Diseases of the Conjunctiva and Differential Diagnosis of Red Eye

Infective conjunctivitis can have bacterial or viral causes. Bacterial conjunctivitis is often self-limiting and typically results from direct eye contact with infected secretions. Common bacterial culprits include:

• S. pneumoniae
• S. aureus
• H. influenzae
• Moraxella catarrhalis

In severe cases, sexually transmitted organisms like Neisseria gonorrhoeae can be responsible. Adult chlamydial (inclusion) conjunctivitis, on the other hand, is typically caused by serological variants D-K of C. trachomatis.

Symptoms of Infective Conjunctivitis:

• Redness
• Grittiness
• Burning sensation
• Discharge
• Eyelids may be stuck together upon waking

The discharge in viral conjunctivitis is typically watery. Infective conjunctivitis is usually bilateral, although one eye may become affected 1–2 days before the other. In severe cases associated with organisms like gonococcus, meningococcus, Chlamydia, and H. influenzae, systemic symptoms may occur.

If untreated, C. trachomatis conjunctivitis can become chronic, persisting for several months. It's crucial to inquire about sexual exposure. Signs of infective conjunctivitis may vary depending on the severity of the infection, including conjunctival injection/hyperemia, mucopurulent discharge (which may start as watery), eyelid swelling and redness, especially in gonococcal infections. Hyperacute purulent discharge may indicate gonococcal or meningococcal conjunctivitis.

Investigations:

Investigations for infective conjunctivitis are not routinely performed unless indicated. In severe cases, consider:

1. Binocular conjunctival swabs and scrapings for urgent Gram staining and culture.
2. Polymerase chain reaction (PCR) in cases not responding to treatment.

Treatment:

• Approximately 60% of cases resolve within 5 days without treatment.
• Topical antibiotics (administered four times daily for up to 1 week) are typically used. Antibiotic options include:

• Chloramphenicol
• Gentamicin
• Quinolones (e.g., ciprofloxacin, ofloxacin, moxifloxacin)

For gonococcal and meningococcal conjunctivitis, use quinolones, gentamicin, chloramphenicol, or bacitracin 1–2 hourly in addition to systemic therapy.

Other treatment considerations include:

• Irrigation to remove excessive discharge.
• Reducing transmission by practicing good hand-washing hygiene.
• Avoiding the sharing of towels.
• Abstaining from sexual contact until completion of treatment (for chlamydial conjunctivitis).

Additional Information:

Viral conjunctivitis is most frequently caused by an adenovirus. Infection can be sporadic or occur in epidemics. Transmission typically happens through contact with respiratory or ocular secretions, including via fomites like contaminated towels.

Neonatal conjunctivitis, also known as ophthalmia neonatorum, refers to conjunctival inflammation that develops within the first month of life. This condition is typically transmitted from the mother to the infant during delivery.

Aetiology:

The causative organisms for neonatal conjunctivitis include:

• C. trachomatis
• N. gonorrhoeae
• Herpes simplex virus (typically HSV-2)
• Other organisms such as Staphylococci, Streptococci, Haemophilus influenzae, and various Gram-negative organisms

It's important to note that topical preparations used as prophylaxis against infection may themselves cause conjunctival irritation.

Prophylaxis:

Prophylactic measures to prevent neonatal conjunctivitis include:

• A single instillation of povidone-iodine 2.5% solution, which is effective against common pathogens.
• Administering silver nitrate 1% solution along with a single intramuscular dose of benzylpenicillin when maternal infection is present.

Mild conjunctivitis (commonly referred to as "sticky eye") is a frequent occurrence in neonates and may necessitate the use of a broad-spectrum topical antibiotic such as chloramphenicol or fusidic acid.

For moderate to severe cases, the following treatment approaches are recommended:

• Perform a Gram stain to identify the causative organism.
• Initiate treatment with a broad-spectrum topical antibiotic until sensitivities are available.

Specific treatment considerations include:

• For chlamydial infection, administer oral erythromycin for a duration of 2 weeks.
• Severe cases of conjunctivitis may require hospital admission for intensive management.
• Gonococcal conjunctivitis is typically treated systemically with a third-generation cephalosporin.

