The red eye is the most common ocular condition responsible for self- referrals to clinics through out the world. 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). This article reviews red eye conditions that threaten eye sight and even life.

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. 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.

Subconjunctival Hemorrhage
A subconjunctival hemorrhage (Fig. 1) is often the cause of acute ocular redness. The diagnosis is based on simple observation of the characteristic features of such a hemorrhage: the redness, which is unilateral, is localized and sharply circumscribed, the underlying sclera is not visible, the adjacent conjunctiva is free of inflammation, and there is no discharge. There is also no pain, and vision is unaffected. Contributory factors include trauma (which may be so minor that the patient does not recall it), fragile conjunctival vessels, bleeding disorders, anticoagulation therapy, and hypertension. A sub-conjunctival hemorrhage sometimes results from prolonged coughing, vomiting, or a vigorous Valsalva maneuver. No specific treatment is necessary, but an evaluation for contributory factors should be undertaken. The patient should be reassured that the hemorrhage will clear gradually in two to three weeks. Failure to resolve suggests a less common cause (e.g., Kaposi's sarcoma) and warrants a referral to an ophthalmologist.

Figure1: Sub-conjunctival Hemorrhage

The sharply demarcated hemorrhage prevents the visualization of underlying structures. There is no inflammation in contiguous areas. This disorder does not affect vision and almost always clears spontaneously.

Of the disorders that cause a red eye, conjunctivitis is the one that the primary care physician is most likely to encounter. Conjunctivitis is characterized by dilatation of the superficial conjunctival blood vessels, resulting in hyperemia and edema of the conjunctiva, with discharge. A purulent discharge generally suggests a bacterial infection, but otherwise, the nature of the discharge is not clinically useful in determining the cause. Fluid may accumulate beneath the loosely attached bulbar conjunctiva, causing it to balloon away from the globe (a phenomenon known as chemosis). Patients with conjunctivitis do not usually

Report visual problems or ocular discomfort

Figure 2: Red Eye Differential Diagnosis Algorithm

Conjunctivitis due to viral infection (Fig. 3), the leading cause of a red eye, is characterized by conjunctival hyperemia and edema, a watery discharge, and occasionally small hemorrhages. The disorder often affects one eye first and the other a few days later. The lids may be swollen. Conjunctivitis may develop during or after an upper respiratory tract infection or after exposure to a person with such an infection. A watery discharge may cause intermittent blurring, but vision is otherwise unaffected. Photophobia is uncommon. A palpable preauricular lymph node strongly supports the diagnosis but is not present in the majority of cases. Viral conjunctivitis is usually self-limited, but there is evidence that treatment with a topical antibiotic shortens its course.

Figure 3: Presumed Viral Conjunctivitis

In this case, no pathogen was identified by laboratory studies, but a history of a recent upper respiratory tract infection and the absence of purulent exudates supported the diagnosis. Viral conjunctivitis is usually self-limited. Broad-spectrum antibacterial eye drops (e.g., a combination of trimethoprim [1mg per milliliter] and polymyxin B [10,000 units per milliliter], one or two drops four times a day) are often prescribed. The ostensible reason for this treatment is to prevent bacterial super- infection, but the actual reason in many cases is that the patient will not accept a recommendation that no therapy be administered. Topical antiviral drugs are not administered. The patient must be informed that viral conjunctivitis is highly contagious. In cases of adenoviral conjunctivitis (Fig. 4) and presumably other forms of viral conjunctivitis, replicating virus is present in 95 percent of patients 10 days after the appearance of symptoms but in only 5 percent on the 16th day.

Figure 4: Severe Adenoviral Conjunctivitis

This case occurred during an outbreak of epidemic keratoconjunctivitis.

The disorder is highly contagious, with replicating virus present in most infected persons 10 days after the development of symptoms and signs.

The patient should be told not to share towels or other objects that might be contaminated and to avoid close contact with other persons, including indirect contact (e.g., in a swimming pool), for approximately two weeks. Similarly, the physician must be thorough with hand washing and decontamination of instruments. If there is no improvement in 7 to 10 days, the patient should be referred to an ophthalmologist

Prevalence of bacterial conjunctivitis

Although bacterial conjunctivitis can occur at any age, it frequently occurs in preschool- and school-age children. For example, it is estimated that 51% of all treatments for bacterial conjunctivitis occur in the 0- to 9-year age group (23% in infants 0 to 2 years and 28% in children 3 to 9). Another 13% of treatments are reported to occur in the patient's age 10 to 19 years.

