Pathophysiology of ocular allergy Flashcards
What is the immune system?
- Defence system of the body against pathogenic microbes in environment
- collection of cells and molecules
- inflammation : kills microbes
What is an allergy?
Immune system inappropriately triggered/not properly controlled
- abnormal immune response to commonly encountered antigens
- manifested as inflammation
What are the two types of immunity?
-Innate and adaptive
What is innate immunity?
Prevents & controls majority of infections
- always present
- mediated by cells & proteins
e.g. epithelial barriers, phagocytic leucocytes, natural killer cells, circulating plasma proteins of the complement system
What is adaptive immunity?
more powerful & specialised mechanism
- it responds to presence of infectious microbes by activating, expanding and generating potent mechanism
What are the two types of adaptive immunity?
Humoral
Cellular
What is humoral immunity?
- B lymphocytes : produce antibodies
- defence against extracellular microbes (blood, mucosal secretions & tissue)
What is cellular immunity?
- T lymphocytes
- defence against intracellular microbes
- either kill infected cells or activate phagocytes to kill ingested microbes
What are the causes of hypersensitivity reactions?
- reactions against environmental antigens
- reactions against microbes
- autoimmunity
What is Vernal Conjunctivitis?
Sight-threatening, bilateral, chronic allergic inflammation of the ocular surface
What are symptoms of vernal conjunctivitis?
Worst from spring to fall (severe itching, photophobia, tearing & mucus discharge)
What is atopic conjunctivitis?
sight threatening, bilateral, chronic allergic inflammation of the ocular surface & eyelids associated with atopic dermatitis
What are signs and symptoms of atopic conjunctivitis?
chronic itching, burning, tearing, photophobia, papillary hypertrophy, conjunctival hyperemia, chemosis, swollen eyelids
What is contact allergy?
Hypersensitivity response
- ocular surface, eyelids & periocular skin
What are the signs of contact allergy?
Dermatitis of the periocular skins & eyelids, itching, conjunctival hyperemia, chemosis, follicular/papillary reaction
