The Red Eye: Current Concepts for Primary Care Physicians

Resident & Staff Physician®July 2005
Volume 0
Issue 0

The red eye is the most common ocular disorder seen by primary care physicians and ophthalmologists. Often benign and self-limiting, some diseases associated with a red eye can nevertheless threaten eyesight or even life. Disorders that cause rapid blindness include infectious corneal ulcers, angle-closure glaucoma, traumatic or postoperative endophthalmitis, hyperacute gonococcal conjunctivitis, chemical injuries, and ocular trauma. The many clinical images accompanying the conditions discussed will enhance recognition of the important symptoms and signs of each disease, enabling the primary care physician to appropriately manage the patient with a red eye and refer urgent cases to an ophthalmologist.

The red eye is the most common ocular disorder seen by primary care physicians and ophthalmologists. Often benign and self-limiting, some diseases associated with a red eye can nevertheless threaten eyesight or even life. Disorders that cause rapid blindness include infectious corneal ulcers, angle-closure glaucoma, traumatic or postoperative endophthalmitis, hyperacute gonococcal conjunctivitis, chemical injuries, and ocular trauma. The many clinical images accompanying the conditions discussed will enhance recognition of the important symptoms and signs of each disease, enabling the primary care physician to appropriately manage the patient with a red eye and refer urgent cases to an ophthalmologist.

Tommy S. Korn, MD, FACSAttending Ophthalmologist and Surgeon

Department of Ophthalmology

Assistant Clinical Professor of Ophthalmology

San Diego, Calif


  • Suspect child abuse in a child with a red eye caused by trauma.
  • Patients with allergic conjunctivitis will always complain of bilateral itching/tearing.
  • Avoid prescribing aminoglycoside, corticosteroid, anesthetic, or vasoconstrictor eye drops in the primary care setting.

The red eye is the most common ocular condition responsible for self-referrals to adult and pediatric primary care clinics throughout the world.1 The term "red eye" is a misused, descriptive term and not a medical diagnosis. Most physicians typically think of the red eye as a large category of diseases that present with conjunctival vascular injection (conjunctivitis). The red eye results in considerable loss of time and money because of absences from work or school. Primary care physicians, who are usually the first to encounter these patients, feel uneasy in managing eye diseases since they lack formal ophthalmology training. The purpose of this article is to review red eye conditions that threaten eyesight and even life, to enhance patient outcomes and encourage timely referrals to an ophthalmologist when appropriate.

Life-threatening Associations

The first priority when examining the red eye patient is to rule out an associated life-threatening condition. Apatient who presents with proptosis and periorbital soft-tissue swelling should undergo immediate neuroimaging to rule out an orbital mass, such as a tumor or abscess. Scleritis can present with severe eye pain and an avascular, noninjected area on the sclera surrounded by conjunctival injection (Figure 1). The priority is to treat any underlying systemic vasculitis that can cause scleritis, such as Wegener's granulomatosis.

The red eye can be associated with life-threatening conditions in children. In neonatal conjunctivitis, obtain cultures to rule out chlamydial conjunctivitis, which can be associated with life-threatening pneumonitis.2 A child with a red eye caused by ocular trauma should arouse suspicion of child abuse. Once life-threatening conditions have been excluded, the next priority is to address diseases that can lead to rapid vision loss if not diagnosed and treated properly (Table 1).

The History and Vision-threatening Conditions

Acute or chronic red eye

When taking the history, it is important to determine the duration of the red eye. If the red eye persists more than 3 weeks, suspect a chronic, benign condition, such as allergic conjunctivitis or blepharitis (inflammation of the eyelid glands). However, a chronic red eye may also represent an acute condition, such as uveitis, that has been masked by inappropriate treatment. For example, a recurrent, unilateral red eye caused by blepharitis is suggestive of sebaceous gland carcinoma of the eyelid.3 Acute red eye presentations can be more worrisome if they are associated with certain risk factors and symptoms.

