Graft-free Ahmed tube insertion: a modified method at 5 mm from limbus

Five-Year Outcomes of Graft-Free Tube Shunts and Risk Factors for Tube Exposures in Glaucoma

PRCIS

Use of a scleral tunnel technique instead of a patch graft can be considered in most cases of tube shunt implantation. Grafts may still be considered in younger (<65 y old) East Asians.

PURPOSE

(1) To assess the risk factors for tube exposure with a graft-free implantation technique and (2) to examine 5-year outcomes of graft-free tube shunt insertion.

METHODS

This was a retrospective case series of 204 consecutive eyes undergoing a glaucoma tube shunt implantation with a scleral tunnel technique in lieu of a graft. Preoperative and postoperative best-corrected visual acuity, intraocular pressure, and number of glaucoma medications were compared. Failure was defined as the following: (1) intraocular pressure >21 mm Hg or ≤5 mm Hg on 2 consecutive visits after 3 mo; (2) required additional glaucoma surgery; (3) loss of light perception. Univariable and multivariable regression analyses were conducted to identify risk factors of tube exposures.

RESULTS

Intraocular pressure and the number of glaucoma medications were significantly decreased at all postoperative time points ( P <0.001). Success rates were 91% at year 1, 75% at year 3, and 67% at year 5. The most common early (<3 mo) complication was tube malpositioning. The most common late (>3 mo to 5 y) complications were corneal complications and uncontrolled intraocular pressure. By year 5, 6.9% of tubes were exposed. Multivariable regression showed that age less than 65 years old (odds ratio: 3.66, P =0.04) and East Asian ethnicity (odds ratio: 3.36, P =0.04) were associated with significantly increased risk of tube exposure.

CONCLUSIONS

Graft-free glaucoma tube implantation has comparable long-term outcomes and complication rates to shunts with a graft. Younger (<65 y old) East Asians are at greater risk of tube exposure without a graft.

Ahmed Glaucoma Valve Implantation to Reduce Intraocular Pressure: Updated Perspectives

Trabeculectomy and glaucoma drainage device implantation are the most commonly performed glaucoma surgeries worldwide. Although trabeculectomy is the gold standard, at the present time there is an increase in the use of glaucoma drainage devices. The Ahmed glaucoma valve is one of the most widely used glaucoma drainage devices worldwide. Corneal endothelial cell loss and eventually corneal decompensation is one of the serious complication of glaucoma drainage device implantation. To avoid this, drainage tube can be inserted into the ciliary sulcus instead of the anterior chamber, especially in eyes with high risk for corneal decompensation. Tube/plate exposure, hypertensive phase, endophthalmitis, cataract formation, diplopia and ocular hypotony are the other potential complications that can develop after Ahmed glaucoma valve implantation.

Autologous Scleral Pocket Technique for Ahmed Glaucoma Valve Implantation with Pars Plana Tube Insertion for Neovascular Glaucoma

Specific postoperative complications, such as tube exposure and conjunctival erosion, have occurred despite the favorable surgical outcomes of tube shunt surgeries for refractory glaucoma. The new autologous scleral pocket technique is performed by inserting the tube into the vitreous cavity without using a donor scleral patch. The purpose of this study was to evaluate the surgical results of Ahmed glaucoma valve (AGV) implantation using this technique for neovascular glaucoma (NVG), which is one of the representative refractory types of glaucoma. This observational retrospective case series included 15 consecutive eyes of 15 patients with NVG who had undergone AGV implantation at Kobe University between January 2018 and December 2019. The mean preoperative intraocular pressure (IOP) was 37.2 ± 13.8 mmHg and the glaucoma drug score was 4.2 ± 2.2. The mean IOP and glaucoma drug score at 1 year postoperatively decreased to 15.0 ± 4.6 mmHg and 1.3 ± 2.0, respectively (p < 0.001). No significant change in the corneal endothelial cell density following surgery was observed (p = 0.09); however, one patient required an additional trabeculectomy at 7 months postoperatively. No cases of tube exposure or conjunctival erosion were observed at 1 year postoperatively. These results indicated the effectiveness and safety of this technique in patients with NVG.

