Dear Dr. K: My brother has vernal conjunctivitis and I have perennial allergic conjunctivitis. We both use the same eye drops but I seem to do a lot better than he does. What gives?
What gives is that you have a less severe condition than your brother. Let me explain. Allergic eye problems fall into four general types: seasonal allergic conjunctivitis (SAC), perennial allergic conjunctivitis (PAC), allergic keratoconjunctivitis (AKC) and vernal keratoconjunctivitis (VKC).
IgE (the allergic protein), plays a role in all four, but in ARC and VKG T-lymphocytes (the allergic cells) also contribute to the mischief. (Unlike in the familiar “pink eye,” caused by a virus or bacteria and not by allergy.)
SAC is probably the most common and is seen at all ages and equally in males and females. It is caused by seasonal pollens: ragweed in Fall, trees in Spring and grasses in summer. It responds better to eye drops than to oral antihistamines. The eye drops most commonly used are topical antihistamines or mast-cell stabilizers (mast cells release histamine).
PAC is also very common with the same age and gender distribution as SAC. Because it is perennial, it is usually caused by pet dander allergy, but also by dust mite and mold allergy. It responds to the same treatments as SAC.
In both SAC and PAC, the most common symptom is itching, but the eyes also tear, burn and can turn red. The eyelids can swell, but this is usually caused by unrestrained rubbing of the eyes – especially in young children.
Luckily, AKC is an uncommon allergy as it can be quite severe and adversely affect vision. This one is more frequent in males and more common in middle age. Most of these patients have eczema, and the eye symptoms often wax and wane with their skin symptoms. There can also be eczema surrounding the eyes, as well as other body areas. The eyes itch and tear, but also tend to produce a mucus discharge. The inside of the eyelids – more on the lower lids than the uppers – develop little bumps.
Antihistamine and mast-cell stabilizer drops are helpful. In severe cases, steroid eye drops are sometimes used to gain control of the problem but should only be used short-term. Cyclosporine eye drops and tacrolimus ointment to the external lids are also of benefit. Both medicines work on the T-cell part of the inflammation.
VKC (just as AKC) is perennial but can worsen in Spring — hence the name vernal as in vernal equinox. Eyes itch and turn red. This redness tends to be greatest on the white part of the eye right next to the iris. As in AKC, the inside of the eyelids develops bumps, but these tend to be worse on the upper lids. The eyes tear and also produce a ropey mucus discharge. It is most common in males but at a younger age: pre-teen and teen. It is treated the same way as AKC.