Allergic Conjunctivitis Flashcards
Allergic Conjunctivitis
acute care / chronic care
cool compresses
OTC vasoconstrictor/antihistamine combo gtt
Rx antihistamines, dual mechanism Rx, steroid gtt
OTC / Rx antihistamines, antihist/decongestant combo PO “sedating” and “non-sedating“ PO
anticipate allergy season with Rx mast cell stabilizer gtts
symptoms
itchy, watery, tearing, red scratchy, FB sens
lids “matted shut in AM” swollen?
signs
thin watery discharge redness
AM crusting of lashes from drying of tears, serous secretions palpebral conjunctival papillae
conjunctival injection
conjunctival chemosis?
red and edematous eyelids? no preauricular nodes (PAN)
pathophysiology
- an allergic response is a reaction of the body’s immune system to foreign substances known as allergens which the body perceives as a potential threat
- the response can be innate (present from birth and nonspecific in activity) or adaptive (acquired memory of and specificity against the same or closely related foreign agent previously encountered)
What does the presence of an allergen on the conjunctiva initiate? (2)
- the release of“pre-formed”inflammatory mediators such as histamine from mast cells
- the production of arachidonic acid and its conversion into“newly-formed”mediators such as prostaglandins
mast cell degranulation
allergen attracts and binds to IgE then adheres to mast cells causing them to degranulate
what do histamine and bradykinin stimulate?
nerve endings (nociceptors)
What creates sensation of itching?
histamine and bradykinin
What increases vascular permeability and vasodilation?
histamine and bradykinin
What does vascular permeability and vasodilation cause?
redness and conjunctival injection
What do all cells contain in their cell walls?
phospholipid layer
What does threat and disruption signal?
Cells convert phospholipids into arachidonic acid
What is arachidonic acid metabolized into?
prostaglandins
thromboxanes
leukotrienes
What does an allergen’s presence initiate?
arachidonic cascade within conjunctival epithelial cells and within mast cells as they degranulate
What do leukotrienes attract?
WBCs (macrophages)
treatment options
decrease symptoms/signs
- topical allergy medications
- oral antihistamines
OTC treatment
benadryl (diphenhydramine)
chlor-trimeton (chlorpheniramine)
benadryl (dosage and age)
25, 50 mg q4-6h (12y)
Chlor-Trimeton (dosage and age)
2,4,6,8, 12 mg q4-12 h [< or = 24 mg/24h] (12 y)
Rx
Claritin, Alavert
Clarinex
Allegra
Zyrtec
Claritin
loratadine
5mg BID,10mg qD,1mg/ml(>6y); 5mg qD(2-6y)
Clarinex
desloratadine
5mg (12y)
cool compresses
a. cool compresses STRONGLY indicated for allergy; vasoconstriction reduces
chemosis
b. after success decreasing itch with cool compresses (1-3 days?), patient could
experiment with warm compresses which might reduce chemosis by promoting drainage from vasodilation (may also worsen)
reduce serous leakage
a. topical decongestants (can cause rebound hypermia) 7
ii. naphazoline (Naphcon, Albalon, Vasocon, etc.)
b. oral decongestants
i. pseudoephedrine 30,60 mg / 120,240 mg extended-release
c. oral anti-histamine + decongestant
i. loratadine 5mg + pseudoephedrine 120mg (Claritin-D Rx)
ii. chlorpheniramine 4 mg + pseudoephedrine 60 mg
topical steroids
generally indicated for severe conditions with symptoms and signs
b. provide a quick fix for minor allergies
c. prone to overuse by the patient
d. prone to over-prescribing by the doctor
e. potential danger of masking infection and/or inducing glaucoma
Regimen of Treatment (in increasing order of therapeutic efficacy for increasingly severe allergic conjunctivitis)
a. cool compresses as much as needed
b. OTC topical vasoconstrictors, ≤QID (can cause rebound hyperemia)
c. OTC topical vasoconstrictor/antihistamine combination drops (Naphcon-A, Opcon-
A, Vasocon-A, etc.) (can cause rebound hyperemia)
i. may work synergistically, responses are idiosyncratic, dosage QID
d. topical anti-histamines
e. topical dual mechanism (anti-H and MCS)
f. topical steroid drops - TID to QID
i. use only when urgently indicated
ii. short term course only
g. oral antihistamines
h. oral antihistamine/decongestant combinations, BID to QID
(primarily for seasonal rhinitis sufferers with allergic conjunctivitis)
i. mast cell stabilizers (MCS)
i. anticipate start of allergy season by 3-4 weeks
ii. QID regimen
iii. for chronic allergies only (not acute attacks)
j. avoid allergen(s) whenever known and possible
Patient communication
• trying to decrease symptoms
• discover / prevent exposure to allergen?
• pre-treat seasonal allergies weeks in advance of allergy season
[mast cell stabilizers QID or OTC ketotifen (Zaditor) BID or Rx olopatadine (Patanol BID / Pataday qD)
