Background
Our study aims to identify anatomical characteristics of glaucoma filtering blebs by means of slit lamp-adapted optical coherence
tomography (SL-OCT) and to identify new parameters for the functional prognosis of the filter in the early post-operative
period.
Methods
Patients with primary open-angle glaucoma, aged 18 years and older, scheduled for primary trabeculectomy at the Department
of Ophthalmology, Radboud University Nijmegen Medical Centre, were considered for our study. All patients underwent standardized
trabeculectomy with intra-operative application of mitomycin C. The filtering blebs were evaluated clinically and with SL-OCT
on day 1 and 1, 2, 4 and 12 weeks following surgery. The resulting data were analysed and weighed against surgical success.
To better understand the SL-OCT data a small comparative histologic study was performed.
Results
The study included 20 eyes of 20 patients. After completion of our study, 15 eyes of 15 patients (mean age±SD 67 ± 16 years)
were eligible for data analysis and 5 eyes missed at least one follow-up visit. Filtering surgery was considered successful
(intraocular pressure ≤ 21 mmHg without antiglaucomatous medication) in 11 of 15 eyes. SL-OCT frequently demonstrated multiple
hypo-reflective layers within Tenon’s capsule (“striping” phenomenon) in the first post-operative week. Presumably, these
layers corresponded with drainage channels in the histological specimen. These channels were present in functional filters
but not in the failures. In addition, the visualisation of the sclera below the filtering zone was better defined in failures
compared with successful filtering blebs (“shading” phenomenon). We observed no differences in the volume and clinical aspect
of the blebs in the successful group compared with the unsuccessful group.
Conclusions
Successful filtering blebs show characteristic optical properties on SL-OCT. These phenomena suggest a diffusely enhanced
fluid content and the presence of intra-bleb drainage channels in functional filtering blebs.
Keywords Trabeculectomy - Optical coherence tomography - Prospective study
Meeting presentation Presented in part as a poster at the 1st World Glaucoma Congress, Vienna, Austria, July 2005.
Financial disclosure Medical Workshop, Groningen, Netherlands, made the slit lamp-adapted optical coherence tomography device available to one
of the authors (T. Theelen) with support from the manufacturer, Heidelberg Engineering, Lübeck, Germany. There are no other
competing interests.