Several features of this case, in addition to the provided information, should be considered when determining management and possible surgical intervention. Initially, we would like to review other information, including serial optical coherence tomography retinal nerve fiber layer assessment and the known maximum-treated or untreated IOP, to assist in characterizing the patient’s overall glaucoma stability. An IOP of 15 to 16 mm Hg seems acceptable; however, additional information could help determine whether the structural changes are as stable as the functional changes indicated in the provided visual field testing.
It is clear that the patient in this case has symptomatic cataracts that would benefit from cataract surgery. In patients on chronic anticoagulation desiring cataract surgery, it is rare to require interruption of anticoagulation therapy. We do, however, prefer to avoid retrobulbar anesthesia, thereby minimizing the risk for a retrobulbar hemorrhage. In the setting of an anticipant glaucoma surgery, the patient’s anticoagulation status has greater implications, and if permissible by her cardiologist we might transiently stop the patient’s medication to minimize the risk for intraoperative complications. There are certainly interventions that can be pursued despite being anticoagulated. However, if traditional incisional glaucoma surgeries are required, a discussion with the cardiologist might be warranted to inquire whether the patient could discontinue warfarin and bridge with an alternative medication. The risk for a suprachoroidal hemorrhage after tube shunts and trabeculectomies is increased with anticoagulation.
For this patient, we would favor the use of a MIGS drainage device at the time of cataract removal in each eye. Our choice of implant would also be affected by the patient’s anticoagulation status. We would avoid procedures that are prone to bleeding, such as a Kahook dual blade or goniotomy. We would also avoid the supraciliary space. Canal microshunt devices in the setting of chronic anticoagulation carry a safety profile that is favorable. In particular, the risk for hypotony would be reduced because these devices enhance the normal outflow pathway where basal episcleral venous pressure should serve to prevent critically low IOPs. Moreover, even if the patient could tolerate an interruption in the anticoagulation therapy, her glaucoma stability does not merit an aggressive reduction in IOP; therefore, we would avoid more intensive techniques such as trabeculectomy or tube shunt or suprachoroidal shunt placement.
Although we might gravitate toward the use of a MIGS procedure at the time of cataract removal, whether there is a need for further glaucoma intervention at this point could be contended, especially considering that the patient has stable IOP and visual fields, is compliant, and tolerates the topical therapy.
In summary, after a thorough discussion of the risks, benefits, and alternatives of surgery, we would proceed with cataract surgery with microbypass stent placement in both eyes. We prefer to avoid retrobulbar anesthesia, incisional glaucoma surgery, and the supraciliary space in patients who require anticoagulation. Micropulse could also be considered in the future if a lower IOP is required. In this case, even if the patient could discontinue warfarin, we would still proceed with combined cataract surgery and microbypass stent placement in both eyes.