Eye trauma

The physician should first determine if the acute red eye was caused by blunt or penetrating trauma. The priority is to rule out a perforating eye injury, which could lead to blindness. Signs of a ruptured globe include severe pain, diminished visual acuity, irregular pupil, deformed globe, severe eyelid swelling, severe conjunctival chemosis, hyphema (blood in the anterior chamber), absent red reflex of the pupil, proptosis, and a deep eyelid laceration.4 Aprotective shield should be placed to prevent any pressure on the eye. The patient should receive appropriate pain and antiemetic medications to prevent Valsalva pressure from extruding the contents of the eye, and be referred to an ophthalmologist for follow-up.

For chemical eye injuries, treatment should be initiated at once, even before obtaining the full history. Copious saline irrigation of the eyes will decrease the risk of irreversible corneal scarring and damage.

Previous intraocular surgery

If there is no ocular trauma, inquire about a history of cataract, glaucoma, or corneal transplant surgeries. A red and painful eye in this setting suggests the intraocular microbial infection endophthalmitis. The appearance of a milky-white layer in the anterior chamber (space between the cornea and the iris) is called a hypopyon, which consists of many packed inflammatory white blood cells (Figure 2). Endophthalmitis can occur days, weeks, months, or even years after the intraocular surgery. This diagnosis constitutes an ophthalmic emergency. Treatment includes intraocular injection of broad-spectrum antibiotics or surgery.5

Soft contact lens use

Pseudomonas aeruginosa

It is also important to ask about the use of soft contact lenses. A soft contact lens wearer with a red eye should be presumed to have an infectious corneal ulcer (bacterial keratitis) until proven otherwise. There is a high incidence of gram-negative corneal ulcers (ie, infection) in patients who sleep while wearing their contact lenses.6 Any corneal epithelial defect with an underlying "white" corneal opacity noted on examination should be assumed to be a corneal ulcer (Figure 3). Such a patient should urgently be referred to an ophthalmologist. If not properly diagnosed and treated, the risk of developing a visually debilitating scar or a corneal perforation is high because the microbial enzymes can rapidly melt the cornea.7 Treatment consists of topical fortified broad-spectrum antibiotics applied to the eye at hourly intervals. Topical corticosteroids are contraindicated in the presence of infectious corneal ulcers because they may accelerate further melting of the cornea.

Sexually transmitted infection exposure

Neisseria gonorrhoeae


Finally, inquire about the history of sexually transmitted infection exposure. The appearance of a hyperacute purulent discharge (<24-48 hours) in a sexually active patient constitutes a presumptive diagnosis of gonococcal conjunctivitis (Figure 4). can rapidly penetrate and infect an intact corneal surface, causing perforation if left untreated.8 A Gram's stain of the discharge should be obtained immediately to look for gram-negative intracellular diplococci. Gonococcal conjunctivitis requires the use of both intravenous and topical antibiotics. Such a patient should also be prescribed systemic antibiotic treatment for because of the high rate of coinfection with gonorrhea exposure.

Common Symptoms

Many symptoms are associated with the red eye. Itching usually suggests a diagnosis of allergic conjunctivitis. Patients frequently rub their eyes during peak periods of seasonal allergies. Tearing and complaints of foreign body sensation are nonspecific symptoms that do not help determine the etiology. In contrast, symptoms of blurred vision or vision loss demand a thorough investigation of the cause.

Symptoms of eye pain or photophobia suggest scleral, corneal, or intraocular inflammation. Suspect anterior uveitis in a chronic red eye with photophobia, pain, and no improvement with topical antibiotics. Uveitis refers to inflammation of the iris, ciliary body, and choroid. The eye is sensitive to light because constriction and dilation of the pupil cause pain. The diagnosis of uveitis is made with a slit lamp by visualizing inflammatory cells circulating in the anterior chamber. A patient with uveitis should be promptly referred to an ophthalmologist for topical corticosteroid therapy.

A patient with nausea and vomiting associated with unilateral eye pain and blurred vision should be presumed to have angle-closure glaucoma.9 This condition is an ophthalmic emergency because the optic nerve is at risk for damage from prolonged elevated eye pressure. Signs of angle-closure glaucoma include red eye, fixed and nonreactive pupil, and cloudy cornea. The key feature is elevated intraocular pressure. Initial treatment consists of topical and/or systemic glaucoma medications to lower the pressure. Once the pressure is medically controlled, a laser is used to create a new passageway through the peripheral iris to allow the aqueous fluid to flow freely. The peripheral iris of the other eye should also receive laser treatment as a preventive measure.

