Aqueous Shunt Exposure
Aqueous Shunt Exposure
Forty-three eyes from 43 patients were included in this study. Ten patients were black (23.3%), 21 were Hispanic (48.8%), 12 were white (27.9%), and 28 were women (65.1%). The average age [mean (SD)] was 64.5 years (16.4 y) and ranged from 3 to 92 years. Fourteen patients had diabetes mellitus (32.6%) and 9 (20.9%) had a family history of glaucoma. Table 1 summarizes preoperative characteristics before undergoing initial aqueous shunt implantation.
The majority of the initial surgeries were Baerveldt shunts placed in the anterior chamber and used patch grafts made of sclera. General characteristics of the initial implantations are outlined in Table 2. One intraoperative complication (scleral perforation) was reported from the initial surgeries. In another patient, a chronic preexisting retinal detachment, which was fixed and unrepairable, led to a switch from pars plana to anterior chamber tube placement.
Exposures occurred most frequently over the tube. From implantation to the initial erosion, the mean (SD) time before initial exposure was 21.5 months (28.4 mo) with a range of 0 to 118 months. Most repairs were performed in the operating room using scleral patch grafts. Details of the first exposure and subsequent repair are outlined in Table 3. One revision was complicated by retrobulbar hemorrhage. There were no other intraoperative complications documented.
Forty eyes returned for follow-up after the first exposure repair. The 3 of 43 eyes that did not contribute to follow-up data suffered from tube exposures that were treated with aqueous shunt removal. The mean (SD) duration of follow-up was 46.6 weeks (40.2 wk) with a range of 3 to 168 weeks. Thirty-five eyes had at least 4 weeks follow-up from the initial revision. Five eyes ultimately had their shunts removed at 3, 8, 50, 52, and 56 weeks postinitial revision. Twenty eyes had at least 1 year of follow-up visits with the shunt still in place. IOP, number of medications, and visual acuity remained stable during follow-up after revision (Table 4).
During the follow-up period after the first exposure repair, 3 eyes completely lost light perception (7%), all of which had neovascular glaucoma. Seventeen (43%) eyes required further intervention. The mean (SD) time required until another intervention was 78 months (13.1 mo). Complications after the first repair are listed in Table 5.
The eye suffering from patch graft exposure and the eye with elbow exposure suffered from none of the complications listed in Table 5. One eye underwent a paracentesis and later cauterization for unresolving hyphema. Another eye required paracentesis to relieve elevated IOP. One eye had multiple tube manipulations with a 30-gauge needle with an eventual aqueous shunt revision. A different eye received a new corneal patch graft, followed by the addition of another corneal patch graft with tarshorrhaphy at a later point in time. Five patients (13%) needed eventual removal of their shunt. The Kaplan-Meier survival curve for probability of not requiring revision/removal of the aqueous shunt and at least retaining light perception is displayed in Figure 1. The mean duration of being free of revision or removal was 78 weeks (13 wk), and the median duration before revision or removal was 56 weeks.
(Enlarge Image)
Figure 1.
Proportion successful (not requiring additional intervention) after first revision of aqueous shunt exposure. Marks indicate time of last follow-up without additional interventions. The mean duration of being free of revision or removal was 78 weeks (13 wk), and the median duration before revision or removal was 56 weeks.
Using a stepwise Cox regression model, the risk factor associated with time to reintervention was diabetes mellitus. Diabetes mellitus patients experienced nearly 3 times [odds ratio (OR)=2.94, P=0.028] higher the risk of failing the revision than nondiabetes patients.
Using Poisson regression with backward elimination, the number of additional interventions required after a first revision was highly associated with black race (OR=4.4, P<0.0001), number of preshunt glaucoma medications (OR=1.5 per each additional medication, P=0.0085), previous glaucoma laser surgery (OR=2.5, P=0.0081), and combined initial shunt implant surgery (OR=2.3, P=0.0289).
