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Meta-Analysis
. 2015 May 27;10(5):e0128146.
doi: 10.1371/journal.pone.0128146. eCollection 2015.

iStent as a Solo Procedure for Glaucoma Patients: A Systematic Review and Meta-Analysis

Monali S Malvankar-Mehta  1 , Yufeng Nancy Chen  2 , Yiannis Iordanous  3 , Wan Wendy Wang  2 , John Costella  4 , Cindy M L Hutnik  3
Affiliations
Meta-Analysis

iStent as a Solo Procedure for Glaucoma Patients: A Systematic Review and Meta-Analysis

Monali S Malvankar-Mehta et al. PLoS One. .

Abstract

Background: Glaucoma is a leading cause of irreversible blindness. It is firmly entrenched in the traditional treatment paradigm to start with pharmacotherapy. However, pharmacotherapy is not benign and has been well documented to have a number of significant challenges. Minimally invasive glaucoma surgery (MIGS) that targets the outflow pathway with minimal to no scleral dissection has resulted in the need to reconsider the glaucoma treatment paradigm.

Purpose: To perform a systematic review and meta-analysis to evaluate and quantify the effect on post-operative intraocular pressure (IOP) and number of topical glaucoma medications, in patients receiving the iStent MIGS device as the solo procedure without concurrent cataract surgery.

Methods: A systematic review was conducted by searching various databases between January 1, 2000, and June 30, 2014. Studies reporting up to a maximum follow-up period of 24 months were retrieved and screened using the EPPI-Reviewer 4 gateway. Percentage reduction in IOP (IOPR%), and mean reduction in topical glaucoma medications after surgery were computed. Meta-analysis was performed using STATA v. 13.0. The standardized mean difference (SMD) was calculated as the effect size for continuous scale outcomes. Heterogeneity was determined using the I2 statistics, Z-value, and χ2 statistics. Fixed-effect and random-effect models were developed based on heterogeneity. Sub-group analysis was performed based on the number of iStents implanted and the follow-up period. The outcome measures were changes in the IOP and number of glaucoma medications.

Results: The search strategy identified 105 records from published literature and 9 records from the grey literature. Five studies with 248 subjects were included for quantitative synthesis. A 22% IOP reduction (IOPR%) from baseline occurred at 18-months after one iStent implant, 30% at 6-months after two iStents implantations, and 40% at 6-months after implantation of three iStents. A mean reduction of 1.2 bottles per patient of topical glaucoma medications occurred at 18-months after one iStent implant, 1.45 bottles per patient at 6-months after two iStents, and one bottle of medication per patient was reduced at 6-months following placement of three iStents implants. Meta-analysis results showed a significant reduction in the IOP after one iStent (SMD = -1.68, 95% CI: [-2.7, -0.61]), two iStents (SMD = -1.88, 95% CI: [-2.2, -1.56]), and three iStents (SMD = -2, 95% CI: [-2.62, -1.38]) implantation. Results showed a significant drop in the topical glaucoma medications after one iStent (SMD = -2.11, CI: [-3.95, -0.27]), two iStent (SMD = -1.88, CI: [-2.20, -1.56]), and three iStents (SMD = -2.00, CI: [-2.62, -1.38]) implantation. The maximum reduction in IOP occurred at 12-months (SMD = -2.21, CI: [-2.53, -1.88]) and a significant reduction in post-operative topical glaucoma medications occurred even after 18-months of iStent implantation (SMD = -0.71, CI: [-1.15, -0.26]).

Conclusion: iStent implantation as a solo procedure without concurrent cataract extraction does lower IOP, and reduces the dependency on glaucoma medications. This effect seems to last at least 18 months.

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Conflict of interest statement

Competing Interests: The authors have declared that no competing interests exist.

Figures

Fig 1
Fig 1. PRISMA Flow Diagram for iStent as a Solo Procedure for Patients with Glaucoma.
Fig 2
Fig 2. Funnel plot for studies examining pre- and post-operative intraocular pressure (IOP) by follow-up (months).
Fig 3
Fig 3. Funnel plot for studies examining pre- and post-operative IOP by number of iStents inserted.
Fig 4
Fig 4. Funnel plot for studies examining pre- and post-operative number of medications by follow-up (months).
Fig 5
Fig 5. Funnel plot for studies examining pre- and post-operative number of medications by number of iStents inserted.
Fig 6
Fig 6. Forest plot for pre- and post-operative IOP by number of iStents inserted.
Fig 7
Fig 7. Forest plot for pre- and post-operative IOP by follow-up (months).
Fig 8
Fig 8. Forest plot for pre- and post-operative number of medications by number of iStents inserted.
Fig 9
Fig 9. Forest plot for pre- and post-operative number of medications by follow-up (months).
See this image and copyright information in PMC

References

    1. International Federation on Ageing (2013) The High Cost of Low Vision: The Evidence on Ageing and the Loss of Sight Executive Summary: International Federation on Ageing.
    1. Glaucoma Research Foundation (2013) Glaucoma Facts and Stats.
    1. WHO Media Centre (2013) Visual impairment and blindness. World Health Organization.
    1. American Academy of Ophthalmology (AAO) (2011) Eye Health Statistics American Academy of Ophthalmology.
    1. The National Coalition for Vision Health (2010) Vision Loss in Canada 2011.

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