Filtering bleb functionality: a clinical, anterior segment optical coherence tomography and in vivo confocal microscopy study

J Glaucoma. 2008 Jun-Jul;17(4):308-17. doi: 10.1097/IJG.0b013e31815c3a19.


Purpose: To provide a microscopic and macroscopic analysis by a clinical, in vivo confocal microscopy (IVCM) and anterior segment optical coherence tomography (AS-OCT) assessment of filtering blebs after glaucoma surgery.

Material and methods: We retrospectively analyzed 60 eyes of 48 glaucomatous patients by slit-lamp, IVCM, and AS-OCT examinations. Patients were divided into 2 groups: successful blebs (group 1, 16 patients, 27 eyes) were defined as a one-third reduction in preoperative intraocular pressure without antiglaucoma medications and failed blebs (group 2, 32 patients, 33 eyes) as a less than one-third reduction in preoperative intraocular pressure without therapy. The examinations were performed from 1 to 96 months postoperatively.

Results: Diffuse or cystic clinical patterns were indicative for good functionality whereas flat or encapsulation was indicative for poor functionality. When comparing successful with failed blebs, the IVCM analysis showed a greater number (P=0.014), density (P=0.009), and total area of epithelial microcysts (P=0.017) and a lower density of connective tissue (P=0.006). The AS-OCT analysis showed a lower degree of bleb wall reflectivity (P<0.001). A significant correlation was found between the clinical and AS-OCT parameters, particularly for the cystic (100%) and diffuse (74%) patterns.

Conclusions: All IVCM parameters did correlate well with the bleb functionality whereas, among the AS-OCT parameters, only the bleb wall reflectivity was significantly related to the filtering capability. Clinical and AS-OCT bleb classification showed a significant degree of concordance. As a consequence, simultaneous approach by clinical, microscopic, and tomographic assessment improves the clinician's ability in the postsurgery understanding and management of blebs.

Publication types

  • Comparative Study

MeSH terms

  • Aged
  • Anterior Eye Segment / pathology*
  • Aqueous Humor / metabolism
  • Blister / diagnosis*
  • Conjunctiva / physiology*
  • Female
  • Glaucoma, Open-Angle / surgery
  • Humans
  • Intraocular Pressure
  • Male
  • Microscopy, Confocal*
  • Middle Aged
  • Retrospective Studies
  • Surgical Flaps / physiology*
  • Tomography, Optical Coherence*
  • Tonometry, Ocular
  • Trabeculectomy