Week 5 - Allergic conjunctivitis

Question 1

Hypersensitivity reactions:

Answer 1

• 4 types of Hypersensitivity reactions
- Type 1 (IGE mediated)
- Type 2 (cytotoxic)
- Type 3 (immune complex)
- Type 4 ( Delayed hypersensitivity)

• In terms of allergic eye disease Types 1 and 4 and most relevant

Question 2

Type 1 Hypersensitivity reactions:

Answer 2

• IgE mediated
• IgE antibody produced after 1st exposure to an allergen (antigen)
• IgE molecules bind to mast cell and basophils causing the release of histamine and other inflammatory mediators
• Causes smooth muscle contractions, vasodilation, increased mucous secretion and increased blood vessel permeability

Question 3

Type 4 :

Answer 3

• Mediated by T cells
• Symptoms present 48-72 hours after exposure to the allergen (antigen)
• Antigens attach to t cells causing the release if cytokines which attract lymphocytes macrophages and basophils to the affected area

Question 4

Signs + Symptoms common to allergy subtypes:

Answer 4

• Itching - Hallmark of Allergy
• Redness - (hyperaemia of the lids and conjunctiva)
• Swelling - (chemosis of the lids and conjunctiva)
• Discharge - (consistency and amount varies)

Question 5

Subtypes of ocular allergy

Answer 5

• Acute Ocular Allergy (Acute Allergic Conjunctivitis)
• Seasonal and Perennial Allergic Conjunctivitis
• Vernal Keratoconjunctivitis
• Atopic Keratoconjunctivitis
• Contact Lens Associated Papillary Conjunctivitis

Question 6

Difference between Papillae and Follicles:

Answer 6

• Pappillae
- Central vascular core (red centres)
- flat topped projection
- Can be larger e.g. cobblestone >1mm in diameter
- Typically most prominent in the “central” palpebral conjunctiva

• Follicles
- Lack a prominent central vessel (red at the base, pale at the centre)
- Dome shaped nodules -
- Always small
- Typically most prominent in the forniceal conjunctiva

Question 7

Acute Allergic Symptoms:

Answer 7

• Presentation: Sudden onset

• Discharge: Slight watery discharge

• Itch: Itching, can be unilateral

• Associated symptoms: Sudden eyelid swelling

• Seasonal:

Question 8

Seasonal/Perennial:

Answer 8

• Presentation:

• Discharge: Watery discharge

• Itch: Itching

• Associated symptoms: Associated Rhinitis

• Seasonal:
- Seasonal - Onset based on allergen - tree pollen - spring; grasses - early summer; weeds and fungal spores - late summer

• Perennial - throughout the year with seasonal exacerbations

Question 9

CLAPC:

Answer 9

• Presentation: CL wearers only

• Discharge: Mucus discharge

• Itch: Itching and irritation, may be worse on lens removal

• Associated symptoms: Poor CL tolerance

• Seasonal:

Question 10

VKC:

Answer 10

• Presentation: Presents in first decade, typically resolves at puberty

• Discharge: Mucoid stringy discharge and watering

• Itch: Severe itch, asymmetrical symptoms

• Associated symptoms:

• Seasonal: Seasonal Exacerbations

Question 11

AKC

Answer 11

• Presentation: Affects people from late 20’s - 50’s

• Discharge: Mucoid stringy discharge (white) and watering

• Itch: Severe bilateral itching, burning

• Associated symptoms:

• Seasonal: Year round with seasonal exacerbations

Question 12

Differential Diagnosis

Answer 12

• Ensure you don’t just limit it to allergic conjunctival conditions
• Depending on the individual case presentation you may also want to include conditions also causing a red or irriated eye such as:

• Infective conjunctivitis
• Dry eye
• Foreign bodies
• Episcleritis