Ophthalmology Quiz: Conjunctivitis & Blepharitis

Eye Pathology P1

• Covers conjunctival and corneal pathologies, and disorders of the eye appendages.

Outcomes

• Describe the pathophysiological processes underlying main eye illnesses (cataracts, keratitis, blepharitis, conjunctivitis, hypopyon, chalazion) and relate them to their clinical features.

Eyelid/Conjunctival Anatomy and Histology

• The eyelid, conjunctiva, and associated structures (lacrimal apparatus) are known as the ocular adnexa.
• The conjunctiva is a mucous membrane covering the interior surface of the eyelids (palpebrae) and the anterior aspect of the sclera (bulbar conjunctiva).
• The palpebrae have a complex structure, including skin on the outer surface, conjunctiva on the inner surface, and the tarsus (fibroelastic connective tissue).
• Cilia (lashes), sebaceous glands, and sudoriferous glands are associated with the lid margin.
• The orbicularis oculi muscle (CN VII) and levator palpebrae muscles (SNS innervation) are beneath the skin.
• Meibomian glands are modified sebaceous glands in the tarsus, contributing to the tear film.
• Glands of Zeis are small modified sebaceous glands that open into the hair follicles at the base of the lashes.
• Glands of Moll are modified sweat glands that open near the base of the lashes.
• Accessory lacrimal glands are also present.

Conjunctivitis - Overview

• Types of conjunctivitis include:
  • Infectious (bacterial, viral, chlamydial, gonococcal, parasitic, fungal)
  • Immune-mediated (allergic, atopic, vernal)
  • Irritants (dust, smoke, toxins, chemicals).

Bacterial Conjunctivitis

• A common infection caused by staph aureus, Strep pneumoniae, Chlamydia trachomatis, or Neisseria gonorrhoea.
• Staph aureus and Strep infections are frequently self-limiting.
• Chlamydial and gonorrheal infections can cause conjunctival scarring and potentially blindness.
• Scarring can eliminate goblet cells in the conjunctiva's fornix.
• Loss of mucous production results in tear film detachment from the cornea, leading to corneal irritation and scarring.
• Bacterial conjunctivitis generally has a shorter duration and more purulent discharge compared to viral conjunctivitis.

Viral Conjunctivitis

• A very common infection, typically caused by adenovirus, and can also be caused by herpes or varicella viruses.
• Viral infections are highly contagious and self-limiting.
• Antiviral medications can help infections with herpes or varicella.
• Characterized by redness, swelling, excessive tearing, and a longer duration of symptoms compared to bacterial conjunctivitis.

Clinical Features - Infectious Conjunctivitis

• Common clinical features include red eye (conjunctival injection), itchy eyes, sensation of foreign body, tearing, discharge, morning crusting of lashes, and involvement of pre-auricular and/or submandibular lymph nodes (more common with bacterial).
• Allergic and atopic conjunctivitis may be associated with rhinitis and asthma.
• Chemosis (swelling of the conjunctiva) is often more significant with these types of conjunctivitis.

Selected types of conjunctivitis

• Gonorrheal and chlamydial conjunctivitis require urgent treatment to prevent extensive damage and corneal damage.
• Trachoma, a chlamydial infection, is a significant cause of blindness globally.
• Severe inflammation of the conjunctiva and cornea can lead to corneal abrasion, ulceration, and scarring.
• Large follicles (enlarged lymphatic tissue) can be present in the superior palpebral conjunctiva (often seen with viral).

Conjunctivitis findings

• The "bumpies" in the conjunctiva (follicles) are seen in viral and chlamydial conjunctivitis.
• Papillae are seen with allergic and bacterial conjunctivitis

Blepharitis

• Inflammation of the eyelids; it can have multiple causes, including:
  • Purulent infection, such as styes (hordeolum).
  • Seborrheic dermatitis.
  • Allergic, drug toxicity, or autoimmune disease (Sjogren syndrome).
  • General infections, such as herpes or varicella viruses.

General Clinical Features of Blepharitis

• Redness, itching, and irritation of the eyelids (one or both).
• Dry or gritty feeling in the eyes.
• Often confused with conjunctivitis, especially in older individuals
• Untreated blepharitis, particularly ifrosacea-related, can lead to conjunctivitis
• Severe cases can result in corneal inflammation and scarring.

Infections of the eyelid

• Hordeolum (sty): a purulent bacterial infection of a sebaceous or sudoriferous gland (usually a Meibomian gland).
• Typically caused by Staphylococcus aureus.
• Small, inflamed, tender bumps appear at the eyelid margin.
  • Often self-resolving with warm compresses and good hygiene.
• Chalazion: a granulomatous inflammation, not infectious, caused by blocked or broken-down sebaceous gland secretions (meibomian gland).
• Benign, generally treated with heat and massage.
• May require antibiotics in some cases.

Keratitis

• Inflammation of the cornea, often caused by herpes simplex virus type 1 (HSV-1, common cause of cold sores) or HSV-2 (genital herpes).
• Initial infection may not be severe damage, but reactivation can cause a more severe reaction and corneal ulceration.
• Reactivation of HSV may be associated with stress, excessive sunlight exposure, and fluctuations in reproductive hormones.

HSV Keratitis

• HSV-1 or HSV-2 can cause many small intraepithelial ulcerations.
• Inflammatory reaction to HSV in the cornea causes ulceration and may cause scarring and edema of the stroma and abnormalities of the corneal endothelium.
• Clinical features typically include pain, tearing, foreign body sensation, red eye, and potentially decreased vision.
• Herpes-zoster ophthalmicus (HSV-3), typically unilateral, may cause severe complications including keratitis, ulceration, and scarring, along with secondary iritis, glaucoma, cataract, and post-herpetic neuralgia.

Test your knowledge on various conditions related to conjunctivitis and blepharitis. This quiz covers symptoms, causes, and potential consequences associated with these eye disorders. Ideal for students in ophthalmology or general medical fields.