Results
Demographics and Preoperative Characteristics
Forty-three eyes from 43 patients were included in this study. Ten patients were black (23.3%), 21 were Hispanic (48.8%), 12 were white (27.9%), and 28 were women (65.1%). The average age [mean (SD)] was 64.5 years (16.4 y) and ranged from 3 to 92 years. Fourteen patients had diabetes mellitus (32.6%) and 9 (20.9%) had a family history of glaucoma. Table 1 summarizes preoperative characteristics before undergoing initial aqueous shunt implantation.
Initial Aqueous Shunt Implantation
The majority of the initial surgeries were Baerveldt shunts placed in the anterior chamber and used patch grafts made of sclera. General characteristics of the initial implantations are outlined in Table 2. One intraoperative complication (scleral perforation) was reported from the initial surgeries. In another patient, a chronic preexisting retinal detachment, which was fixed and unrepairable, led to a switch from pars plana to anterior chamber tube placement.
First Exposure and Repair
Exposures occurred most frequently over the tube. From implantation to the initial erosion, the mean (SD) time before initial exposure was 21.5 months (28.4 mo) with a range of 0 to 118 months. Most repairs were performed in the operating room using scleral patch grafts. Details of the first exposure and subsequent repair are outlined in Table 3. One revision was complicated by retrobulbar hemorrhage. There were no other intraoperative complications documented.
Follow-up After First Exposure Repair
Forty eyes returned for follow-up after the first exposure repair. The 3 of 43 eyes that did not contribute to follow-up data suffered from tube exposures that were treated with aqueous shunt removal. The mean (SD) duration of follow-up was 46.6 weeks (40.2 wk) with a range of 3 to 168 weeks. Thirty-five eyes had at least 4 weeks follow-up from the initial revision. Five eyes ultimately had their shunts removed at 3, 8, 50, 52, and 56 weeks postinitial revision. Twenty eyes had at least 1 year of follow-up visits with the shunt still in place. IOP, number of medications, and visual acuity remained stable during follow-up after revision (Table 4).
Complications and Additional Interventions
During the follow-up period after the first exposure repair, 3 eyes completely lost light perception (7%), all of which had neovascular glaucoma. Seventeen (43%) eyes required further intervention. The mean (SD) time required until another intervention was 78 months (13.1 mo). Complications after the first repair are listed in Table 5.
The eye suffering from patch graft exposure and the eye with elbow exposure suffered from none of the complications listed in Table 5. One eye underwent a paracentesis and later cauterization for unresolving hyphema. Another eye required paracentesis to relieve elevated IOP. One eye had multiple tube manipulations with a 30-gauge needle with an eventual aqueous shunt revision. A different eye received a new corneal patch graft, followed by the addition of another corneal patch graft with tarshorrhaphy at a later point in time. Five patients (13%) needed eventual removal of their shunt. The Kaplan-Meier survival curve for probability of not requiring revision/removal of the aqueous shunt and at least retaining light perception is displayed in Figure 1. The mean duration of being free of revision or removal was 78 weeks (13 wk), and the median duration before revision or removal was 56 weeks.
(Enlarge Image)
Figure 1.
Proportion successful (not requiring additional intervention) after first revision of aqueous shunt exposure. Marks indicate time of last follow-up without additional interventions. The mean duration of being free of revision or removal was 78 weeks (13 wk), and the median duration before revision or removal was 56 weeks.
Potential Risk Factors
Using a stepwise Cox regression model, the risk factor associated with time to reintervention was diabetes mellitus. Diabetes mellitus patients experienced nearly 3 times [odds ratio (OR)=2.94, P=0.028] higher the risk of failing the revision than nondiabetes patients.
Using Poisson regression with backward elimination, the number of additional interventions required after a first revision was highly associated with black race (OR=4.4, P<0.0001), number of preshunt glaucoma medications (OR=1.5 per each additional medication, P=0.0085), previous glaucoma laser surgery (OR=2.5, P=0.0081), and combined initial shunt implant surgery (OR=2.3, P=0.0289).
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