Acute Allergic Conjunctivitis

Acute allergic conjunctivitis is a common condition caused by an acute conjunctival reaction to an environmental allergen, typically pollen. It is often observed in younger children after playing outside in the spring or summer. Common symptoms include acute itching, excessive tearing, and severe chemosis.

Treatment is usually not required for acute allergic conjunctivitis. Cool compresses can be applied, and a single drop of adrenaline 0.1% may help reduce extreme chemosis.

Seasonal and Perennial Allergic Conjunctivitis

Seasonal and perennial allergic conjunctivitis are subacute conditions that differ in the timing of exacerbations:

• Seasonal allergic conjunctivitis: Often referred to as "hay fever eyes," it worsens during the spring and summer. The most common allergens are tree and grass pollens, although specific allergens may vary by geographic location.
• Perennial allergic conjunctivitis: This condition causes symptoms throughout the year, with exacerbations typically worse in the autumn. It is associated with exposure to house dust mites, animal dander, and fungal allergens.

Both types of allergic conjunctivitis present with transient acute or subacute episodes of symptoms, including redness, tearing, itching, sneezing, nasal discharge, conjunctival hyperemia, variable chemosis, and eyelid edema.

Treatment

Common treatment options for allergic conjunctivitis include:

• Mast cell stabilizers (e.g., sodium cromoglycate, nedocromil sodium, lodoxamide)
• Antihistamines (e.g., emedastine, epinastine, levocabastine, bepotastine)
• Oral antihistamines

Vernal keratoconjunctivitis is a recurrent bilateral disorder in which both IgE- and cell-mediated immune mechanisms play important roles. It typically manifests from about the age of 5 years onwards.

Ninety-five percent of cases remit by the late teens, while many of the remaining cases may develop atopic keratoconjunctivitis. Common symptoms of vernal keratoconjunctivitis include intense itching, excessive tearing, photophobia (sensitivity to light), a foreign body sensation, burning, and thick mucoid discharge.

Keratopathy, which refers to damage to the cornea, may also be present in some cases.

Management of Vernal Keratoconjunctivitis

Managing vernal keratoconjunctivitis involves several approaches to alleviate symptoms and prevent complications:

1. Allergen Avoidance: If possible, patients should avoid allergens that trigger their symptoms. Consultation with an allergy specialist may be beneficial. Allergen patch testing can provide insights but may yield non-specific findings.
2. Cool Compresses: Applying cool compresses to the affected eyes can provide relief.
3. Mast Cell Stabilizers: These medications help stabilize mast cells, reducing the release of histamine and other inflammatory mediators.
4. Antihistamines: Antihistamine eye drops or oral antihistamines may be prescribed to alleviate itching and other allergic symptoms.
5. Combined Preparations: Some medications combine mast cell stabilizers and antihistamines for comprehensive symptom relief.
6. Steroids: In severe cases, corticosteroid eye drops may be prescribed to reduce inflammation. However, long-term steroid use should be avoided due to potential side effects.
7. Immunomodulators: These medications can help modulate the immune response and reduce inflammation.
8. Systemic Treatment: In some cases, systemic medications like antihistamines or immunosuppressive agents may be necessary.
9. Surgery: Surgical options, such as bandage contact lenses and superficial keratectomy, may be considered for cases with corneal involvement.

Effective management typically involves a combination of these approaches, tailored to the individual patient's condition and symptoms.

Trachoma is a significant cause of infectious blindness worldwide and is associated with various social and environmental factors:

• Poverty, Overcrowding, and Poor Hygiene: Trachoma is closely linked to communities facing poverty, overcrowded living conditions, and inadequate hygiene practices. These conditions facilitate the establishment of re-infection cycles.
• Chlamydia trachomatis: The disease is caused by serological variants A, B, Ba, and C of the bacterium Chlamydia trachomatis.
• Immune Response: Recurrent infections trigger a chronic immune response characterized by cell-mediated delayed hypersensitivity (type IV).
• Vector and Transmission: Flies play a crucial role as vectors in trachoma transmission. However, direct transmission can also occur through eye or nasal discharge.
• Age Groups: Trachoma manifests differently in different age groups:
  • Active Trachoma: This form is most common in pre-school children.
  • Cicatricial Trachoma: Prevalence is highest in middle-aged individuals.

