A 50-year-old male electrical engineer was referred to the glaucoma unit at St. Michael's Hospital on October 20, 2010, for left uncontrolled low-tension glaucoma on maximum medical therapy. His past ocular history included a right eye trabeculectomy, followed by a right Ahmed valve placement and right cataract extraction with lens implantation in 2006. In the left eye, a left Ahmed valve was placed in 2007. A diagnosis of low-tension glaucoma had been previously established by the referring glaucoma specialist. The patient had progressive visual field loss despite IOP in the teens, with multiple failed filtration surgeries. He was highly myopic at -14.00 D in each eye. His family history was negative for glaucoma, and he had a history of remote inhaled steroid use of several months duration. Past medical history included a resolved tuberculosis infection 16 years earlier.
At the time of his visit, he was using brinzolamide 1% tid OU, brimonidine bid OU, timolol 0.5% once am OU, and bimatoprost 0.01% at hs OU. On examination, hand vitiligo was noted. Best corrected visual acuity was 20/30 OD and 20/40 OS and IOPs were 12 mmHg OD and 16 mmHg OS at 12:35 pm. Ocular motility was full, and pupils were equally reactive to light with no afferent pupillary defect. There was marked injection of the inferior lid margins and conjunctiva. Corneal thicknesses were 574 and 576 microm in the right and left eyes, respectively. The right anterior chamber showed a tube entering at the 11 o'clock position and the left anterior chamber showed a tube entering at the 4 o'clock position in the presence of iridotomies superiorly. Angles were wide open, and right posterior chamber intraocular lens was in good position. Early nuclear sclerosis was seen in the left eye. Right optic nerve head revealed severe cupping, and the left optic nerve revealed a 0.8 cup with superonasal neuroretinal rim remaining. Shallow excavation was noted in both eyes. Large temporal zones of beta parapapillary atrophy were also noted. Visual field tests showed right superior hemifield loss splitting fixation and left superior arcuate changes approaching fixation. Left visual field progression over 2 years was documented (Figure 1A and B).
In view of uncontrolled, end-stage, low-tension glaucoma with advanced progressive field loss and IOP in high teens on maximal medical therapy, the options of trabeculectomy with or without cataract extraction and intraocular lens implantation were discussed in detail with the patient. After discussing the benefits and risks of the procedure, the patient elected to proceed with combined left trabeculectomy, cataract extraction, and intraocular lens implantation with mitomycin C. The surgery was performed on November 30, 2010. Several weeks after the surgery, he underwent bleb needling due to rapid scarring and remained uncontrolled despite reinstituting maximal medical therapy. The option of gold shunt surgery was discussed to bypass conjunctival scarring issues, including the benefits and risks, and the patient elected to proceed with gold shunt surgery.
On February 22, 2011, left uncomplicated gold shunt surgery was performed. On the first day after the surgery, best corrected visual acuity was 20/200 OS, IOP measured 6 mmHg OS at 4:20 pm, with trace anterior chamber reaction. He was treated with ofloxacin qid and prednisolone 1% qh for 5 weeks. Left eye visual acuity improved, and IOP remained low over the first 3 months. On July 13, 2011, best corrected visual acuity was 20/20 OD and 20/30+2 OS. Intraocular pressures remained mostly in the low teens, using two glaucoma medications in the right eye only. The gold shunt remained in good position and glaucoma appeared stable (Figure 2A and B). Over a 5-year follow-up period, visual acuity (VA), IOPs, and glaucoma remained stable. On May 27, 2015, best corrected visual acuity was 20/30+2 OD, 20/25-2 OS, and IOP measured 14 mmHg OU at 11:35 am, with no changes in medication. The gold shunt continued to be in good position, and glaucomatous optic neuropathy remained stable (Figure 3A and B). Visual fields remained stable throughout the period of follow-up (Figure 4A-D). At his last visit on October 26, 2015, IOP measured 10 mmHg OU and 12 mmHg OS, with no changes in medication. St. Michael's Hospital Research Ethics Board approval was obtained for this case report, and the patient provided written informed consent.