Examining the Red Eye

Primary care physicians should be on the lookout for the dangerous features of a red eye during the eye examination4 (Table 2). Before examining the eye with a bright light, visual acuity should be checked in each eye with the best distance glasses worn to correct any refractive error. Any unexplained decreased vision or asymmetric acuity between the 2 eyes requires a comprehensive workup to determine the cause. The pupils should then be examined for reactivity, symmetry, and size. Anonreactive pupil in a red eye suggests angle-closure glaucoma. Anterior uveitis can cause an irregular pupil, because the inflammatory cells circulating in the anterior chamber cause adhesions between the iris and the lens. The motility of the extraocular muscles should be examined to rule out any orbital disease that causes proptosis or muscle restriction resulting in double vision.

A magnifying glass and penlight can aid the eye examination. To properly examine the structures of the eye, such as the cornea and anterior chamber, the physician should use a slit lamp. The cornea is normally transparent; without a slit lamp, opacities or small foreign bodies can easily be missed. Any blood or inflammatory cells in the anterior chamber can only be detected by a slit lamp. The anterior chamber is normally clear; the presence of any cells or debris constitutes an ophthalmic emergency. Fluorescein dye or paper strips help stain the cornea to detect epithelial defects and perforations under cobalt blue light or a Wood's lamp (Figure 5).

A topical anesthetic drop is only used as a diagnostic aid to help facilitate the examination of patients with severe eye pain. Repeated use of topical anesthetics is toxic to the cornea; these agents should not be dispensed for corneal pain management.10 They are prone to abuse and theft by patients with chronic eye pain and should be kept locked away.11

Devices that accurately measure the eye pressure (eg, Goldmann applanation tonometer, Schi?tz tonometer, Tono-Pen) are difficult to use without formal ophthalmology training. Corneal injury can occur with improper use.12 One method of detecting asymmetrical eye pressure caused by a unilateral attack of angle-closure glaucoma is to palpate each eye with the eyelids closed (Figure 6). The eye with the acutely elevated pressure will feel firmer. This technique is highly subjective and often inaccurate,12 but it does offer primary care physicians a safe method for evaluating eye pressure.

Conditions Safe to Treat in Primary Care

Seasonal allergic conjunctivitis

A patient with allergic conjunctivitis will always complain of itching and tearing in both eyes. The eye examination reveals bilateral injection and "boggy" conjunctiva. Allergic conjunctivitis can be safely treated with artificial tears, topical antihistamine/mast cell stabilizer combination drops, and avoidance of offending allergens. Children can develop a severe type called vernal conjunctivitis that could lead to corneal scarring if not treated aggressively with topical antihistamine/ mast cell stabilizer drops. Topical corticosteroids are often used to treat severe cases of vernal conjunctivitis. As a general rule, topical corticosteroids should only be dispensed by ophthalmologists, because they can cause cataracts and glaucoma and can exacerbate viral infections, in particular ocular herpes simplex (Figure 7). Patients require constant monitoring of their eye pressure and lenses while using topical corticosteroid eye drops.

Peripheral corneal foreign bodies

Minor corneal trauma can be managed in the primary care setting if a perforating eye injury has been ruled out. If the physician possesses good manual dexterity, small foreign bodies embedded superficially in the corneal periphery can be safely removed using a slit lamp (Figure 8). Foreign bodies embedded deeply in the cornea or in the central visual axis should be removed by an ophthalmologist.

Corneal abrasions

The management of corneal abrasions involves pain relief and prevention of secondary infection. The decision to patch an eye after a corneal abrasion is very controversial.13 Patching the eye closed will alleviate some pain, but it does not accelerate corneal healing.14 Eye patching should be avoided if the corneal abrasion was caused by organic trauma or contact lenses because the patching can allow microbial contaminants to proliferate overnight on an injured surface, resulting in infectious keratitis (corneal ulcers).15 Instead, topical nonsteroidal antiinflammatory drugs have gained popularity among ophthalmologists for corneal abrasions. They offer adequate pain relief without the need to pressurepatch the eye.16,17 Table 3 lists drugs that are safe and unsafe to prescribe in the primary care setting.