The prevention and control of trachoma involve addressing the underlying social determinants, improving hygiene, and implementing antibiotic treatments in affected communities.

Stages of Trachoma

WHO Grading of Trachoma

The World Health Organization (WHO) uses a grading system to assess the severity of trachoma. The grading includes the following stages:

1. TF (Trachomatous Inflammation - Follicular): This stage is characterized by the presence of five or more follicles (>0.5 mm) on the superior tarsus.
2. TI (Trachomatous Inflammation - Intense): TI stage involves the diffuse involvement of the tarsal conjunctiva, obscuring 50% or more of the normal deep tarsal vessels. Papillae are also present in this stage.
3. TS (Trachomatous Conjunctival Scarring): In this stage, easily visible fibrous white tarsal bands are present.
4. TT (Trachomatous Trichiasis): TT stage is characterized by at least one lash touching the globe, which can lead to corneal damage.
5. CO (Corneal Opacity): This stage involves corneal opacity that is sufficient to blur details of at least part of the pupillary margin.

The WHO grading system helps healthcare professionals and organizations assess and monitor the severity of trachoma cases, enabling targeted interventions and treatment to prevent further complications.

Pingueculum is a common ocular condition characterized by usually bilateral and asymptomatic 'elastotic' degeneration of the collagen fibers in the conjunctival stroma.

Treatment for pingueculum is usually unnecessary because the growth of this condition is very slow or absent. However, in some cases, it may become acutely inflamed, a condition known as pingueculitis, which may require a short course of a weak steroid to alleviate symptoms.

Pterygium is a triangular fibrovascular subepithelial ingrowth of degenerative bulbar conjunctival tissue that extends over the limbus and onto the cornea. It typically develops in patients living in hot climates and is considered a response to factors such as UV exposure and chronic surface dryness.

• May be asymptomatic.
• Common symptoms include irritation and grittiness, interference with vision by obscuring the visual axis or inducing astigmatism, intermittent inflammation similar to pingueculitis, and cosmetic concerns.
• Medical treatment options include tear substitutes and topical steroids for inflammation.
• Patients may also be advised to wear sunglasses to reduce ultraviolet exposure and decrease the growth stimulus.
• Surgical excision may be considered for more severe cases.

• Retention/inclusion cysts are thin-walled lesions containing clear or sometimes turbid fluid.
• They may be asymptomatic, causing no discomfort, and are primarily a cosmetic blemish.
• Management may involve puncture with a needle. When puncturing, approach the cyst with the needle tangentially rather than perpendicular to the globe. If puncture fails or is not preferred, cyst wall excision under topical anesthesia can be considered.

Blistering Mucocutaneous Diseases (BMDs)

BMDs are a group of rare disorders that cause blisters to form on the skin and/or mucous membranes. The mucous membranes are the thin, moist tissues that line the inside of the body, such as the mouth, nose, throat, and genitals.

Superior Limbik Keratoconjunctivitis (SLK)

SLK is a rare BMD that affects the eyes. It is characterized by the formation of blisters on the conjunctiva, which is the thin membrane that lines the eyelids and covers the white part of the eye. The blisters can rupture and cause pain, redness, and inflammation. SLK can also lead to vision problems.

Other BMDs Affecting the Eyes

• Ocular Cicatricial Pemphigoid (OCP): An autoimmune disease that causes blisters to form on the conjunctiva and cornea, the clear front part of the eye. OCP can lead to scarring and vision loss.
• Stevens-Johnson Syndrome (SJS) and Toxic Epidermal Necrolysis (TEN): Two rare and serious skin disorders that can also affect the eyes. SJS and TEN can cause blisters to form on the conjunctiva and cornea, and can lead to scarring and vision loss.
• Behçet's Disease: A chronic autoimmune disease that can cause inflammation in various parts of the body, including the eyes. Behçet's disease can cause a variety of eye problems, including uveitis (inflammation of the inside of the eye) and retinal vasculitis (inflammation of the blood vessels in the retina).