BLOG: What is blebitis?
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The patient had a bright white bleb and a bright red eye, like some kind of inverse Japanese flag. His vision had dropped to counting fingers, and he had 1+ cell and 2+ flare in the anterior chamber and a mild vitritis.
When I asked if it hurt, he said a little, but it wasn’t bad. He was a veteran of the Korean War. He was light perception in the other eye from advanced glaucoma, so his wife guided him into the exam chair, and he apologized to me when he bumped into the slit lamp.
I made the diagnosis of blebitis in the right eye with severe concern for endophthalmitis. I spoke to the two of them about the seriousness of the condition and told them he needs to be seen emergently in an ophthalmology clinic downtown. His face fell, and he looked toward his wife, who looked at the ground. He said his wife did not like to drive downtown.
Blebitis can be a sneaky diagnosis. I’ve seen three in my career, and each time I thought about the last one when I made the diagnosis. The first time I saw one, I thought it was just a regular uveitis, as the injection wasn’t too bad. Then the patient came back the next day with a shockingly white bleb compared to the surrounding redness of the conjunctiva and sclera, and the diagnosis became clear.
The name blebitis is a kind of portmanteau describing an infection that begins in a filtering bleb. Remember that when we make a bleb for glaucoma management, we are making a hole in the sclera and covering it with conjunctiva. This means that the only protection of the anterior chamber from the bacteria on the ocular surface is a thin layer of conjunctiva, which gets thinner with age and thinner if antimetabolites (eg mitomycin C) were used in the trabeculectomy surgery. So, the logic goes that if the bleb is leaking aqueous, there is an open communication to the anterior chamber; given the pressure differentials, bacteria on the surface could easily enter the anterior chamber.
What strikes me in this condition is the stark color difference: the red and the white. The red makes sense – an angry eye, very inflamed, dilated vasculature due to the immune response to the infection. The white is more interesting. Regular blebs look white because there can be an avascularity in the part of sclera involved in the bleb. But the whiteness of a blebitis is different; it’s more opaque. This is because the infection is giving off a mucopurulent discharge. Pus is forming in the bleb and creating a milky-white coloration, which is in striking contrast to the angry red of the adjacent ocular surface.
A blebitis is a very serious infection typically treated with fortified antibiotics. But if the vitreous is involved, the diagnosis is often a bleb-associated endophthalmitis, which is a much more serious infection and requires much more invasive management. If an endophthalmitis is suspected (ie, if the vitreous has inflammation), the vitreous should be cultured and antibiotics started as soon as possible. The longer the infection lasts, the worse the prognosis for visual recovery. Antibiotics are usually given locally, as there is slow penetrance of systemic antibiotics to the vitreous.
There are two schools of thought for obtaining cultures and starting treatment: vitrectomy vs. tap and inject. A vitrectomy would obviously remove all of the vitreous, allowing for more medium to culture, and would also reduce the amount of infecting organisms, toxins, inflammatory materials and opacities. However, a vitrectomy takes operating room access, which is not an easy thing to do in an emergency. Also, vitrectomized patients clear intravitreal antibiotics faster, which reduces the time the antibiotic is in place. Tap and inject is the phrase used for inserting a needle into the vitreous chamber to draw up a culture (tap) and then injecting medication – usually antibiotics. Once the cultures come back, therapy can be further tailored to the offending agent.
Try to remember the possibility of blebitis in your patients with a bleb. Even if everything seems fine, even if it’s been years since the surgery, use a fluorescein strip to check for a wound leak. Don’t underestimate the presence of any cells in the anterior chamber. Follow these patients very closely and have a low threshold to refer the patient to a surgeon. Remember that when a patient has a bleb, the structural integrity of the eye is forever changed, and the eye’s response to an antigen might not follow the usual rules. Look for a white infiltrate in the bleb, look for a mild cellular reaction in the anterior chamber, look for an unexplained conjunctival injection. Time is of the essence in fighting blebitis.
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