Differential diagnosis of Bacterial Conjunctivitis

Unilateral conjunctivitis for more than a few days is unusual and should prompt a thorough assessment for the possibility of other, often more serious, eye conditions. Bacterial conjunctivitis can be diagnosed based on the following siginificant clinical characteristics

Types

1. Simple bacterial conjunctivitis

Figure 5: simple bacterial conjunctivitis

• Essence - bacterial infection may be by commensals or exogenous bacteria. Common culprits include S. aureus , S. epidermidis , S. pneumoniae and in children, H. influenzae . Bacterial conjunctivitis accounts for no more than 50% of cases of infective conjunctivitis and is more common in children than in adults.

• Risk factors - infants and children: nasolacrimal duct obstruction, concomitant otitis media or pharyngitis, exposure to affected individual. Adults: as above, lid malpositions, severe tear deficiency, immunosuppression and trauma.

• Suggestive symptoms - unilateral uncomfortable (gritty or burning) red eye with a yellow-white muco-purulent discharge. Lids often stuck shut on waking. There may be mild photophobia.

• Signs to look for - crusted lids (± edema), evidence of mucous strands / discharge, velvety appearance of conjunctiva with presence of papillae and occasionally, superficial punctate keratitis.

• Management - discontinue contact lens wear, swab if large quantity of discharge, advise careful two to three times daily lid hygiene. In adults, simple bacterial conjunctivitis is usually a self-limiting condition lasting 10-14 days: good lid hygiene is enough. However, if the decision is made to use antibiotics (see below), chloramphenicol (drug of choice) or amino-glycosides are suitable choices. Fluoroquinolones are reserved for more serious infections that need to be seen in a specialist unit.

2. Gonococcal conjunctivitis

Figure 6: Gonococcal conjunctivitis

• Essence - an infection of hyper- acute onset (12-24 hours) caused by the same N. gonorrhoeae responsible for venereal genitourinary tract infections. This organism is able to invade intact corneal epithelium (so non contact wearers are no less at risk).

• Risk factors - contact with infected individuals, presence of other sexually transmitted diseases.

• Suggestive symptoms - rapid onset of uni- / bilateral hyper- purulent red eye.

• Signs to look for - tender lid oedema, profuse discharge, keratitis (look for oedema, fluorescein uptake, decreased visual acuity and photophobia), and preauricular lymphadenopathy.

• Management - discontinue contact lens wear, swab, and refer on for further assessment. Systemic treatment will be with cefotaxime (length depends on whether there is corneal involvement or not) ± topical antibiotics.

• Additional notes - the patient should be assessed for evidence of other venereal disease and treated concurrently for Chlamydia infection. They should be informed of the nature of this infection and sexual partners should also be traced and treated as appropriate.

3. Chlamydial conjunctivitis

Figure 7: Chlamydial conjunctivitis

•  Essence - Chlamydial inclusion conjunctivitis is caused by serotypes D to K of Chlamydia trachomatis . It is transmitted by autoinoculation or eye to eye spread. It is a sexually transmitted disease with an incubation period of 1 week and may be associated with urethritis or cervicitis

•  Risk factors - contact with infected individuals, presence of other sexually transmitted diseases.

•  Suggestive symptoms - chronic low-grade conjunctivitis (may persist for 3 to 12 months if left untreated) with a green stringy discharge in the morning.

•  Signs to look for - inferior conjunctival follicles, superior corneal pannus (superficial corneal neovascular area), palpable preauricular lymph nodes.

•  Management - discontinue contact lens wear, topical treatment with tetracycline ointment (q.i.d. for 6 weeks) and systemic doxycycline (100 mg b.i.d for 1-2 weeks) or azithromycin (1 gm single dose) or erythromycin (500 mg q.i.d for 1 week if tetracycline is contraindicated). There is ongoing debate as to which antibiotic is most effective (alone or in combination) but doxycycline is a good starting drug if there are no contraindications and in small studies, has been associated with 100% cure rate. Azithromycin 1% eye drops are the latest development in the armamentarium of trachoma treatment , and are known to be significantly effective in eradicating Chlamydia trachomatis

 4. Ophthalmia Neonatorum (ND)

Figure 8: Ophthalmia Neonatorum (ND)

•  Essence - this is conjunctivitis within the first 28 days of life. It may be chemically induced or arise as a result of infection. A number of pathogens can be involved through either contamination from the maternal genital tract ( N. gonorrhoeae, C. trachomatis , Group B beta haemolytic streptococcus) or by cross infection ( S. aureus , coliforms, pseudomonas). Chlamydial infection (which presents 5-19 days after birth) is the most common cause of neonatal conjunctivitis and is a notifiable disease. It may be associated with systemic chlamydial infection, otitis, rhinitis and pneumonia. Gonococcal infection presents 1-7 days after birth.

