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1. Redness

Redness may be due to hyperemia of the conjunctival, ciliary, or episcleral vessels; erythema of the eyelids; or subconjunctival hemorrhage (eFigure 7–1). The major differential diagnoses are conjunctivitis, corneal disorders, acute glaucoma, and acute uveitis (see Table 7–1).

eFigure 7–1.

Spontaneous subconjunctival hemorrhage while receiving warfarin. (From the University of California, Davis, Cornea and External Diseases. Reproduced, with permission, from Riordan-Eva P, Augsburger JJ. Vaughan & Asbury's General Ophthalmology, 19th ed. McGraw-Hill, 2018.)

Beal  C  et al. Clinical evaluation of red eyes in pediatric patients. J Pediatr Health Care. 2016 Sep–Oct;30(5):506–14.
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Dunlop  AL  et al. Approach to red eye for primary care practitioners. Prim Care. 2015 Sep;42(3):267–84.
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Frings  A  et al. Red eye: a guide for non-specialists. Dtsch Arztebl Int. 2017 Apr 28;114(17):302–12.
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Navaratna  AF  et al. More than meets the (painful red) eye. Aust Fam Physician. 2016 Jun;45(6):383–4.
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2. Ocular Discomfort

Ocular pain may be caused by trauma, infection, inflammation, or rapid or marked increase in intraocular pressure.

Foreign body sensation may be due to corneal or conjunctival foreign bodies, disturbance of the corneal epithelium, or rubbing of eyelashes against the cornea (trichiasis).

Photophobia is usually due to corneal inflammation (keratitis) or anterior uveitis (iritis). Other causes are albinism, aniridia, cone dystrophy, or fever associated with various systemic infections.

Itching is characteristically associated with allergic eye disease.

Scratching and burning from dryness of the eyes may be due to lacrimal gland hypofunction, secondary to systemic disorders (eg, Sjögren disease) or drugs (eg, atropine-like agents); ocular surface disease; or dry environment.

Watering is usually due to inadequate tear drainage through obstruction of the lacrimal drainage system or malposition of the lower lid. Reflex tearing occurs with any disturbance of the corneal epithelium. Overflow of tears onto the face is termed epiphora.

Nemet  AY. The etiology of epiphora: a multifactorial issue. Semin Ophthalmol. 2016;31(3):275–9.
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Pflipsen  M  et al. Evaluation of the painful eye. Am Fam Physician. 2016 Jun 15;93(12):991–8.
[PubMed: 27304768]

3. "Eyestrain" & Headache

Refractive error including presbyopia, inadequate illumination, and latent ocular deviation are possible causes of eyestrain. Headache is rarely due to ocular disorders but is a major symptom of giant cell arteritis, an important cause of visual loss in older individuals, and can be the presenting feature of acute angle-closure glaucoma. Ocular symptoms are a feature ...

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