Bacterial conjunctivitis

Topical antibiotics are used to prevent secondary infection after corneal abrasions and to treat bacterial conjunctivitis. Topical aminoglycosides and sulfonamides are considered outdated because of their ocular corneal toxicity (Figure 9),18 idiosyncratic reactions (Stevens-Johnson syndrome),19 and narrow spectrum of coverage. Topical fluoroquinolones have become the standard of care for treating bacterial conjunctivitis, corneal abrasions, and even some peripheral corneal ulcers.20 Topical fourth-generation fluoroquinolones (eg, moxifloxacin [Vigamox], gatifloxacin [Zymar]) have gained popularity because of their improved broad-spectrum coverage and concerns about increased antibiotic resistance.21,22 In the primary care setting, most red eye cases are caused by bacterial conjunctivitis. These potent antibiotics are useful in this setting because of their broad-spectrum coverage and lack of toxicity. The red eye patient who does not improve after 3 days of topical fourth-generation fluoroquinolone therapy should be referred to an ophthalmologist to rule out a more serious condition.

Viral conjunctivitis (pink eye)

Primary care physicians should recognize the signs and symptoms of viral conjunctivitis (ie, adenovirus infection) because of its contagious nature. Patients typically present with abrupt unilateral or bilateral symptoms consisting of watery tearing, conjunctival injection, and lid swelling. The preauricular lymph nodes are often enlarged. The patient may have developed a recent upper-respiratory tract infection or had direct contact with an infected person. There is no effective treatment for viral conjunctivitis other than supportive care (ie, artificial tears, cold compresses).23 Health care personnel should isolate these patients, wear gloves, and wash their hands to prevent an outbreak. Patients should have separate bed sheets and towels and avoid direct contact with family members, classmates, or coworkers for at least 7 days. An ophthalmology consultation is required if there is worsening of symptoms, vision loss, or corneal involvement (keratitis).

Masquerading Syndromes

Certain diseases and conditions can masquerade as a red eye. A subconjunctival hemorrhage, often caused by Valsalva pressure, is a benign, noninflammatory condition that can alarm patients (Figure 10). The appearance of salmon-colored conjunctival chemosis should raise concern for localized or systemic lymphoma (Figure 11). A red, gelatinous growth on the conjunctiva resembling a benign pterygium (a wing-shaped conjunctival extension growing over the cornea) could be a sign of squamous cell carcinoma, a more ominous condition24 (Figure 12). Physicians should be concerned when these types of conditions do not respond to conventional therapy. A conjunctival biopsy should be performed to rule out neoplasm.25


With an increased awareness, primary care physicians can appropriately manage many red eye disorders. Recognition of the key symptoms and signs of a dangerous red eye will result in timely referrals to ophthalmologists. Knowing which agents to avoid and using safer and more effective ophthalmic medications will also improve clinical outcomes.


1. Which of these is most likely to be associated with bacterial keratitis (corneal ulcers)?

  • Exposure to sexually transmitted infections
  • Previous cataract surgery

2. All the following conditions associated with red eye can lead to rapid blindness, except:

  • Traumatic endophthalmitis
  • Anterior uveitis

3. Which of these findings is most suggestive of postoperative endophthalmitis?

  • Hyphema
  • Nonreactive pupil

4. Primary care physicians can safely treat all the following conditions, except:

  • Superficial peripheral corneal foreign bodies
  • Bacterial conjunctivitis

5. Which of these medications can primary care physicians safely prescribe?

  • Tobramycin eye drops
  • Naphazoline eye drops

(Answers at end of reference list)

Preferred Practice Patterns: Conjunctivitis.

1. American Academy of Ophthalmology Cornea/External Disease Panel. San Francisco, Calif: American Academy of Ophthalmology; 2003:1-24.

Chlamydia trachomatis

Chlamydia pneumoniae

Pediatr Rev

2. Hammerschlag MR. and infections in children and adolescents. . 2004;25:43-51.

Surv Ophthalmol.

