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The value of reducing medication with the iStent inject W

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iStentBy Mark Gallardo, MD

With the continuing rise of glaucoma sufferers,1 new therapies that will treat the disease without further decreasing a patient’s quality of life are always in great demand. Medications are an established, effective, and non-invasive method of treating glaucoma through the lowering of intraocular pressure (IOP). However, they are not as benign as many assume. Though they are not incisional and do not carry the risks more invasive therapies may, they still may cause significant damage. The risk of side effects and the significantly negative impact on a patient’s quality of life which may result from medications need to be considered. These drawbacks are also often exacerbated by patient compliance issues which can result in acceleration of disease and loss of visual acuity.

Data show that more than 50% of glaucoma patients have a concomitant diagnosis of dry eye disease (DED) and that DED occurs more often in patients that use higher numbers of glaucoma medications and with longer disease duration.2 While DED might not be at the forefront of a glaucoma specialist’s mind, it is a major factor in ocular health and patient quality of life and is frequently exacerbated by glaucoma treatment. Benzalkonium chloride (BAK), a common preservative in topical glaucoma medications, has been shown to have corneal and conjunctival toxicity and disrupt tear film production and stability.3-5 I frequently see glaucoma patients with an inflamed ocular surface and red eyelid margins. Additionally, prostaglandin analogs, which are the most common medications used, may cause conjunctival hyperemia and other side effects including iris and eyelid pigmentation changes and periorbital lipodystrophy.6 These can cause a deepening of the upper eyelid sulcus and give patients an appearance of ptosis, which can be permanently disfiguring and make it difficult to continue to monitor ocular pressure.

In addition to toxicity concerns, it is well established that glaucoma patients have poor compliance with topical drops and that compliance further decreases as the number of prescribed medications increases.7,8 Medications definitely serve a purpose and always will. However, the value of getting a patient off even one medication is significant, though too often undervalued when considered in outcomes assessments.

The Benefits of the iStent inject W

Microinvasive glaucoma surgeries (MIGS) have proven to be a safe and beneficial alternative to topical medications, including the most recent MIGS innovation, iStent inject W (Glaukos Corp). The dual wide-flange stent device contains two heparin-coated, titanium stents which can be inserted during a single procedure. The micro-bypass stents have a 360 mm diameter flange, a thorax that resides in the trabecular meshwork, and then a head that resides in Schlemm’s canal with 4 side flow outlets to facilitate multi-directional outflow.

The injector is inserted perpendicular to the trabecular meshwork, and with careful technique, the stents are implanted with a push of a button. Multiple stents allow for more coverage and an increased likelihood of implantation near functioning collector channels which can improve results. The safety profile on this device is excellent9-11 and insertion of the stents is straightforward and elegant with a manageable learning curve. Since the device is labeled for use in conjunction with cataract surgery, the patient is spared from an additional procedure.

Medication Reduction Possibilities

Given the tremendous burden placed on patients by medications, the potential to reduce or eliminate them should be a priority for physicians. As the iStent inject W is indicated for mild to moderate glaucoma patients, the reduction rate is often sufficient to achieve this goal in many patients. Multiple studies demonstrate 80% to 100% of eyes achieve ≥20% IOP reduction with one or no medications; overall ≥80% of eyes require fewer medications, with many able to reduce medications to only one or even eliminate them.12-14 Significant IOP and medication reduction have also been seen across various types and levels of severity of glaucoma.15

Patients should always be given realistic expectations based on each individual case as glaucoma is progressive and promising patients a cure-all only sets them up for dissatisfaction. However, most mild to moderate eyes have excellent potential for reduction or elimination of medications while still achieving the needed pressure reduction. This aids in delaying more invasive treatments and relieves the medication burden and its proven related complications, which can vastly improve patient quality of life. Adding no risk to the cataract procedure that is already being performed, it is in patients’ best interests to educate them on the option of incorporating iStent inject W into their treatment plan.

