BACKGROUND: Hypotony with shallow or flat chamber and hypertony without filtration are important short-term complications of filtering procedures in glaucoma. Both reflect the difficulty to adjust the tension of the scleral flap in a way that the artificial valve opens at pressures within the therapeutic range. Our aim was to avoid these complications by improving the filling test. PATIENTS AND METHOD: 22 eyes of 21 patients with chronic glaucoma of different etiology underwent a trabeculectomy. After preliminarily fixing the sutures, the anterior chamber was filled until fluid appeared at the rim of the scleral flap. Then, the pressure was measured using a newly developed, sterilizable applanation tonometer. By tightening or loosening the sutures the opening pressure was adjusted to values between 5 and 20 mm Hg. RESULTS: The IOP at the first postoperative day correlated well with the intraoperative flap opening pressure (correlation coefficient 0.771), but was 20% lower at the average. All cases had a sufficient filtering zone and IOP below 20 mm Hg. At the first day, all chambers were deep. After 2 to 9 days, 4 eyes developed temporarily a shallow chamber (minimum depth: 1 1/2 times corneal thickness). This complication occurred only in eyes with intraoperative pressures of 5 to 10 mm Hg. CONCLUSION: Intraoperative pressure control during trabeculectomy allows a fairly good determination of the postoperative IOP. Choosing a suitable pressure level (15 to 20 mm Hg), hypotony and shallow chambers should be avoided. Hypertony can be hindered, as well.
BACKGROUND:Hypotony with shallow or flat chamber and hypertony without filtration are important short-term complications of filtering procedures in glaucoma. Both reflect the difficulty to adjust the tension of the scleral flap in a way that the artificial valve opens at pressures within the therapeutic range. Our aim was to avoid these complications by improving the filling test. PATIENTS AND METHOD: 22 eyes of 21 patients with chronic glaucoma of different etiology underwent a trabeculectomy. After preliminarily fixing the sutures, the anterior chamber was filled until fluid appeared at the rim of the scleral flap. Then, the pressure was measured using a newly developed, sterilizable applanation tonometer. By tightening or loosening the sutures the opening pressure was adjusted to values between 5 and 20 mm Hg. RESULTS: The IOP at the first postoperative day correlated well with the intraoperative flap opening pressure (correlation coefficient 0.771), but was 20% lower at the average. All cases had a sufficient filtering zone and IOP below 20 mm Hg. At the first day, all chambers were deep. After 2 to 9 days, 4 eyes developed temporarily a shallow chamber (minimum depth: 1 1/2 times corneal thickness). This complication occurred only in eyes with intraoperative pressures of 5 to 10 mm Hg. CONCLUSION: Intraoperative pressure control during trabeculectomy allows a fairly good determination of the postoperative IOP. Choosing a suitable pressure level (15 to 20 mm Hg), hypotony and shallow chambers should be avoided. Hypertony can be hindered, as well.