This 68-year-old woman has visually significant cataract and advanced glaucoma in both eyes. Although the reader might have anticipated a diagnosis of advanced glaucoma in the left eye, the diagnosis is the same in the right eye because there is a deep visual field defect within 5 degrees of fixation. The parafoveal defect in the right eye is present on most of the field tests and is likely absent on 1 visual field test because of the sparse special sampling of the 24-2 pattern. However, this diagnosis affects the selection of procedures for this patient because the 2 currently available stents for concomitant placement at the time of cataract extraction exclude a diagnosis of advanced glaucoma, as per U.S. Food and Drug Administration labeling. The second aspect of paracentral visual field defects is that problematic acute IOP elevations can occur with the placement of microstents.
This patient has some flexibility in terms of goals for remaining drop-free after cataract extraction, and her reasonably controlled IOPs would seem to rule out performing a major incisional glaucoma surgery such as trabeculectomy or a tube shunt placement. The right parafoveal defect has likely deepened or progressed since 2009, although the left arcuate scotoma appears more stable.
In this case, I would approach the cataract in the right eye first. I would suggest a limited (< 3 clock hours) goniotomy performed with a dual blade, and I would augment this procedure with ab internal viscocanalostomy to allow access to the canal and to enhance the function of the canal through dilation. I have performed these procedures in eyes with chronic anticoagulation, and my approach has been to keep the eye fully pressurized during the procedure and to leave a small amount of dispersive ophthalmic viscosurgical device in the angle at the cessation of the case. I would pressurize the eye at the conclusion of the case and I would use a single dose of oral acetazolamide postoperatively (because of the parafoveal loss). It is my experience that with such patients, intraoperative bleeding and perioperative bleeding are more of an issue than chronic postoperative hyphema, although all possibilities should be discussed.
For the left eye, which has much more severe glaucoma, I would assess the outcome of the first eye’s procedure. If the results were highly satisfactory, I would repeat the procedure. If not, I would discuss the risks and benefits of placing a subconjunctival gel stent with the second cataract surgery, making sure that the patient understood that postoperative bleb manipulation might be required. Although the need for ongoing anticoagulation would affect the goniotomy size, surgical technique, and informed consent process, I would generally support a similar approach with or without the need for chronic anticoagulation.