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James Kim, Samantha J. Chai, Jonathan A. Eisengart, Scott D. Smith; Outcomes Following Revision of the Ahmed Glaucoma Valve. Invest. Ophthalmol. Vis. Sci. 2011;52(14):2639.
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To determine the efficacy of revision of the Ahmed Glaucoma Valve (AGV) with uncontrolled intraocular pressure (IOP) from cyst encapsulation or fibrous ingrowth.
Retrospective medical records of 28 consecutive patients (28 eyes) that underwent an AGV revision for an encapsulated cyst or fibrous ingrowth at the Cole Eye Institute from January 1, 1995 to April 10, 2010 with at least 4 months of follow-up or less if failure occurred were reviewed. The following information was recorded for each patient: age, gender, race, past ocular history, type of glaucoma, type of glaucoma implant, best corrected visual acuity (BCVA), IOP, number of glaucoma medications, presence of bleb encapsulation, presence of fibrous ingrowth, use of mitomycin C, and complications. The primary outcome measure was cumulative probability of surgical success, evaluated by Kaplan-Meier survival analysis. Failure was defined by IOP between <6mmHg or >21mmHg at 3 consecutive visits, loss of light perception, the need for additional glaucoma surgery or visually devastating complication. Secondary outcome measures were the level of IOP, number of glaucoma medications, and the occurrence of complications. Factors associated with success were also assessed by multivariate Cox proportionate hazards models.
Of the 28 eyes, 14 eyes failed within the follow-up period. The mean duration of follow-up was 24.9 ± 21.9 months. The probability of success based on Kaplan-Meier survival analysis was 78% at 1 year, 49% at 2 years, and 44% at 3 years. In comparison to the mean baseline IOP of 29.9 ± 7.6mmHg, the mean IOPs at 1 year (17.5 ± 1.0mmHg, p=<0.0005) and 2 years (19.5 ± 1.6mmHg, p=0.007) were significantly reduced. In comparison to the mean baseline number of glaucoma medications of 3.2 ± 1.0, the mean number of medications at 1 year (2.3 ± 1.2, p=.01) was significantly reduced. Medication use at 2 years (2.3 ± 1.5, p=.15) was not significantly reduced from baseline. Sex, age, race, AGV type, etiology of failure, use of mitomycin C, baseline IOP, and glaucoma subtype were not associated with the failure rate. Complications requiring additional surgery occurred in 3 (11%) eyes, with no eyes suffering a visually significant complication.
Revision of a failed AGV from an encapsulated cyst or fibrous ingrowth significantly reduces IOP in most patients, and is a reasonable option to consider as an alternative to placement of a 2nd glaucoma implant.
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