Comparing the Baerveldt and Paul Glaucoma Drainage Devices and Their Effects on the Corneal Endothelium

Comparing the Baerveldt and Paul Glaucoma Drainage Devices and Their Effects on the Corneal Endothelium

Comparing the Baerveldt and Paul Glaucoma Drainage Devices and Their Effects on the Corneal Endothelium

Rationale: The Baerveldt glaucoma drainage device (GDD) successfully reduces intraocular pressure but also involves a risk of corneal endothelial deterioration. Supposedly, the tip of a GDD tube with a thinner diameter, such as the Paul implant, will remain at a larger distance from the cornea and, thereby, cause less damage. Objective: To determine whether the Paul tube induces less damage to the corneal endothelium than the Baerveldt GDD. Study design: Randomized clinical trial. Study population: Phakic patients scheduled for surgical GDD implantation. Intervention: Either a Baerveldt or a Paul GDD implant. Main study parameters/endpoints: Endothelial cell density and tube position at 24 months. Nature and extent of the burden and risks associated with participation, benefit and group relatedness: The Paul GDD may have a less harmful effect on corneal endothelium. Otherwise, both GDDs will probably have a similar risk/benefit profile. The risks of study-related assessments are negligible, burden is low, extra time is about 5 x 1.5 h (total 7.5 h) in two years.

The glaucoma drainage device consists of a plate and a tube. During surgery the plate is positioned underneath the conjunctiva and two extraocular muscles in the upper temporal quadrant of the eye. The tube is positioned in the anterior chamber.

Prism cover test: total deviation at 30 cm; Goldmann: monocular ductions in 8 directions starting from primary position, binocular field of single vision.

Inclusion Criteria: Age > 18 years. Informed consent. Caucasian ethnicity (to facilitate comparison of results with those of earlier work). Ethnicity will be based on self-reported origin of subject and/or parents. Primary open-angle glaucoma, pseudoexfoliative glaucoma, or pigmentary glaucoma. Exclusion Criteria: History of intraocular surgery (e.g. vitrectomy, cataract surgery, cyclodestructive procedures etc). History of ocular comorbidity (e.g. active uveitis, proliferative diabetic retinopathy). Pseudophakia. Functionally monocular patients. Need for glaucoma surgery combined with other ocular procedures (i.e. cataract surgery, keratoplasty, or retinal surgery) or an anticipated need for additional ocular surgery. Narrow anterior chamber angle. Best corrected visual acuity less than 0.1. Severe blepharitis.