•  Risk factors - vaginal delivery by infected mother.

•  Signs to look for - purulent / mucoid discharge from one or both eyes associated with diffuse conjunctival injection. There may be eyelid edema.

•  Management - Refer to ophthalmologists and look into treating maternal infection
(± sexual partners). These babies will receive systemic treatment (erythromycin for chlamydial infection and ceftriaxone for gonococcal infection) and will be monitored extremely closely; they are likely to be admitted for gonococcal infection in order to monitor for development of disseminated infection.

Complications

• Serious complications are rare in simple adult bacterial conjunctivitis.

• Corneal ulceration: healthy intact corneas are relatively resistant to infection. However, contact lens wearers may have compromised corneas due to hypoxia, foreign body tracts from debris trapped between lens and eye or staining from lens use. Damaged corneal epithelium provides a potential point of entry for microorganisms.

• Chronic bacterial conjunctivitis can occur with eyelid disease such as blepharitis and meibomian gland inflammation.

• Some organisms cause corneal or systemic complications, or both. Otitis media may develop in 25% of children with Haemophilus influenzae conjunctivitis, and systemic meningitis may complicate primary meningococcal conjunctivitis in 18% of cases. Pneumonia occurs in 10 -20% of infants following chlamydial conjunctivitis and neonatal conjunctivitis can result in a severe localized infection of the eye and potentially serious systemic complications.

Management

Bacterial conjunctivitis is generally considered to be self-limiting, but effective topical therapy decreases both the duration and morbidity associated with the disease. Most patients with bacterial conjunctivitis are treated empirically with topical antibiotics without previous bacteriologic identification. Therefore, it is important that initial treatment offers the greatest potential for rapid eradication of a broad range of suspected Gram-negative and Gram-positive pathogens.

Although viral infections typically do not require antibiotics, the treatment of a suspected case of viral conjunctivitis with eye drops or ointment may be started immediately to prevent an additional bacterial infection or because it might be difficult to determine whether the infection is caused by a bacterium or a virus.

The safety of a drug to treat ocular infections in children and in the overall population is of paramount importance .Patient compliance with dosing of a topical antibiotic is necessary to effectively fight bacterial ocular infections.

General approaches for using topical antibiotics

The most common topical ophthalmic agents for treatment of bacterial ocular infections include chloramphenicol, aminoglycosides, polymyxins, and fluoroquinolones.

Chloramphenicol

•  Chloramphenicol is regarded as the first-line antibiotic.

It has a relatively broad spectrum of action against most Gram-positive and Gram-negative bacteria, and there is little evidence of bacterial resistance to chloramphenicol.

•  Concern about the systemic toxicity of topical chloramphenicol, in particular aplastic anemia, is not well founded [Rayner and Buckley, 1996; Lancaster et al, 1998; Walker et al, 1998; Field et al, 1999; Robert and Adenis, 2001; BNF 47, 2004].

•  Due to the potential risk of systemic absorption

Chloramphenicol is not recommended for prolonged treatment periods or when treatment is combined with other myelotoxic drugs [Walker et al, 1998].

Can be used in children above the age of 2 years

Aminoglycosides: Tobramycin, Gentamicin, Neomycin etc

•  Aminoglycosides lack efficacy against S. Epidermidis and S. Pneumoniae

•  The incidence of resistance among gram positive bacteria is unacceptably high (29 to 41%).

•  Aminoglycosides gentamicin and tobramycin have weak activity against Staphylococcal species and some strains of pseudomonas have found to be resistant to aminoglycosides.

•  Spectrum : narrow spectrum of action , limited gram positive coverage

•  Safety : aminoglycosides cause corneal epithelial toxicity

•  Certain aminoglycosides, such as neomycin and gentamicin, may even worsen the symptoms of conjunctivitis.

•  Gentamicin has significant toxicity and may cause increased irritation in an already red eye.

•  Many patients may experience sensitivity to neomycin, including an allergic reaction.

