Filtration bleb
Conjunctival elevation created after glaucoma filtering surgery to allow aqueous humor drainage.
Full Definition
A filtration bleb is a localized conjunctival elevation that forms following glaucoma filtering procedures such as trabeculectomy or tube shunt surgery. The bleb serves as a reservoir for aqueous humor that has drained from the anterior chamber through the surgical fistula. Successful blebs appear diffuse, thin-walled, and moderately elevated, while failing blebs may become encapsulated, fibrotic, or leak. Bleb morphology is assessed using clinical examination and imaging to determine filtration success. Complications include bleb-related infections, hyperfiltration with hypotony, and late bleb failure requiring revision surgery.
Usage
Usage note: Bleb morphology descriptions should be specific (diffuse vs. encapsulated, thin-walled vs. thick-walled) for accurate clinical documentation.
In Context
- "The filtration bleb appeared well-formed and diffuse at the one-month postoperative visit." — Clinical note
- "Encapsulated filtration blebs often require needling or revision surgery to restore function." — Surgical planning