Abstract
Purpose: :
To investigate the relationship between drainage tube position within the anterior chamber (AC), changes in corneal endothelial cell morphology, intraocular pressure (IOP) and size/morphology of the subconjunctival drainage area (SDA) in glaucomatous patients implanted with Baerveldt glaucoma aqueous shunt.
Methods: :
25 eyes from 21 consecutive Caucasian patients with different phenotypes of refractory glaucoma were enrolled in a prospective, single-centre study. All the eyes underwent superotemporal placement of a Baerveldt 350-mm2 aqueous shunt within the same period (2005) and completed a postoperative follow-up of 24 months. The participants received a corneal specular microscopical evaluation with KONAN NONCON ROBO model SP-9000 (Konan Medical Inc., Hyogo, Japan) in the preoperative period and 24 months after surgery. Ultrasound biomicroscopy with UBM model 840 (Zeiss-Humphrey Inc., San Leandro, CA, USA) was used to analyse the position of the tube within the AC. B-scan echography with I3-System-ABD (Innovative Imaging Inc., Sacramento, CA, USA) was performed to measure the size and to evaluate the morphology of the SDA. Both echographical evaluation were performed 24 months after surgery. The main outcome measures included: central corneal thickness (CCT), endothelial cell density (ECD), co-efficient of variation (CV), percentage of hexagonal cells (6A); tube-corneal angle (TCA), tube-length (TL), distance from tip of tube to endothelium (TED) and lens (TLD); transverse height (TH) and width (TW), longitudinal height (LH) and width (LW), morphology (low or high-relfective) of the SDA.
Results: :
There was a significant mean reduction (28%) of ECD after surgery (p=0.003). The analysis showed a correlation between TCA and TW (r=0.507; p=0.01) of the SDA. Multiple regression analysis failed to establish any relationship between tube position within the AC, corneal endothelial morphology and size/morphology of the SDA 24 months after surgery. There was no difference between tube position and size/morphology of the SDA in terms of postoperative IOP value.
Conclusions: :
Although the surgical insertion and the presence of a drainage tube within the AC may have a significant negative influence on ECD, tube position does not correlate with long-term corneal endothelial function. The positive correlation between TCA and TW suggests that tube position closer to the iris surface may increase the SDA even though this outcome does not influence the postoperative IOP value.
Keywords: cornea: endothelium • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • anterior chamber