Mark Gallardo, MD practices with El Paso Eye Surgeons in El Paso, TX and holds faculty positions at The University of Texas Health Sciences Center in San Antonio, Texas Tech University School of Medicine in Lubbock, and the Paul L. Foster Texas School of Medicine in El Paso. He may be reached via email at [email protected].

Disclosures: Dr Mark Gallardo is a clinical investigator speaker for Glaukos.

Tham YC, Li X, Wong TY, et al. Global prevalence of glaucoma and projections of glaucoma burden through 2040: a systematic review and meta-analysis. Ophthalmol. 2014;121(11):2081–2090. DOI: 10.1016/j.ophtha.2014.05.013.

Erb C. Prevalence of dry eye disease in glaucoma. Eur Ophth. 2009;DOI:10.17925/EOR.2009.03.02.49.

Ayaki M, Noda Y, Yaguchi S, et al. Cytotoxicity of antiglaucoma ophthalmic solutions for human corneal endothelial cells [in Japanese]. Nippon Ganka Gakkai Zasshi. 2009;113(5):576-582.

De Saint Jean M, Brignole F, Bringuier AF, et al. Effects of benzalkonium chloride on growth and survival of Chang conjunctival cells. Invest Ophthalmol Vis Sci. 1999;40(3):619-630.

Arita R, Itoh K, Maeda S, et al. Comparison of the long-term effects of various topical antiglaucoma medications on meibomian glands. Cornea. 2012;31:1229-1234.

Wang PX, Koh VT, Cheng JF. Periorbital muscle atrophy associated with topical bimatoprost therapy. Clin Ophthalmol. 2014;8:311-4. DOI: 10.2147/OPTH.S55754. eCollection 2014.

Okeke CO, Quigley HA, Jampel HD, et al. Adherence with topical glaucoma medication monitored electronically the Travatan Dosing Aid study. Ophthalmol. 2009;116(2):191-9.

Sheer R, Bunniran S, Uribe C, et al. Predictors of nonadherence to topical intraocular pressure reduction medications among medicare members: A claims-based retrospective cohort study. J Manag Care Spec Pharm. 2016;22(7):808-817a.

Samuelson TW, Sarkisian SR, Lubeck DM, et al. Prospective, randomized, controlled pivotal trial of an ab interno implanted trabecular micro-bypass in primary open-angle glaucoma and cataract. Ophthalmol. 2019;126(6):811-821.

Fea AM, Belda JI, Rekas M, et al. Prospective unmasked randomized evaluation of the iStent inject versus two ocular hypotensive agents in patients with primary open-angle glaucoma. Clin Ophthalmol. 2014;8:875–882. doi:10.2147/opth.s59932.

Voskanyan L, García-Feijoó J, Belda JI, et al. Prospective, unmasked evaluation of the iStent inject system for open-angle glaucoma: synergy trial. Adv Ther. 2014;31(2):189–201. DOI: 10.1007/s12325-014-0095-y.

Katz LJ, Erb C, Carceller Guillamet A, et al. Long-term titrated IOP control with one, two, or three trabecular micro-bypass stents in open-angle glaucoma subjects on topical hypotensive medication: 42-month outcomes. Clinical Ophthalmology (Auckland, NZ). 2018;12:255-262.

Belovay GW, Naqi A, Chan BJ, et al. Using multiple trabecular micro-bypass stents in cataract patients to treat open-angle glaucoma. J Cataract Refract Surg. 2012;38(11):1911-1917.

Lindstrom R, Lewis R, Hornbeak DM, et al. Outcomes following implantation of two second-generation trabecular micro-bypass stents in patients with open-angle glaucoma on one medication: 18-month follow-up. Adv Ther. 2016;33(11):2082-2090. doi:10.1007/s12325-016-0420-8.

Hengerer FH, Auffarth GU, Riffel C, et al. Prospective, non-randomized, 36-month study of second-generation trabecular micro-bypass stents with phacoemulsification in eyes with various types of glaucoma. Ophthalmol Ther. 2018;7(2):405