•  Quinolones: Ciprofloxacin, ofloxacin, levofloxacin, moxifloxacin gatifloxacin

Topical ocular fluoroquinolones, such as ciprofloxacin ofloxacin, have been used to safely treat conjunctivitis, in pediatric and non-pediatric patients for many years. Unfortunately, emerging bacterial resistance raises concerns about the effectiveness of current fluoroquinolones.

To enhance compliance, the currently marketed solution of moxifloxacin ophthalmic solution 0.5% is formulated at a physiological pH of 6.8 and does not include the preservative, benzalkonium chloride, which can have toxic effects. Unlike other topical ophthalmic antibiotics, moxifloxacin has been formulated and packaged as a self preserved formulation and requires no added preservative.

•  Pediatric population

In the five clinical studies, the safety profile of a solution of moxifloxacin ophthalmic solution 0.5% was evaluated in 462 pediatric patients (3 days–17 years old) who received at least one dose of study medication. Moxifloxacin ophthalmic solution 0.5% was safe and well tolerated in pediatric patients, including all age categories: newborns (0–27 days), infants and toddlers (28 days–23 months), children (2–11 years), and adolescents (12–17 years).

•  Non pediatric population

In the five clinical studies, the safety profile of moxifloxacin ophthalmic solution 0.5% was evaluated in 531 non-pediatric (i.e., adult and elderly) patients who were 18 to 93 years old and received at least one dose of study medication. Moxifloxacin ophthalmic solution 0.5% was safe and well tolerated in adult (18- 64 years old) and elderly (65 years and older) patients. No serious adverse event assessed as related to therapy was reported in any adult or elderly patient.

Allergic conjunctivitis' is an umbrella term for a group of diseases which affect the ocular surface

Clinically, allergic conjunctivitis is inflammation of the conjunctiva due to allergy.

The eye is probably the most common site for the development of allergic inflammatory disorders, because allergens can directly impact on the eye's surface. The ocular component may be the most prominent and sometimes disabling feature of allergy.

Although many cases are seasonal, a large number of patients have year-round symptoms.

Overview of Allergic Conjunctivitis

The 2 most commonly occurring allergic conjunctivitis are seasonal allergic conjunctivitis and perennial allergic conjunctivitis.

•  Seasonal Allergic Conjunctivitis (SAC)

Seasonal allergic conjunctivitis (SAC) is the most common allergic disease affecting the eye, with an estimated prevalence of approximately 15% to 20% worldwide . SAC is the most common form of allergic conjunctivitis, representing more than 50% of all cases of allergic conjunctivitis. The onset of symptoms is seasonally related to specific circulating aeroallergens. Grass pollens have been noted to be associated with increased ocular symptoms during the spring and, in some areas, during Indian summer season.

The ocular symptoms are frequently associated with nasal or pharyngeal complaints

•  Perennial allergic conjunctivitis (PAC)

PAC is considered to be a variant of SAC that persists throughout the year, although 79% of patients who have PAC experience seasonal exacerbation. Dust mites, animal dander, and feathers are the most common airborne allergens implicated in PAC, and PAC is more likely than SAC to be associated with perennial rhinitis.

SAC and PAC are bilateral, self – limiting conjunctival inflammatory processes that occur in sensitized individual.

Ocular Allergy: Signs and Symptoms

Itching is considered the hallmark of ocular allergy. The pathognomonic symptom of ocular allergy is itching; without itching, the presenting condition should not be considered to be ocular allergy.

 

	Ocular itching
Chemosis /Redness		Eyelid swelling
Tearing		Foreign body sensation

Figure 9: Ocular Allergy, Signs and Symptoms

Treatment options for ocular allergies include non-pharmacological and palliative options, topical medications, oral medications, and immunotherapy. The choice of treatment will depend on the severity of the condition as well as medication cost and expected patient compliance.

