epithelial defect caused by viral infection [Figure caption and citation for the preceding image starts]: Dendritic ulcer seen with fluorescein stainPrivate collection - courtesy of Mr Hugh Harris [Citation ends].com.bmj.content.model.assessment.Caption@369f2e83

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

  • Contact lens-related

  • Corneal foreign body [Figure caption and citation for the preceding image starts]: Corneal foreign bodyPrivate collection - courtesy of Mr Hugh Harris [Citation ends].com.bmj.content.model.assessment.Caption@10adbae3

  • Corneal abrasion: corneal epithelial defect usually caused by trauma. [Figure caption and citation for the preceding image starts]: Corneal abrasion seen with fluorescein stainPrivate collection - courtesy of Mr Hugh Harris [Citation ends].com.bmj.content.model.assessment.Caption@77e91893

Inflammatory causes

  • Anterior uveitis: inflammation of the anterior portion of the uveal tract [Figure caption and citation for the preceding image starts]: Anterior uveitis with posterior synechiaePrivate collection - courtesy of Mr Hugh Harris [Citation ends].com.bmj.content.model.assessment.Caption@32e9f87a

  • Scleritis: inflammation of the sclera [Figure caption and citation for the preceding image starts]: ScleritisPrivate collection - courtesy of Mr Hugh Harris [Citation ends].com.bmj.content.model.assessment.Caption@1fb05f1c

  • Episcleritis: inflammation of the episclera. [Figure caption and citation for the preceding image starts]: EpiscleritisPrivate collection - courtesy of Mr Hugh Harris [Citation ends].com.bmj.content.model.assessment.Caption@559b4a50

Traumatic causes

  • Physical [Figure caption and citation for the preceding image starts]: Penetrating corneal injury with iris prolapsePrivate collection - courtesy of Mr Hugh Harris [Citation ends].com.bmj.content.model.assessment.Caption@54a48611

  • Chemical.

Other

  • Angle-closure glaucoma: closure of the iridocorneal angle leading to an acute rise in intra-ocular pressure. [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].com.bmj.content.model.assessment.Caption@6e2c330

Most common conditions

Those commonly presenting to a primary care physician are:

  • Infective conjunctivitis[6][Figure caption and citation for the preceding image starts]: Bacterial conjunctivitisPrivate collection - courtesy of Mr Hugh Harris [Citation ends].com.bmj.content.model.assessment.Caption@472101fc

  • Allergic conjunctivitis [Figure caption and citation for the preceding image starts]: Allergic (vernal) keratoconjunctivitisPrivate collection - courtesy of Mr Hugh Harris [Citation ends].com.bmj.content.model.assessment.Caption@2d42da14

  • Dry eye and other adnexal problems.[7][8]​​​​[Figure caption and citation for the preceding image starts]: TrichiasisPrivate collection - courtesy of Mr Hugh Harris [Citation ends].com.bmj.content.model.assessment.Caption@72d0c873[Figure caption and citation for the preceding image starts]: EntropionPrivate collection - courtesy of Mr Hugh Harris [Citation ends].com.bmj.content.model.assessment.Caption@70f0192c[Figure caption and citation for the preceding image starts]: EctropionPrivate collection - courtesy of Mr Hugh Harris [Citation ends].com.bmj.content.model.assessment.Caption@12de3a3[Figure caption and citation for the preceding image starts]: BlepharitisPrivate collection - courtesy of Mr Hugh Harris [Citation ends].com.bmj.content.model.assessment.Caption@365c747c​​[Figure caption and citation for the preceding image starts]: Dry eye (stained with fluorescein)From the personal collection of Dr Jonathan Smith; used with permission [Citation ends].com.bmj.content.model.assessment.Caption@492003fd

Sight-threatening causes

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

  • Angle-closure glaucoma [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].com.bmj.content.model.assessment.Caption@75434636

  • Chemical injuries

  • Conditions affecting the cornea

  • Trauma

  • Anterior uveitis. [Figure caption and citation for the preceding image starts]: Anterior uveitis with posterior synechiaePrivate collection - courtesy of Mr Hugh Harris [Citation ends].com.bmj.content.model.assessment.Caption@6120451d

Causes of red eye that can threaten vision by leading to globe rupture or perforation include: [Figure caption and citation for the preceding image starts]: Penetrating corneal injury with iris prolapsePrivate collection - courtesy of Mr Hugh Harris [Citation ends].com.bmj.content.model.assessment.Caption@1f62d661

  • Scleritis [Figure caption and citation for the preceding image starts]: ScleritisPrivate collection - courtesy of Mr Hugh Harris [Citation ends].com.bmj.content.model.assessment.Caption@46f6187a

  • 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: [Figure caption and citation for the preceding image starts]: Anterior uveitis with posterior synechiaePrivate collection - courtesy of Mr Hugh Harris [Citation ends].com.bmj.content.model.assessment.Caption@6d768033 human leukocyte antigen-B27 histocompatibility complex-positive patients, tuberculosis, syphilis, Lyme disease, sarcoidosis, Behcet's disease, and pauciarticular juvenile chronic arthritis.

  • Scleritis: [Figure caption and citation for the preceding image starts]: ScleritisPrivate collection - courtesy of Mr Hugh Harris [Citation ends].com.bmj.content.model.assessment.Caption@562f4cf5 connective tissue disorders including rheumatoid arthritis, granulomatosis with polyangiitis (formerly known as Wegener's granulomatosis), systemic lupus erythematosus (SLE), and relapsing polychondritis.

  • Episcleritis: [Figure caption and citation for the preceding image starts]: EpiscleritisPrivate collection - courtesy of Mr Hugh Harris [Citation ends].com.bmj.content.model.assessment.Caption@395272bf connective tissue disorders including rheumatoid arthritis, granulomatosis with polyangiitis (formerly known as Wegener's granulomatosis), and SLE.

  • Angle-closure glaucoma: [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].com.bmj.content.model.assessment.Caption@2f29fc66​ hypermetropia, drugs (e.g., therapeutic mydriatics, drugs with unwanted mydriatic effects such as systemic anticholinergics and topiramate).

  • Subconjunctival haemorrhage: [Figure caption and citation for the preceding image starts]: Subconjunctival haemorrhagePrivate collection - courtesy of Mr Hugh Harris [Citation ends].com.bmj.content.model.assessment.Caption@38909c7c hypertension, systemic anticoagulation, bleeding abnormalities (leukaemia, clotting disorders), conjunctival vascular lesion, trauma (including contact lens-related injury), and diabetes.

  • Dry eye: [Figure caption and citation for the preceding image starts]: Dry eye (stained with fluorescein)From the personal collection of Dr Jonathan Smith; used with permission [Citation ends].com.bmj.content.model.assessment.Caption@170f4616 connective tissue disorders including Sjogren's syndrome, rheumatoid arthritis, and SLE.

Use of this content is subject to our disclaimer