Merck Manual

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Other Eye Symptoms


Christopher J. Brady

, MD, Wilmer Eye Institute, Retina Division, Johns Hopkins University School of Medicine

Reviewed/Revised Dec 2023

Dry eyes

Eye discharge

Discharge is often accompanied by a red eye Red Eye Red eye refers to a red appearance of the opened eye, reflecting dilation of the superficial ocular vessels. Dilation of superficial ocular vessels can result from Infection Allergy Inflammation... read more and commonly is caused by allergic Allergic Conjunctivitis Allergic conjunctivitis is an acute, intermittent, or chronic conjunctival inflammation usually caused by airborne allergens. Symptoms include itching, lacrimation, discharge, and conjunctival... read more Allergic Conjunctivitis or infectious conjunctivitis Viral Conjunctivitis Viral conjunctivitis is a highly contagious acute conjunctival infection usually caused by an adenovirus. Symptoms include irritation, photophobia, and watery discharge. Diagnosis is clinical... read more Viral Conjunctivitis , blepharitis Blepharitis Blepharitis is inflammation of the eyelid margins that may be acute or chronic. Symptoms and signs include itching and burning of the eyelid margins with redness and edema. Diagnosis is by history... read more Blepharitis , and, in infants, ophthalmia neonatorum (neonatal conjunctivitis Neonatal Conjunctivitis Neonatal conjunctivitis is watery or purulent ocular drainage due to a chemical irritant or a pathogenic organism. Prevention with antigonococcal topical treatment at birth is routine. Diagnosis... read more Neonatal Conjunctivitis ). Infectious discharge may be purulent in bacterial infection, such as staphylococcal conjunctivitis or gonorrhea Gonorrhea Gonorrhea is caused by the bacterium Neisseria gonorrhoeae. It typically infects epithelia of the urethra, cervix, rectum, pharynx, or conjunctivae, causing irritation or pain and purulent... read more Gonorrhea . Less common causes include dacryocystitis Dacryocystitis Dacryocystitis is infection of the lacrimal sac that sometimes leads to abscess formation. The usual cause is a staphyloccocal or streptococcal species, typically as a consequence of nasolacrimal... read more Dacryocystitis and canaliculitis Canaliculitis Canaliculitis is inflammation of the canaliculus. The most common cause of canaliculitis is infection with Actinomyces israelii, a gram-positive bacillus with fine branching filaments... read more .

Diagnosis is usually made clinically. Allergic conjunctivitis can often be distinguished from infectious by predominance of itching, clear discharge, and presence of other allergic symptoms (eg, runny nose, sneezing). Clinical differentiation between viral and bacterial conjunctivitis is difficult. Cultures are not usually done, but are indicated for patients with the following:


Halos around light may result from cataracts; conditions that result in corneal edema, such as acute angle-closure glaucoma Angle-Closure Glaucoma Angle-closure glaucoma is glaucoma associated with a physically obstructed anterior chamber angle, which may be chronic or, rarely, acute. Symptoms of acute angle closure are severe ocular pain... read more or disorders that cause bullous keratopathy; corneal haziness; mucus on the cornea; or medications, such as digoxin, beta-blockers, or nitroglycerin.

Blue hues

Certain conditions may cause a blue tint to the visual field (cyanopsia), such as cataract removal or use of sildenafil. Cyanopsia may occur for a few days after cataract removal or as an adverse effect of sildenafil and possibly other phosphodiesterase-5 (PDE5) inhibitors.


Scotomata are visual field deficits and are divided into

  • Negative scotomata (blind spots)

  • Positive scotomata (light spots or scintillating flashes)

Negative scotomata may not be noticed by patients unless they involve central vision and interfere significantly with visual acuity; the complaint is most often decreased visual acuity Acute Vision Loss Loss of vision is usually considered acute if it develops within a few minutes to a couple of days. It may affect one or both eyes and all or part of a visual field. Patients with small visual... read more . Negative scotomata have multiple causes that can sometimes be distinguished by the specific type of field deficit Types of Field Defects Types of Field Defects as identified by use of a tangent screen, Goldmann perimeter, or computerized automated perimetry (in which the visual field is mapped out in detail based on patient response to a series of flashing lights in different locations controlled by a standardized computer program).

Drugs Mentioned In This Article

Drug Name Select Trade
Digitek , Lanoxicaps, Lanoxin, Lanoxin Pediatric
Deponit, GONITRO , Minitran, Nitrek, Nitro Bid, Nitrodisc, Nitro-Dur, Nitrogard , Nitrol, Nitrolingual, NitroMist , Nitronal, Nitroquick, Nitrostat, Nitrotab, Nitro-Time, RECTIV, Transdermal-NTG, Tridil
LiQrev, Revatio, Viagra
NOTE: This is the Professional Version. CONSUMERS: View Consumer Version
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