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Bleb infections and leaks are vision-threatening complications that require rapid and aggressive treatment, according to Sunita Radhakrishnan, MD.
"You have to remind patients about this, because they may not correlate symptoms they're having now to a surgery they had 5 years ago," said Dr. Radhakrishnan, research director of the Glaucoma Research and Education Group in San Francisco.
She presented an overview of bleb complications at Glaucoma 360, the annual meeting of the Glaucoma Research Foundation.
Although the frequency of trabeculectomy is declining since the advance of minimally invasive glaucoma surgery, the role for trabeculectomy persists, said Dr. Radhakrishnan. And newer subconjunctival filtration procedures still create blebs and require the use of mitomycin.
She recommended educating office staff members who handle patients' phone calls to ask about a history of glaucoma surgery if the color reports complaints of redness, blurry vision, pain, tearing, discharge or light sensitivity. Patients with these symptoms who have had glaucoma surgery should get emergent appointments, said Dr. Radhakrishnan.
She divided bleb-related infections into the categories of blebitis and bleb-related endophthalmitis.
Blebitis causes redness, tearing or discharge, pain or discomfit, blurry vision and swollen lids, she said. It has a white-on-red appearance with a spillover anterior chamber reaction, and clear vitreous. Seidel testing is often positive.
As management for blebitis, she recommended hourly fluoroquinolone eyedrops (after a loading dose) with a possible antibiotic ointment at night.
"These patients need very close follow-up, daily if necessary, until improvement is evident," said Dr. Radhakrishnan.
Oral antibiotics help in some cases, such as a third generation quinolone. With these measures, the prognosis is good. She errs on the side of aggressive treatment.
If the vitreous is not well-visualized, or if the diagnosis of isolated blebitis is in doubt, she recommends treatment of the bleb as potential endophthalmitis.
Bleb-related endophthalmitis can occur years after filtering surgery, she said, listing such risk factors as a cystic and avascular bleb appearance, an inferior bleb, a bleb leak, use of antimetabolites, intermittent or chronic use of antibiotics beyond the initial post-operative period and blepharitis.
Endophthalmitis has a rapidly progressive presentation, said Dr. Radhakrishnan. It often includes worsening pain, redness and decreased vision over a period of hours. Vitritis is the defining feature, she said. Streptococcus and H. Influenzae are the organisms most often to blame.
Most patients with bleb-related endophthalmitis lose 4 or more lines of visual acuity with outcomes ranging from counting fingers to light perception in many cases.
Even after the infection resolves, complications may include loss of bleb function, corneal edema, cataract progression and vitreoretinal complications.
If bleb-related endophthalmitis is suspected, the patient should be referred immediately to a vitreo-retinal specialist.
Bleb leaks are associated with an increased risk of bleb-related endophthalmitis, said Dr. Radhakrishnan. Thin and avascular blebs, especially after antimetabolites, are at risk for late leaks. Patients may be asymptomatic or present with tearing and changes in vision, she said.
"There is no hard and fast rule telling us when to fix a bleb leak," said Dr. Radhakrishnan. Non-incisional management includes topical antibiotics with aqueous suppressants, bandage contact lenses cyanoacrylate glue, trichloroacetic acid therapy, cryotherapy, argon laser photocoagulation, thermal bleb revision, bleb compression suturing, autologous blood injection and bleb needling to direct the flow posteriorly.
Surgery is the definitive treatment for a leaking bleb, Dr. Radhakrishnan said, but a recurrent leak and bleb failure may still occur. The many surgical techniques include conjunctival advancement with or without bleb excision, free conjunctival graft, tenon graft, amniotic membrane and buccal mucosal membrane.