Korean J Ophthalmol.  2009 Jun;23(2):86-92. 10.3341/kjo.2009.23.2.86.

Clinical Outcomes of Ahmed Glaucoma Valve Implantation Using Tube Ligation and Removable External Stents

• Lee JJ
• Park KH
• Kim DM
• Kim TW

• KMID: 754723
• DOI: http://doi.org/10.3341/kjo.2009.23.2.86

Abstract

PURPOSE: To investigate the immediate and long-term outcomes of Ahmed glaucoma valve (AGV) implantation with silicone tube ligation and removable external stents.
METHODS
This retrospective non-comparative study investigated the outcomes of AGV implantation with silicone tube ligation and removable external stents in 95 eyes (90 patients) with at least 12 months of postoperative follow-up. Qualified success was defined as an intraocular pressure (IOP) of < or =21 mmHg and > or =6 mmHg regardless of anti-glaucoma medication. Those who required additional glaucoma surgery, implant removal or who had phthisis bulbi were considered failures. Hypotony was defined as an IOP of <6 mmHg.
RESULTS
Mean IOP reduced from 37.1+/-9.7 mmHg preoperatively to 15.2+/-5.6 mmHg at 12 months postoperatively (p<0.001). Qualified success was achieved in 84.2% at 1 year. Hypotony with an IOP of <6 mmHg was seen in 8.4% and an IOP of <5 mmHg in 3.2% on the first postoperative day. No case of hypotony required surgical intervention. Suprachoroidal hemorrhage did not occur in this study. When stents were removed on the first postoperative day because of an insufficient IOP decrease, the mean IOP decreased significantly from 42.0 mmHg to 14.1 mmHg (p<0.001) after 1 hour. The most common complication was hyphema, which occurred in 17.9%.
CONCLUSIONS
Hypotony-related early complications requiring surgical intervention were reduced by ligation and external stents in the tube. In addition, early postoperative high IOPs were managed by removing external stents. The described method can prevent postoperative hypotony after AGV implantation and showed long-term success rates comparable to those reported previously.

Keyword

Ahmed glaucoma valve; External stents; Tube ligation

MeSH Terms

Equipment Design
Female
Filtering Surgery/*instrumentation
Follow-Up Studies
Glaucoma/physiopathology/*surgery
*Glaucoma Drainage Implants
Humans
Intraocular Pressure
Ligation/instrumentation
Male
Middle Aged
Retrospective Studies
*Silicone Elastomers
*Stents
Time Factors
Treatment Outcome

Figure

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  Fig. 1 Ahmed glaucoma valve implant surgery with ligation of silicone tube and external stents. (A) A limbus-based scleral flap was created with a Beaver knife. (B) The AGV plate was placed in the sub-Tenon's space in the supero-temporal quadrant. (C) The silicone tube and 3 strands of 8-0 Nylon were ligated with 8-0 Vicryl, and the ligature was tightened until the internal lumen of the tube collapsed. (D) The lengths of the exposed 8-0 Nylon strands were kept to about 5 mm to minimize corneal irritation.

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  Fig. 2 The mean intraocular pressure (mean±standard deviation) after Ahmed glaucoma valve implantation. The hypertensive phase occurred between 2 weeks and 1 month postoperatively. Paired t tests were used to compare the mean intraocular pressures at different time points.

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  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 medications administered at different time points.

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  Fig. 4 Cumulative probability of success over time, based on Kaplan Meier survival analysis. Cumulative probability at 12 months was 84.2%.

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