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Consultation section: Glaucoma

January consultation #3

Shah, Manjool MD

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Journal of Cataract & Refractive Surgery: January 2018 - Volume 44 - Issue 1 - p 112-114
doi: 10.1016/j.jcrs.2018.01.007
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In this patient with a visually significant cataract and stable POAG in both eyes, numerous opportunities exist in addressing both conditions with a single trip to the operating room. I would assure this patient that because she has relatively thin CCT and is young enough, the glaucoma would remain stable for at least the next decade or 2. Given these facts, although it is well controlled in the mid teens on 2 classes of medication, I would welcome a mild reduction in the patient’s IOP through surgical intervention. The patient’s requirement for chronic anticoagulation therapy with warfarin is relevant in that it will narrow the option set for adjunctive glaucoma procedures to some degree.

Microinvasive glaucoma surgery (MIGS) options would be ideal in this patient’s situation given the optimal safety profile combined with the requirement for modest pressure reduction. Because the patient can easily tolerate the ocular hypotensive agents prescribed at present and is willing to continue them as needed postoperatively, I would favor a less aggressive glaucoma adjunctive procedure in general. Safety during the postoperative period and a mitigation of postoperative risks and complications would be my primary goals. Certainly, traditional filtration surgeries with their baseline risks for hemorrhagic complications are not indicated in this setting.1 Another secondary role of combining cataract surgery with an adjunctive MIGS procedure is the theoretical risk reduction in early postoperative pressure spikes. Although medical therapy might be sufficient to mitigate this risk in many situations, Weiner et al.2 found better early postoperative risk mitigation with ab interno trabeculotomy.

In the right eye, with fairly mild to moderate disease but the occasional presence of a central scotoma, a Schlemm canal surgical target with a trabecular meshwork microbypass stent would be my preferred adjunct to standard cataract extraction. Although a theoretical risk for postoperative hyphema exists,3 this rate is likely lower than that for other incisional ab interno trabeculotomy techniques. As such, I would avoid techniques such as gonioscopy-assisted transluminal trabeculotomy4 or instruments such as the Trab360 (Sight Sciences), Trabectome (Neomedix Corp.), or Kahook Dual Blade (New World Medical, Inc.). The findings of Ahuja et al.5 can likely be applied to these other techniques, especially because the primary goal is to maximize safety. If the patient were not anticoagulated, ab interno trabeculotomy could be considered in the option set.

In the left eye with more severe glaucoma, I would consider 2 potential surgical options. A Schlemm canal–based approach similar to that in the right eye would be reasonable given the stable visual fields and well-tolerated medications. However, given the presence of visual field compromise relatively close to fixation in a patient with many decades of vision ahead of her, I would strongly consider trying to achieve a lower pressure than a Schlemm canal–based approach often can provide. I would therefore offer the patient a subconjunctival microfistula implant such as the Xen gel stent (Allergan, Inc.). The favorable risk profile with more profound pressure-lowering results might be ideal in this setting. Although hemorrhagic complications of this procedure have also been reported,6 the incidence is much lower than with traditional filtration.7 Furthermore, if the patient were unable to tolerate topical agents, the gel stent likely offers the best chance at eliminating medications and could also be considered for the right eye in that scenario.

References

1. Law SK, Song BJ, Yu F, Kurbanyan K, Yang T-A, Caprioli J. Hemorrhagic complications from glaucoma surgery in patients on anticoagulation therapy or antiplatelet therapy. Am J Ophthalmol. 2008;145:736-746.
2. Weiner Y, Severson ML, Weiner A. Intraocular pressure 3 to 4 hours and 20 hours after cataract surgery with and without ab interno trabeculectomy. J Cataract Refract Surg. 2015;41:2081-2091.
3. Sandhu S, Arora S, Edwards MC. (2016). A case of delayed-onset recurrent hyphema after iStent surgery. Can J Ophthalmol, 51, e165-e167, Available at: http://www.canadianjournalofophthalmology.ca/article/S0008-4182(16)30409-4/pdf Accessed 20-11-2017
4. Grover DS, Godfrey DG, Smith O, Feuer WJ, Montes de Oca I, Fellman RL. Gonioscopy-assisted transluminal trabeculotomy, ab interno trabeculotomy; technique report and preliminary results. Ophthalmology. 2014;121:855-861.
5. Ahuja Y, Malihi M, Sit AJ. Delayed-onset symptomatic hyphema after ab interno trabeculotomy surgery. Am J Ophthalmol. 2012;154:476-480.
6. Prokosch-Willing V, Vossmerbaeumer U, Hoffmann E, Pfeiffer N. Suprachoroidal bleeding after XEN gel implantation. J Glaucoma 2017 Sep 3. [Epub ahead of print].
7. Schlenker MB, Gulamhusein H, Conrad-Hengerer I, Somers A, Lenzhofer M, Stalmans I, Reitsamer H, Hengerer FH, Ahmed K II. Efficacy, safety, and risk factors for failure of standalone ab interno gelatin microstent implantation versus standalone trabeculectomy. Ophthalmology. 2017;124:1579-1588.
© 2018 by Lippincott Williams & Wilkins, Inc.