Figure 10: Allergic Conjunctivitis Management Protocol

Blepharitis, an acute or chronic inflammation of the eyelid often associated with conjunctival inflammation, is caused by a variety of infectious agents, allergic disorders, and dermatologic diseases. When bacteria, particularly staphylococci, colonize the eyelash follicles and the meibomian glands, excess secretion of abnormal lipids occurs. Ocular irritation ensues, with sensation of the presence of a foreign body, accompanied by erythema and edema of the eyelid margins, misdirection and loss of eyelashes, conjunctival hyperemia, and instability of the preocular tear film. The resultant drying of the corneal surfaces exacerbates the conjunctival hyperemia and causes microscopic erosions of the corneal epithelium, mild visual distortion, and photophobia. Since most cases are chronic and require long-term therapy, they are best managed by an ophthalmologist. Abnormal apposition of the eyelid margins to the globe can cause a red eye. Entropion (inward rotation of the margin of the eyelid) and trichiasis (misdirection of the lashes toward the cornea) can irritate and abrade the ocular surface. Ectropion (outward rotation of the margin of the eyelid) can cause anomalous spreading of tears over the ocular surface; exposure keratopathy (excess evaporation of tears and drying of the corneal surface) may ensue if the eyelid abnormality is severe. Entropion and ectropion can usually be diagnosed by inspecting the eyelid. Since definitive treatment frequently requires surgical intervention, patients with these disorders should be referred to an ophthalmologist.

Episcleritis

The episclera lies beneath the conjunctiva and over the sclera. Episcleritis (Fig.11), which occurs much less often than conjunctivitis, is a self-limited, recurrent, presumably autoimmune inflammation of the episcleral vessels. It is characterized by the rapid onset of redness, a dull ache, and tenderness on palpation.

Vision is unaffected. Discharge, if present, is watery. There are focal areas of redness present within which white sclera may be observed between radially coursing, dilated episcleral vessels. An oral nonsteroidal anti-inflammatory drug (e.g., aspirin) may relieve the symptoms, but reassurance that the condition is

Self-limited and will clear spontaneously is often all that is required. Persistent or recurrent disease warrants a referral to an ophthalmologist.

Figure 11: Episcleritis

There are engorged, radially oriented vessels and a nodule adjacent to the limbus. In this case, the opposite (nasal) sector of the conjunctiva and episclera was not inflamed. This presumably autoimmune disorder is generally self-limited.

Scleritis
Scleritis can impair vision and may be associated with a life-threatening vascular or connective-tissue disease (e.g., rheumatoid arthritis). Fortunately, scleritis is much less common than conjunctivitis or episcleritis. The redness may be focal or diffuse, and the underlying sclera is pink. Typically, there is moderate- to-severe, deep ocular pain and tenderness on palpation. The diagnosis of scleritis calls for a prompt referral to an ophthalmologist; an oral non-steroidal anti-inflammatory drug may help relieve symptoms in the interim. Treatment often requires systemic corticosteroids, anti-metabolites, or both and should be managed concurrently by the ophthalmologist and the primary care physician.

Pterygium
A pterygium (Fig. 12) is a benign, degenerative conjunctival lesion often seen in hot, dusty climates, particularly among persons who spend large amounts of time outdoors and are exposed to ultraviolet light (e.g., fishermen and farmers). A pterygium usually develops over a period of years and is asymptomatic, but the disorder may be manifested as acute redness of the eye if the lesion becomes inflamed and irritable. The redness is confined largely to a raised, yellowish, fleshy lesion that is usually located on the nasal side of the bulbar conjunctiva. The lesion may extend into the peripheral cornea, but unless the Para-central cornea is involved, vision is unaffected. Lubrication with artificial tears often provides adequate relief. A referral to an ophthalmologist is indicated if the lesion has recently become larger or has invaded the cornea.

Figure 12:  Pterygium

Hyperemia is confined to the elevated, nasal lesion. This degenerative condition is most common in persons who spend large amounts of time outdoors and are exposed to ultraviolet light.

A narrow anterior-chamber angle may occur in persons with hyperopia farsightedness), because the globe has a shortened axial length, and in older persons, because the increasing anterior–posterior dimension of the crystalline lens may push the iris forward. Signs and symptoms of acute angle-closure glaucoma (Fig. 13) often occur in the evening, when reduced ambient illumination provokes mydriasis, causing the accordion-like folds of the peripheral iris to block the narrow angle and prevent the outflow of aqueous humor. The result is a rapid, pronounced elevation of intraocular pressure, with redness of the eye and moderate-to-severe pain. Gentle palpation through closed lids often confirms that the involved eye is much harder than the uninvolved eye. The redness is most pronounced in the area adjacent to the limbus (circumcorneal injection). The source of the pain may not be evident. There have been cases in which nausea and vomiting, associated with headache, were so severe and persistent that exploratory laparotomy was performed before the importance of the red eye was recognized. In most instances, acute angle-closure glaucoma is unilateral. The pupil of the involved eye is moderately dilated (i.e., to a diameter of 4 to 6 mm) and unreactive to light; the other pupil is normal. Corneal haziness, due to edema, causes the iris markings to appear less sharp than those of the uninvolved eye, blurs vision, and accounts for the classic symptom of seeing haloes around lights. This condition constitutes an ocular emergency. Optic-nerve atrophy and irreversible loss of vision can occur within hours after the onset of the disorder. A prompt transfer of care to an ophthalmologist is essential.

