Abstract
Purpose: :
To determine the incidence and characteristics of the hypertensive phase following tube shunt surgeries.
Methods: :
A retrospective review of all Ahmed and Baerveldt tube shunts by a single surgeon from January 2008 to October 2011 was performed. The Ahmed valves were primed with balanced salt solution to ensure their functionality. The Baerveldt tube shunts had a 3-0 supramid suture placed within the tube lumen and were ligated with a 7-0 vicryl suture. Patients were excluded due to poor followup, intraocular pressure (IOP) measurements other than Goldmann tonometry, obvious tube occlusion (blood, fibrin, vitreous, iris), combination surgeries, or if a concomitant orphan trabeculectomy or trabeculectomy revision was performed. The hypertensive phase was defined by the following criteria: (1) IOP less than ≤ 21 mm Hg during the first 2 weeks post-operatively, and (2) 20% increase in IOP during the 3 months following surgery with IOP > 21 mm Hg. Outcome measures were the hypertensive phase incidence and IOP in the 3 months following surgery.
Results: :
One hundred and three patients were included in the study. Those with a hypertensive phase had higher pre-operative IOP compared to those who did not have a hypertensive phase (39.7 mm Hg vs. 33.6 mm Hg, p < 0.05). Hypertensive phase patients had higher IOP 1 day, 1 week, 1 month, 2 months, and 3 months after surgery (p < 0.05).There was no statistical difference in the hypertensive phase incidence between the Ahmed FP7 (31.4%), Ahmed S-2 (19.0%), and the Baerveldt (31.6%) tube shunts. Among hypertensive phase patients, there was no statistical difference in pre-operative IOP among the various shunts. The average IOP spike reached 30.7 mm Hg for the Ahmed FP7, 34.3 mm Hg for the Ahmed S-2, and 24.7 mm Hg for the Baerveldt (p < 0.05). In hypertensive phase patients, those with Baerveldt tube shunts had lower 3 month IOP compared to those with Ahmed tube shunts (Ahmed FP7 26.6 mm Hg, Ahmed S-2 30.4 mm Hg, Baerveldt 18.0 mm Hg, p < 0.05).
Conclusions: :
Elevated pre-operative IOP may be a risk factor for hypertensive phases. There was no difference in hypertensive phase incidence among the tube shunts. While hypertensive phase patients had similar pre-operative IOP among the shunts, those with Baerveldt tube shunts had less severe IOP spikes and lower IOP after 3 months.
Keywords: intraocular pressure