Abstract
Purpose:
To compare immediate post operative entry site leak and hypotony rates of using two different size needles (23 and 25 gauge) in the formation of a track for insertion of a Baerveldt tube into the anterior chamber.
Methods:
Retrospective case note review of 58 patients who had Baerveldt tube implants in 2 tertiary glaucoma units. There were 2 groups being compared. Group 23G had 29 patients that were part of the primary tube versus trabeculectomy (PTVT) study and used the 23 gauge needle to form the track before insertion of the tube. The second group, 25G group, had 27 patients which were routine tube implant patients, where the surgeon’s preference of a 25 gauge needle was used. Visual acuity (VA), intraocular pressure (IOP), post operative complications and number of IOP drops were recorded at 1 day, 1 week, 1 month and 3 months after surgery.
Results:
Four patients (14%, P<0.001) in the 23G group had hypotony within the first week, compared with none in the 25G group. Two of these four eyes, in the 23G group, had anterior bleb formation and leaking from around the tube entry site, one other eye had shallowing of the anterior chamber with no anterior bleb or leak and the fourth eye had no sequelae from the hypotony. One eye in the 25G group had a shallowing of the anterior chamber at 1 week, but maintained the IOP at 9mmHg, with no leak or anterior bleb seen. There was also an additional hypotony in the 25G group at 3 months, after removal of the supramid stent. The mean IOP in the 23G group was lower than the 25G group at all time points. In the 23G group, the mean IOP was 21.5mmHg at pre-op, 16.9mmHg at day 1, 15mmHg at week 1, 17.7mmHg at month 1 and 18.5mmHg at month 3. The mean IOP in the 25G group was lower, with 26.4mmHg pre-operatively (P=0.002), 23.3mmHg at day 1 (P=0.004), 20.9mmHg at week 1 (P=0.008), 18.3mmHg at month 1 (P=0.744), and 17.1mmHg at month 3 (P=0.337).
Conclusions:
The wider 23 gauge needle track, for Baerveldt tube entry, results in lower mean IOP within the first week, although at 1 and 3 months post operatively, the IOP difference is no longer statistically significant. However, this is also at the expense of a higher hypotony rate, entry site leak and shallow anterior chamber.
Keywords: 568 intraocular pressure •
427 aqueous •
765 wound healing