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6 Advanced glaucoma treatment: Diagnostics, pharmaceuticals, and surgical options 6 2. Sleath B, et al. The relationship between glaucoma medication adherence, eye drop technique, and visual field defect severity. Ophthalmology. 2011;118:2398–2402. 3. Saheb H, et al. Micro-invasive glau- coma surgery: current perspectives and future directions. Curr Opin Ophthalmol. 2012;23:96–104. 4. Samuelson TW, et al. Randomized evalu- ation of the trabecular micro-bypass stent with phacoemulsification in patients with glaucoma and cataract. Ophthalmology. 2011;118:459–467. 5. Craven ER, et al. Cataract surgery with trabecular micro-bypass stent implan- tation in patients with mild-to-moderate open-angle glaucoma and cataract: two- year follow-up. J Cataract Refract Surg. 2012;38:1339–1345. 6. Belovay GW, et al. Using multiple trabecular micro-bypass stents in cataract patients to treat open-angle glaucoma. J Cataract Refract Surg. 2012;38:1911– 1917. 7. Fernández-Barrientos Y, et al. Fluoropho- tometric study of the effect of the Glaukos trabecular microbypass stent on aqueous humor dynamics. Invest Ophthalmol Vis Sci. 2010;51:3327–3332. Dr. Ahmed is professor of ophthal- mology, University of Utah, assistant professor of ophthalmology, Universi- ty of Toronto, and head of ophthal- mology, Trillium Health Partners, Mississauga, Ontario, Canada. He can be contacted at ike.ahmed@ utoronto.ca. With multiple trabecular mi- cro-bypass stents, we can achieve pressures in the low teens and reduce medication. Using 2 or 3 micro-bypass stents along with cataract surgery in 53 eyes, Belovay et al. reported that the overall mean IOP was 14.3 mm Hg 1 year after surgery, and topical medication was reduced in 83% of eyes 1 year after surgery. 6 When Fernández-Barrientos et al. compared phacoemulsifi- cation with 2 stents (17 eyes) vs. phacoemulsification alone (16 eyes), the combination reduced medications and IOP and in- creased outflow significantly over phaco alone. 7 New Schlemm's canal pro- cedures are emerging to enhance outflow, which we can compare with current procedures. Su- prachoroidal devices are intrigu- ing because they rely on space in the suprachoroidal outflow track. Conclusion Ophthalmologists have an array of options to reduce IOP, and new procedures will become available. When choosing procedures, it is important to compare risk vs. benefit vs. effort in patient selection. References 1. Nordstrom BL, et al. Persistence and adherence with topical glaucoma therapy. Am J Ophthalmol. 2005;140:598–606. cataract surgery, efficacy is par- ticularly important. As internal stenting may not be enough to reach target IOP, we are more likely to proceed with a solo bleb procedure. We are moving toward micro-stenting approaches. Internal MIGS procedures have shown high safety, and there are differences in the canal and suprachoroidal space. Schlemm's canal is safe, but the procedure is slightly more difficult and efficacy is modest. Suprachoroidal devices have a significant potential space, but variability depends on healing and efficacy has been modest. The Schlemm's canal micro- stent (iStent) is the only MIGS device available in the United States. Early results were modest; Samuelson et al. reported that 22% more patients who received this device with cataract surgery achieved the study primary end- point (normal IOP) vs. those who had cataract phacoemulsification alone. 4,5 To increase IOP reduction, we need to place the micro-stent in the vicinity of 1 of the major aqueous outflow channels rather than placing it where there are no collectors or a high-resistance plexus system, which will be less likely to reduce IOP (Figure 1). Blood reflex and pigmenta- tion can provide an indication of where to target MIGS devices (Figure 2). Hg). Patients are intolerant to medications. When weighing glaucoma procedures, an important consid- eration is whether we will be able to decrease or eliminate medica- tions. Even if the IOP remains the same, cessation of medications is a very important outcome measure and addresses adherence challenges. Bleb vs. bleb-less There are 3 MIGS outflow tracks: Schlemm's canal (conventional outflow), suprachoroidal space, and subconjunctival space (non- conventional outflow). One of the most important questions is whether we will drain externally (bleb forming) or inter- nally (bleb-less), which depends on whether cataract surgery is performed. Phacoemulsification reduces IOP, and combining phacoemulsification with bleb surgery increases the risk of bleb failure. However, phacoemulsifi- cation and internal MIGS work synergistically. Using a 2-stage approach, performing phacoemulsification plus internal MIGS, protects against early IOP spikes, with no impact on future bleb success. We can perform a bleb procedure later, if needed. However, when performing a standalone procedure without continued from page 5 Figure 2. Blood reflex and pigmentation can provide an indication of where to target placement of MIGS devices.

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