3. Kass LG, Hornblass A. Sebaceous carcinoma of the ocular adnexa. 1989;33:477-490.

The Physician's Guide to Eye Care

4. Trobe JD. . 2nd ed. San Francisco, Calif: American Academy of Ophthalmology, 2001.

Arch Ophthalmol

5. Endophthalmitis Vitrectomy Study Group. Results of the Endophthalmitis Vitrectomy Study. A randomized trial of immediate vitrectomy and of intravenous antibiotics for the treatment of postoperative bacterial endophthalmitis. . 1995;113:1479-1496.

N Engl J Med

6. Schein OD, Glynn RJ, Poggio EC, et al, for the Microbial Keratitis Study Group. The relative risk of ulcerative keratitis among users of daily-wear and extended-wear soft contact lenses. A case-control study. . 1989;321:773-778.


Clin North Am

7. Ma JJ, Dohlman CH. Mechanisms of corneal ulceration. . 2002;15:27-33.

Surv Ophthalmol.

8. Ullman S, Roussel TJ, Forster RK. Gonococcal keratoconjunctivitis. 1987;32:199-208.

N Engl J Med

9. Leibowitz HM. The red eye. . 2000;343:345-351.

J Cataract

Refract Surg

10. Sugar A. Topical anesthetic abuse after radial keratotomy. . 1998;24:1535-1537.

J Ophthalmic Nurs Technol

11. Rapuano CJ. Topical anesthetic abuse: a case report of bilateral corneal ring infiltrates. . 1990;9:94-95.


12. Ottar WL. Tonometry. 1998;23:11-17.


13. Kaiser PK, for the Corneal Abrasion Patching Study Group. A comparison of pressure patching versus no patching for corneal abrasions due to trauma or foreign body removal. . 1995;102:1936-1942.

Ann Emerg


14. Le Sage N, Verreault R, Rochette L. Efficacy of eye patching for traumatic corneal abrasions: a controlled clinical trial. 2001;38:129-134.

Am J Emerg Med

15. Schein OD. Contact lens abrasions and the nonophthalmologist. . 1993;11:606-608.


16. Kaiser PK, Pineda R II, for the Corneal Abrasion Patching Study Group. A study of topical nonsteroidal anti-inflammatory drops and no pressure patching in the treatment of corneal abrasions. 1997;104:1353-1359.

Ann Emerg Med

17.Weaver CS, Terrell KM. Evidence-based emergency medicine. Update: do ophthalmic nonsteroidal anti-inflammatory drugs reduce the pain associated with simple corneal abrasion without delayed healing? . 2003;41:134-140.

Ophthalmol Clin North Am.

18. Thomas T, Galiani D, Brod RD. Gentamicin and other antibiotic toxicity. 2001;14:611-624.

N Engl J


19. Roujeau JC, Kelly JP, Naldi L, et al. Medication use and the risk of Stevens-Johnson syndrome or toxic epidermal necrolysis. 1995;333:1600-1607.


20. Baum J, Barza M. The evolution of antibiotic therapy for bacterial conjunctivitis and keratitis: 1970-2000. . 2000;19:659-672.

Am J Ophthalmol

21. Mino de Kaspar H, Koss MJ, He L, et al. Antibiotic susceptibility of preoperative normal conjunctival bacteria. . 2005;139:730-733.

Curr Opin Ophthalmol.

22. Mah FS. Fourth-generation fluoroquinolones: new topical agents in the war on ocular bacterial infections. 2004;15:316-320.


23. Shiuey Y, Ambati BK, Adamis AP. A randomized, double-masked trial of topical ketorolac versus artificial tears for treatment of viral conjunctivitis. 2000;107:1512-1517.

Resid Staff Physician.

24. Korn BS, Korn TS. Ophthalmology photo quiz: conjunctival intraepithelial neoplasia. 2003;49(10):40, 42.


25. Akpek EK, Polcharoen W, Chan R, et al. Ocular surface neoplasia masquerading as chronic blepharoconjunctivitis. . 1999;18:282-288.


1. C; 2. D; 3. A; 4. A; 5. A

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