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  • Tube Shunts and Long-Term VF Outcomes

    By Lynda Seminara
    Selected By: Richard K. Parrish II, MD
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    Journal Highlights

    American Journal of Ophthalmology, August 2020

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    Until recently, glaucoma drainage devices were reserved for patients with refractory glaucoma and poor vision. Now, however, these devices are pop­ular for reducing intraocular pressure (IOP), even in patients with good vision. Previous studies of tube shunts focused on outcomes such as visual acuity, IOP, and overall surgical success. In a retrospective case series, Liu et al. looked at the visual field (VF) changes associated with these types of implants, with emphasis on global and regional VFs. During three years of follow-up, they noted that surgery and shunt implantation appeared to stabilize IOP and VF progression.

    Study participants had been fitted with one of three tube shunts (Ahmed, Baerveldt, or Molteno) during a five-year period. All patients had visual acuity that was correctable to 20/20 and evidence of worsening glaucoma or IOP that would likely start contributing to further visual damage. VF testing was performed before surgery. Shunt placement was followed by a post-op regimen of antibiotic and prednisolone eye drops.

    Data were collected for 95 patients (106 eyes) and included demographics, comorbidities, and results of glaucoma exams before surgery and annually thereafter for three years. Collabora­tive Initial Glaucoma Treatment Study (CIGTS) scores were applied to assess changes in VFs following the surgery. Regression analysis was used to deter­mine risk factors that may affect VF changes after implantation.

    Data analysis showed that shunt implantation led to decreases in IOP; the mean value dropped from 23.1 mm Hg to 12.7 mm Hg. The number of glaucoma medications needed by patients three years post-op also declined markedly. Global VF metrics (including mean deviation, pattern deviation, and CIGTS pattern deviation probability) remained stable, whereas global CIGTS total deviation probability increased mildly. The greatest risk factors for CIGTS changes were older age and higher number of pre-op glaucoma medications.

    The authors suggest that the shunts offer safe and effective IOP control but may not be as good as traditional trab­eculectomy. In their study, the Ahmed device was used more often than the others, so further work is needed to compare outcomes for the various implants.

    The original article can be found here.