Ahmed Glaucoma Valve Implantation: Graft-Free Short Tunnel Small Flap versus Scleral Patch Graft after 1-Year Follow-up: A Randomized Clinical Trial

PURPOSE

To compare the efficacy and safety of the graft-free short tunnel small flap (STSF) technique with that of the scleral patch graft (SPG) in Ahmed glaucoma valve (AGV) (New World Medical Inc, Rancho Cucamonga, CA) implantation.

DESIGN

Randomized clinical trial.

PARTICIPANTS

A total of 203 eyes of 203 patients with medically uncontrolled glaucoma, including 102 in the STSF group and 101 in the SPG group.

METHODS

Patients were enrolled and assigned randomly to STSF or SPG.

MAIN OUTCOME MEASURES

Tube exposure, intraocular pressure (IOP), number of glaucoma medications, best-corrected visual acuity, surgical complications, and success rate (defined as IOP >5 mmHg, ≤21 mmHg, and IOP reduction ≥20% from baseline at 2 consecutive visits after 3 months, no reoperation for glaucoma).

RESULTS

Only 1 patient in the SPG group developed tube exposure at 1-year follow-up. The cumulative probability of success during the first year of follow-up was 70% in the STSF group and 65% in the SPG group (P = 0.36). The IOP decreased significantly from 29.6±8.6 mmHg at baseline to 16.4±3.6 mmHg at the final follow-up in the STSF group (P = 0.001). The corresponding numbers for the SPG group were 30.9±11.2 and 15.8±4.7, respectively (P = 0.001). The final IOP was comparable between both groups (P = 0.65). Mean ± standard deviation of the number of glaucoma medications was 1.8±0.9 in the STSF group and 1.6±0.9 in the SPG group at final follow-up (P = 0.32). Postoperative complications developed in 8 patients (19%) in the STSF group and 9 patients (23%) in the SPG group (P = 0.81).

CONCLUSIONS

The STSF and SPG techniques had a comparable complication rate at the 1-year follow-up. Both techniques were comparable in terms of success rate, postoperative IOP, and glaucoma medications.

Graft-free glaucoma drainage device implantation: Short tunnel small flap technique

PURPOSE:

To introduce a new technique of short tunnel small flap graft-free glaucoma drainage device implantation and report our early experience.

METHODS:

In a retrospective study, patients with uncontrolled primary open-angle glaucoma underwent short tunnel small flap graft-free Ahmed glaucoma valve implantation. In this technique, plate is sutured 8-10 mm posterior to the limbus and a partial thickness flap is made at 1 or 11 o'clock position, 1 mm posterior the limbus. Tube was passed through a tunnel immediately anterior to the plate into the proximal edge of the flap and then inserted into the anterior chamber via a route underneath the flap. Flap then covered the distal end of the tube and conjunctiva was sutured. Patients were followed for a minimum of 12 months for any sign of tube exposure and rise of intraocular pressure.

RESULTS:

A total of 16 consecutive patients with refractory primary open-angle glaucoma and uncontrolled intraocular pressure were included in this study. Mean age of participants was 59 ± 8.3 years and nine (56%) were male. Mean intraocular pressure at the time of presentation was 26 ± 6.2 mm Hg, which dropped to 16 ± 4.5 at 12 months postoperative follow-up. The number of medications at baseline was 3 ± 1 eye drops, which was decreased to 1 ± 1.2 at 12 months. There were no conjunctival and flap-related complications or any sign of tube exposure during 1-year postoperative period.

CONCLUSION:

Short tunnel small flap graft-free glaucoma drainage device implantation technique combines advantages of both tunneling and flap techniques. Also, it may result in better tube positioning and more favorable cosmetic outcomes.