Assessment of red eye

Aetiology

The causes of acute red eye can be considered within the following categories:[3]Kunimoto DY, Kanithar KD, Makar M. Differential diagnosis of ocular symptoms. In: Kunimoto DY, Kanithar KD, Makar M, eds. The Wills eye manual, office and emergency room diagnosis and treatment of eye disease. Philadelphia (PA): Lippincott Williams and Wilkins; 2004:1-5.

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].

• 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].

• 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].

• Blepharitis: inflammation of the eyelid margin [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. [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 [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]Aggarwal K, Agarwal A, Jaiswal N, et al. Ocular surface manifestations of coronavirus disease 2019 (COVID-19): A systematic review and meta-analysis. PLoS One. 2020;15(11):e0241661. https://www.doi.org/10.1371/journal.pone.0241661 http://www.ncbi.nlm.nih.gov/pubmed/33151999?tool=bestpractice.com Primary care physicians should maintain a high index of suspicion for this uncommon presentation[5]Khan J, Mack HG. Management of conjunctivitis and other causes of red eye during the COVID-19 pandemic. Aust J Gen Pract. 2020 Oct;49(10):656-61. https://www.doi.org/10.31128/AJGP-04-20-5356 http://www.ncbi.nlm.nih.gov/pubmed/33015681?tool=bestpractice.com [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 [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 [Figure caption and citation for the preceding image starts]: Subconjunctival haemorrhagePrivate collection - courtesy of Mr Hugh Harris [Citation ends].

• 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].

• 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].

• 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].

• 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].

• 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].

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].

• Scleritis: inflammation of the sclera [Figure caption and citation for the preceding image starts]: ScleritisPrivate collection - courtesy of Mr Hugh Harris [Citation ends].

• Episcleritis: inflammation of the episclera. [Figure caption and citation for the preceding image starts]: EpiscleritisPrivate collection - courtesy of Mr Hugh Harris [Citation ends].

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].

• 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].

Most common conditions

Those commonly presenting to a primary care physician are:

• Infective conjunctivitis[6]Azari AA, Barney NP. Conjunctivitis: a systematic review of diagnosis and treatment. JAMA. 2013 Oct 23;310(16):1721-9. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4049531 http://www.ncbi.nlm.nih.gov/pubmed/24150468?tool=bestpractice.com [Figure caption and citation for the preceding image starts]: Bacterial conjunctivitisPrivate collection - courtesy of Mr Hugh Harris [Citation ends].

• Allergic conjunctivitis [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]Sheldrick JH, Wilson AD, Vernon SA, et al. Management of ophthalmic disease in general practice. Br J Gen Pract. 1993 Nov;43(376):459-62. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1372484/pdf/brjgenprac00038-0023.pdf http://www.ncbi.nlm.nih.gov/pubmed/8292417?tool=bestpractice.com [Figure caption and citation for the preceding image starts]: Dry eye (stained with rose bengal)Private collection - courtesy of Mr Hugh Harris [Citation ends].[Figure caption and citation for the preceding image starts]: EntropionPrivate collection - courtesy of Mr Hugh Harris [Citation ends].[Figure caption and citation for the preceding image starts]: TrichiasisPrivate collection - courtesy of Mr Hugh Harris [Citation ends].[Figure caption and citation for the preceding image starts]: BlepharitisPrivate collection - courtesy of Mr Hugh Harris [Citation ends].[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 [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. [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: [Figure caption and citation for the preceding image starts]: Penetrating corneal injury with iris prolapsePrivate collection - courtesy of Mr Hugh Harris [Citation ends].

• Scleritis [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: [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: [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: [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: [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: [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: [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.