Red Eye – Basics, Clinical Manifestations, Diagnosis, Treatment
- Serious sight conditions of the eye can present with redness of the eye.
- Scleritis is inflammation of the sclera that can be limited to a thin layer of connective tissue between the conjunctiva and sclera (episcleritis), or it can refer to a deeper, more severe inflammatory process. It may occur alone or with keratitis or uveitis.
- Uveitis is inflammation involving the anterior structures of the eye and can be anterior (iritis or iridocyclitis) or posterior or involve both the anterior and posterior segments of the eye (panuveitis).
APPROACH TO THE PATIENT
- Conjunctivitis is the most common cause of a red eye. However, red eye may indicate more urgent conditions.
- Key features for the evaluation of patients with red eye include the following:
- Extent and type of redness
- Preauricular adenopathy
- Patients with conjunctivitis usually present with discharge and irritation and have normal vision, clear cornea, and normal pupil.
- Chronic, unilateral red eye can be due to meibomian gland carcinoma or Kaposi’s sarcoma of the conjunctiva.
- Patients with red eye should be evaluated by an ophthalmologist, except those with a typical case of mild conjunctivitis.
- Noninfectious causes of uveitis
- Ankylosing spondylitis
- Behçet’s disease
- Inflammatory bowel disease
- Juvenile rheumatoid arthritis
- Reiter’s syndrome
- Infectious causes of uveitis
- Lyme disease
- Onchocerciasis (infection due to Onchocerca volvulus, one of the eight filarial species that infect humans)
- Pneumocystis carinii infection
- Viral infections (due to herpes, cytomegalovirus, etc.)
- Whipple’s disease
- Scleritis is frequently associated with a connective tissue disease.
- Infectious scleritis is uncommon and may be endogenous or exogenous (due to trauma or surgery). All pathogens (includingPseudomonas aeruginosa) that involve the cornea and conjunctiva can spread to the sclera. Other possible pathogens include Nocardia spp, Aspergillus spp, Pseudallescheria boydii, and Fusarium spp.
- Three types of allergic conjunctivitis:
- Hay fever conjunctivitis has a seasonal incidence and presents with itching, redness, and edema.
- Vernal conjunctivitis is also seasonal. It affects exclusively children or adolescents. The cause is unknown, but air-borne antigens are thought to trigger symptoms. Itching, photophobia, epiphora, and mucous discharge are typical.
- Atopic conjunctivitis occurs in subjects with atopic dermatitis or asthma.
- Most cases of episcleritis are idiopathic, but some occur in the setting of an autoimmune disease.
- O. volvulus infects an estimated 18 million individuals and is the second leading cause of infectious blindness worldwide. About one million of these people are blind or have severe visual impairment.
- Onchocerciasis is more common in the equatorial region of Africa, extending from the Atlantic coast to the Red Sea. A smaller number of patients live in Central and South America and Saudi Arabia.
- Subconjunctival hemorrhage can be spontaneous or from the following:
- An underlying bleeding disorder
- Blunt trauma
- Eye rubbing
- In large series, seronegative spondyloarthropathy accounts for 28% of the patients with anterior uveitis, but spondyloarthropathy is not a common cause of posterior uveitis.
- Eye involvement occurs in approximately 25% of patients with sarcoidosis, and it can cause blindness. The usual lesions involve the uveal tract, iris, ciliary body, and choroid.
- In anterior forms of scleritis, the patient complains of severe ocular tenderness and pain. With posterior scleritis, the pain and redness may be less marked.
- In conjunctivitis, pain is minimal.
- Uveitis usually presents with photophobia and visual loss.
- Episcleritis resembles conjunctivitis but is a more localized process and discharge is absent.
- Conjunctivitis due to adenovirus infection causes a watery discharge, mild foreign-body sensation, and photophobia.
- Conjunctivitis due to bacterial infection tends to produce a more mucopurulent exudate.
- In onchocerciasis, lesions may develop in all parts of the eye. The most common early finding is conjunctivitis with photophobia. Anterior uveitis can develop in about 5% of infected persons.
- In some patients, acute angle-closure glaucoma can present with nausea, vomiting, or headache, and minimal ocular symptoms are overshadowed by these, prompting a fruitless work-up for abdominal or neurologic disease.
- Bright red is usually due to subconjunctival hemorrhage, and limited redness involving only the corneal limbus suggests iridocyclitis, keratitis, or angle closure.
- Diffuse conjunctival hyperemia is nonspecific.
- The cornea is usually clear in conjunctivitis and uveitis, but can be edematous and cloudy in acute angle-closure glaucoma.
- The pupil is usually irregular and immobile in acute angle-closure glaucoma, but is usually normal in conjunctivitis.
- Visual acuity
- Conjunctivitis: slightly reduced
- Subconjunctival hemorrhage: normal
- Uveitis: normal or slightly reduced
- Intraocular pressure
- Conjunctivitis: normal
- Subconjunctival hemorrhage: normal or mildly elevated
- Uveitis: markedly elevated
- The diagnosis of anterior uveitis requires slit-lamp examination to identify inflammatory cells floating in the aqueous humor or deposited upon the corneal endothelium (keratic precipitates).
- The diagnosis of acute angle-closure glaucoma is made by measuring the intraocular pressure during an acute attack or by performing gonioscopy to reveal the narrowed chamber angle by means of a specially mirrored contact lens.
- Posterior uveitis is diagnosed by observing inflammation of the vitreous, retina, or choroid on fundus examination.
- Symptoms caused by allergic conjunctivitis can be alleviated with cold compresses, topical vasoconstrictors, topical nonsteroidal antiinflammatory agents, antihistamines, and mast-cell stabilizers. Topical glucocorticoid solutions can provide symptomatic relief, but their long-term use has been associated with glaucoma, cataract, and secondary infection.
- Episcleritis and scleritis should be treated with nonsteroidal antiinflammatory agents. If these agents fail, topical or even systemic glucocorticoid therapy may be necessary, especially if an underlying autoimmune process is active.
- In uveitis, treatment with the judicious use of topical steroids is aimed at reducing inflammation and scarring.
- Acute angle-closure glaucoma is treated with oral or intravenous acetazolamide, topical beta blockers, and pilocarpine to induce miosis. If these measures fail, a laser can be used to create a hole in the peripheral iris to relieve pupillary block.
- Ivermectin (150 g/kg single dose, either yearly or semiannually) is the first-line agent for the treatment of onchocerciasis.
- Acute angle-closure glaucoma is a medical emergency. Also, uveitis, conjunctivitis, and other infectious and noninfectious causes of red eye may lead to vision loss if left untreated.
- In onchocerciasis, complications of the anterior uveal tract may cause secondary glaucoma.
- Individuals who wear contact lenses have an impaired ability to fight conjunctivitis and are at high risk for developing vision-threatening complications.
- All patients above age 50 should have eye examinations every 2 years to check for glaucoma. Patients over age 65 should have annual examinations. Testing can start earlier in patients with a positive history.
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