Allergy season is here
Allergy season is here again and when you think about ocular allergies, what are the first symptoms that come to mind?
Usually, we think of someone complaining about their itchy, red, and watery eyes.
But what causes these symptoms? Histamine!
We all think of histamine as being the bad guy, but in truth, it is all part of our body’s immune response. Without it, the body wouldn’t respond appropriately to foreign invaders like pollen, dust, and pet dander. The issue with ocular allergy and any other allergic response is an overreaction of our immune system that can lead to an enormous histamine release and an inflammatory cascade. Inflammation is an evolutionary defense mechanism developed by higher organisms to prevent injury and infection.1
Histamine resides within mast cells. When the offending allergen, such as saliva from a mosquito bite, enters the body, it leads to a type I hypersensitivity reaction. The allergenic protein residing in the saliva of female mosquitoes is deposited during its blood meal which triggers the histamine-containing mast cells to release. The histamine, in turn, is what causes the raised bump (also known as a wheal, see Figure 1) and itch. If you scratch that itch, it will cause more mast cell degranulation and release which will lead to more histamine release. You will feel better initially, but the area of wheal will grow as a response to the scratching, thereby delaying the resolution of the bite. If you have enough willpower not to think about the itch, your body will thank you later.
So don’t scratch that itch! Find something else to distract yourself.
Let’s do a quick review of the four different types of allergic reactions:
1. Type 1 – Acute “immediate” (e.g., Asthma attack, allergic conjunctivitis)
2. Type 2 – Cytotoxic (e.g., Graves disease)
3. Type 3 – Immune complex (e.g., Systemic Lupus Erythematous)
4. Type 4 – Delayed hypersensitivity (e.g., Contact dermatitis, Stevens-Johnson syndrome)
Think you have ocular allergies or even just red eyes? Make an appointment with our doctors to review the latest treatments including some great new over the counter options that have only been available by prescription in the past.
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