JJ Lee, et al. AHMED VALVE WITH TUBE LIGATION AND STENTS mmHg on the first postoperative day. Hypotony with an IOP of <6 mmHg was seen in 2 eyes (2.1%) at 1 week. All eyes had an IOP of ≥6 mmHg at 2 weeks postoperatively. An inadequate IOP decrease (IOP>21 mmHg) was detected in 25 eyes (26.3%) on the first postoperative day with a mean IOP in these eyes of 34.9 mmHg. Stent removal was performed in 16 eyes (16.8%) on the first day, in 5 eyes (5.3%) at 1 week, and 4 eyes thereafter. IOP-lowering drugs were added for 9 eyes (9.5%) after stent removal. IOP was controlled with medication only in 2 eyes (2.1%), and 2 eyes (2.1%) showed a normal IOP spontaneously at 1 week postoperatively. IOP on the visit after stent removal was in the normal range, except in one eye. No wound leakage was observed after stent removal. A record of IOP change before and 1 hour after stent removal was available for 17 eyes. Twelve eyes underwent stent removal on the first postoperative day, with a mean IOP before and 1 hour after stent removal of 42.0±7.9 mmHg and 14.1±7.6 mmHg, respectively, and this IOP reduction after stent removal was statistically significant (Wilcoxon signed rank test, p=0.002). At 1 week, the mean IOP decreased from 34.8±8.9 mmHg to 21.8±12.4 mmHg at 1 hour after stent removal (in 5 eyes), with borderline significance (p=0.068) (Table 3). The three strands of the external stents were removed en bloc in most cases for rapid IOP control. Serial stent removal was done in only two eyes. At first, one strand was removed on postoperative day one, and the IOP was measured 30 minutes after removal. The IOP was reduced from 45 mmHg to 39 mmHg in one eye and from 29 mmHg to 25 mmHg in the other eye. Due to an insufficient IOP decrease, additional stent removal was continued promptly. The IOP finally decreased to 7 mmHg (45→39→7) and 12 mmHg (29→25→12), respectively, after complete stent removal. The HP was observed in 49 eyes (51.6%) based on the Fig. 3. Mean numbers of anti-glaucoma medications (mean± standard deviation) after Ahmed glaucoma valve implantation. Paired t tests were conducted to compare the mean number of medi- cations administered at different time points. Table 2). The reduction in IOP over the first 12 months of follow-up was statistically significant (p<0.001). T tests for paired data showed a significant IOP reduction from the preoperative baseline at 1 day postoperatively (p<0.001), a significant increase from 1 week to 2 weeks PO (p<0.001), and from 1 week to 1 month postoperatively (p<0.001). A significant decrease also occurred between 1 and 2 months postoperatively (p<0.001). The mean number of anti-glaucoma medications also significantly reduced during the initial postoperative phase and then gradually increased during the first postoperative year (Fig. 3, Table 2). The mean number of anti-glaucoma medications was 3.2 preoperatively, 0.6 at 1 week, 1.0 at 2 weeks, 1.5 at 1 month, and 1.4 at 1 year postoperatively. Hypotony with an IOP of <6 mmHg was seen in 8 eyes (8.4%) and an IOP of <5 mmHg was seen in 3 eyes (3.2%) on the first postoperative day before stent removal. The mean IOP of hypotonic eyes with an IOP of <6 mmHg was 4.1 Table 3. Comparisons of IOPs before and after stent removal Time of stent removal Mean IOP before removal Mean IOP 1 hour after removal First day (12 eyes) 42.0±7.9 mmHg 14.1±7.6 mmHg First week (5 eyes) 34.8±8.9 mmHg 21.8±12.4 mmHg * Wilcoxon signed rank test was conducted to compare mean IOPs before and after stent removal. p value* 0.002 0.068 Table 4. Postoperative complications Complications Hypotony Shallow anterior chamber Hyphema Tube occlusion Choroidal effusion Phthisis bulbi Exotropia Exposure of plate Bullous keratopathy Corneal opacity (site of tube touch) Early (before 3 months) No. of eyes (%) 8 (8.4%) 6 (6.3%) 17 (17.9%) 2 (2.1%) 1 (1.0%) 0 0 0 0 0 Late (after 3 months) No. of eyes (%) 2 (2.1%) 0 0 0 0 3 (3.2%) 1 (1.0%) 1 (1.0%) 1 (1.0%) 1 (1.0%) 89