Figure 13:  Angle-Closure Glaucoma

The pupil is moderately dilated and unreactive to light. Corneal edema causes the iris markings to appear less sharp than those of the unaffected eye. Prompt, aggressive treatment of this disorder is necessary to prevent optic atrophy.

Inflammation of the iris and ciliary body, the anterior portion of the uveal tract, usually occurs in young or middle-aged persons. The hallmark of acute anterior uveitis, also called iritis or iridocyclitis (Fig.14), is the presence of inflammatory cells and proteinaceous flare in the anterior chamber of one eye. These features usually cannot be detected without a slit lamp. If the inflammation is severe, however, leukocytes in the anterior chamber settle and form a hypopyon, a white or yellowish white, flat-topped accumulation of purulent material that is generally visible without magnification. Symptoms include pain often characterized as an ache), photophobia, and blurred vision in the involved eye. Typically, hyperemia is most pronounced in the area adjacent to the limbus (circumcorneal injection). Discharge, if present, is minimal and watery. Whereas the pupil is semi dilated in angle-closure glaucoma, in anterior uveitis the pupil is constricted and is smaller than that of the unaffected eye; it may be irregular and, at best, is sluggishly reactive to light. Anterior uveitis can cause glaucoma, pupillary abnormalities, cataract formation, and macular dysfunction. Since the disorder can impair vision, an immediate referral to an ophthalmologist is warranted.

Figure 14:  Acute Anterior Uveitis

The pupil is constricted, irregular, and poorly reactive to light. Conjunctival hyperemia is most pronounced adjacent to the limbus. A hypopyon is present (arrow). This disorder can cause loss of vision and warrants immediate referral to an ophthalmologist.

Superficial Keratitis

A wide variety of factors, including dry eyes, topical medications, viral conjunctivitis, exposure to ultraviolet light, use of contact lenses, blepharitis, and eyelid abnormalities, can cause superficial keratitis. This disorder is characterized by an inflammation of the corneal epithelium and superficial stroma, with conjunctival hyperemia. Multiple punctate lesions — some consisting of non-opaque, microscopic epithelial erosions that stain strongly with fluorescein dye and others consisting of tiny gray spots — may impart a hazy appearance to the cornea, impair vision, and cause discomfort. The specific diagnosis and management of this disorder require a slit lamp and are best left to the ophthalmologist.

Life-threatening Associations

The first priority when examining the red eye patient is to rule out an associated life-threatening condition. A patient who presents with proptosis and peri-orbital soft-tissue swelling should undergo immediate neuro-imaging to rule out an orbital mass, such as a tumor or abscess. Scleritis can present with severe eye pain and an a-vascular, non-injected area on the sclera surrounded by conjunctival injection (Figure 15). The priority is to treat any underlying systemic vasculitis that can cause scleritis, such as Wegener's granulomatosis.

Figure 15: Proptosis and peri-orbital swelling

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.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).

Table1: Red eye conditions that can cause rapid blindness

Examining the Red Eye

Primary care physicians should be on the lookout for the dangerous features of a red eye during the eye examination (Table 1). 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. A nonreactive 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 extra ocular muscles should be examined to rule out any orbital disease that causes proptosis or muscle restriction resulting in double vision.

Table 2: Features of a Dangerous red eye

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 16: Cobalt Blue Filter, Red eye Examination

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. They are prone to abuse and theft by patients with chronic eye pain and should be kept locked away.

Devices that accurately measure the eye pressure (e.g., Goldman applanation tonometer, Schiotz tonometer, Tono-Pen) are difficult to use without formal ophthalmology training. Corneal injury can occur with improper use. 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 2). The eye with the acutely elevated pressure will feel firmer. This technique is highly subjective and often inaccurate, but it does offer primary care physicians a safe method for evaluating eye pressure.

Table 3. Diagnostic characteristics of selected disorders that cause a red eye

In most cases, the ophthalmologists can correctly diagnose acute redness of the eye (Table 3) and provide an appropriate treatment.

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

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