Evaluation of ahmed glaucoma valve implantation through a needle-generated scleral tunnel in Mexican children with glaucoma

Abstract

Purpose:To evaluate the results and extrusion rates of the Ahmed glaucoma valve (AGV) implantation through a needle-generated scleral tunnel, without a tube-covering patch, in children.Materials and Methods:A retrospective review of the charts of 106 Mexican children implanted with 128 AGVs operated between 1994 and 2002, with the needle track technique, at our institution, with at least six months follow up was done. Main outcome measures were intraocular pressure (IOP) control, tube extrusions or exposure and other complications.Results:Kaplan-Meier analysis demonstrated a 96.9% survival rate at six months, 82.4% at one year, 78.7% at two years, 70% at three years and 41.6% at four years. Total success at the last follow-up (IOP between 6 and 21 mm Hg without medications) was achieved in 30 eyes (23.5%), 58 eyes (45.3%) had qualified success (only topical hypotensive drugs) and 40 eyes (31.3%) were failures. The mean pre- and post-operative IOP at the last follow up was 28.4 mmHg (SD 9.3) and 14.5 mmHg (SD 6.3), respectively. No tube extrusions or exposures were observed. Tube-related complications included five retractions, a lens touch and a transitory endothelial touch. The risk of failure increased if the eye had any complication or previous glaucoma surgeries.Conclusion:Medium-term IOP control in Mexican children with glaucoma can be achieved with AGV implantation using a needle-generated tunnel, without constructing a scleral flap or using a patch to cover the tube. There were no tube extrusions, nor any tube exposures with this technique.

Review on the Management of Primary Congenital Glaucoma

“…None of the patient had tube extrusion during the 6-month follow-up. 69 Although the result is not statistically significant due to the small sampling size (CI < 1.5%), the study sheds insight to the alternative methods of GDD insertion.…”

Aqueous shunt implantation in glaucoma

“…[32] An alternative long intrascleral tunnel technique without patch has been described with good midterm results. [33]…”

Achieving Target Pressures with Combined Surgery: Primary Patchless Ahmed Valve Combined with Phacoemulsification vs Primary Phacotrabeculectomy

“…On the other hand, the lack of tube extrusions and exposures is actually closer to truth, since any such complication would need a surgical procedure that would necessarily be recorded at the chart; our patchless technique has been reported to have a low rate of tube extrusions/exposure. 19 35…”

“…The surgical technique used in these cases has been described in detail elsewhere and does not involve use of a scleral patch graft. 17 - 19 In brief, a fornix-based conjunctival flap was created in the superotemporal quadrant and the Ahmed plate was sutured to the scleral bed 8 to 10 mm behind the limbus with 7-0 silk. A scleral tunnel initiated 3 to 4 mm from the limbus was constructed using a 23 G needle, bent in a ‘Z’ formation to avoid interference from the eyelids, brow or lid speculum.…”