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ASCRS ♦ ASOA Symposium & Congress
Technicians & Nurses Program
May 6-10, 2016 – New Orleans
THE ROLE OF ISTENT IN MANAGING GLAUCOMA
David H. Park, M.D.
HUMAN COST OF GLAUCOMA
Glaucoma is the second leading cause of blindness globally
Glaucoma estimated to increase from 60 million in 2010 to 78 million by
2020 worldwide. In the US, cases estimated to reach 3 million by 20201.
Bilateral blindness in 7.5% of glaucoma cases (6 million by 2020
worldwide2, 88,000 in the US3).
1. Quigley HA. Number of people with glaucoma worldwide. Br J Ophthalmol. 2006 March; 90(3): 262–267. 2. Congdon NG, De Jong PT, Klein BE et al.Glaucoma as a cause of blindness in the US. American Glaucoma Society 2003; Abstract. 3. Friedman DS, De Jong PT, Klein BE, et al. Glaucoma prevalence in the United States: results of a meta-analysis. American Glaucoma Society Annual Meeting 2003; Abstract.
CONCOMITANT GLAUCOMA IN CATARACT PATIENTS (U.S.)
Approximately 3.5 million cataract surgeries performed annually in the U.S.
Approximately 1 in 5 cataract patients have concomitant glaucoma.
Centers for Medicare and Medicaid Services. 2002 – 2007. Medicare Standard Analytical File. Baltimore, MD. 2007 .
THE ISTENT TRABECULAR MICRO-BYPASS STENT SYSTEM
WHAT IS IT? First available ab-interno TM micro-bypass system for glaucoma made of titanium
WHAT DOES IT DO? Improves aqueous outflow through the natural physiologic pathway
INDICATIONS: For use in conjunction with cataract surgery for reduction of IOP in adult patients with mild to moderate glaucoma on ocular hypotensive medication
ADVANTAGES OF ISTENT
Lowers IOP while reducing medication burden
Decreases the risk of IOP fluctuation from non-compliance with medication
Spares the conjunctiva to preserve future treatment options
Avoids serious complications with filtration or shunt procedures such as hypotony or bleb related complications
GLAUCOMA STAGING
Mild Stage Glaucoma
Optic nerve abnormalities consistent with glaucoma, but no visual field abnormalities (may show defects on SW or frequency doubling perimetry)
Moderate Stage Glaucoma
Visual field abnormalities in one hemifield, not within 5 degrees of fixation
Severe Stage Glaucoma
Visual field abnormalities in two hemifields, or within 5 degrees of fixation in at least one hemifield
ISTENT INJECTOR SYSTEM
Sterile, pre-loaded, disposable
Re-acquisition capability due to ‘grasping claws’
Open Half Pipe 1 mm
Self-Trephining Tip
Snorkel
0.3 mm
Retention Arches
Lumen 120 µm
AQUEOUS OUTFLOW ANATOMY
ANATOMIC PLACEMENT AND RATIONALE
Designed to improve continuous, physiologic outflow
Ideal placement is in the inferonasal location where there is a higher density of collector channels
Preservation of the TM ensures a natural episcleral back-pressure of 8 - 11 mmHg which limits the risk of hypotony.4
4. Rosenquist R, Epstein D, Melamed S, et al. Outflow resistance of enucleated human eyes at two different perfusion pressures and
different extents of trabeculotomy. Curr Eye Res 1989;8:1233-40
ISTENT SURGICAL PLACEMENT
iStent rails are seated against the wall of Schlemm’s canal
iStent snorkel sits parallel to the iris plane
ISTENT US INVESTIGATIONAL DEVICE EXEMPTION TRIAL
Prospective, randomized, multi-centered study of POAG patients who underwent iStent + cataract surgery vs. cataract surgery alone
290 subject at 29 sites
240 randomized subjects with concomitant cataract and mild-to-moderate POAG (including PXF and PDS), IOP ≤ 24 mmHg on 1-3 medications with IOP range of 22-36 following washout
Efficacy endpoints:
IOP ≤ 21 mmHg without meds at month 12
IOP reduction ≥ 20% without meds at month 12
Follow-up 2 years post-op
PRIMARY EFFICACY OUTCOME
18% more patients with cataract surgery plus iStent achieved IOP of ≤ 21 mmHg with no medications
iStent + CataractCataract
p = .004
% e
yes
Primary Endpoint ≤ 21 mm Hg IOP with no medications at month 12
68%
50%
SECONDARY EFFICACY OUTCOME
17% more patients with cataract surgery plus iStent achieved ≥20% reduction in IOP with no medications
iStent + CataractCataract
Secondary Endpoint ≥ 20% IOP reduction with no medications at month 12
p = .010
64%
47%
% e
yes
SIGNIFICANT IOP AND MEDICATION REDUCTION
For iStent subjects, after 12 months:
30% reduction from baseline IOP
IOP reduction below 21 mmHg with significantly (p = 0.001) less medication*
35% vs 15% (iStent) on medication
*Samuelson TW, Katz LJ, Wells JM, et al. Randomized evaluation of the trabecular micro-bypass stent with
phacoemulsification in patients with glaucoma and cataract. Ophthalmology. 2011;118:459-467 .
SAFETY PROFILE
Reported Adverse Events
iStent® + cataract surgery N=116 n(%)
Cataract surgery only N=117 n(%)
Early postoperative corneal edema 9 (8%) 11 (9%)
Any BCVA loss of at least one line at or after the 3 month visit 8 (7%) 12 (10%)
Posterior capsular opacification 7 (6%) 12 (10%)
Stent obstruction 5 (4%) NA
Blurry vision or visual disturbance 4 (3%) 8 (7%)
Elevated IOP 4 (3%) 5 (4%)
Excerpts from complete listing of safety population
Comparable safety profile to cataract surgery
ADDITIONAL STUDIES
2 year Follow Up to US IDE Trial5: To assess long-term safety and efficacy of a
single stent with concomitant cataract surgery vs cataract surgery alone5
The iStent group had significantly better IOP control on no medication through 24 months vs. the control group
Safety profile similar between the groups
Fea et al6 demonstrated lower IOP in the iStent group after terminal washout of meds, with magnitude of IOP reduction similar to the effect of one med
5. Craven, et al. JCRS 2012;38:1339-1345.
6. Fea AM. Phacoemulsification versus phacoemulsification with micro-bypass stent implantation in primary open-angle glaucoma. J
Cataract Refrac Surg. 2010;36:407-412.
AQUEOUS OUTFLOW ANATOMY
SUMMARY: ISTENT PLACEMENT DURING CATARACT SURGERY
Reduces IOP while reducing the number of medications or eliminating the need for medication
Decreases risk of non-compliance, especially related to IOP fluctuation from non-adherence to medication
Avoids serious complications with end-stage filtration or shunt procedures such as hypotony or bleb-related problems
Spares the conjunctiva preserving potential for future treatment options
SURGICAL PEARLS FOR ISTENT
Optimize patient head position as well as microscope angle for best visualization of the angle anatomy through gonio prism
Plan ahead to make sure primary incision is amenable for a comfortable and ideal approach during iSTENT implantation.
Use plenty of OVD to widen the angle, but not too much as over pressurizing the eye can collapse Schlemm’s canal
Have plenty of OVD on hand to ‘clear’ areas of heme when first few attempts are unsuccessful
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