A 75-year-old black female presented as a new patient in 2008 after relocating to the area. She had a complicated eight-year history of glaucoma in both eyes. Her IOP was slowly rising. Her vision was diminishing. Her meds were maxed out. Previous surgical options had failed. What’s the next step?

Her ocular medications included 1gtt Xalatan (latanoprost, Pfizer) O.D. h.s., 1gtt Combigan (brimonidine/timolol, Allergan) O.D. b.i.d., 1gtt dorzolamide O.D. b.i.d. and 500mg Diamox Sequels (acetazolamide, Teva Pharmaceuticals) b.i.d. She was taking no topical medications O.S. Her systemic medications included Lipitor (atorvastatin calcium, Pfizer), HCTZ, and potassium supplements. She reported no known allergies to any medications.

In viewing her records, I noted that she was initially diagnosed with pressure-dependant glaucoma. Her pretreatment IOP was documented in the mid- to upper 30s in both eyes. At the time of diagnosis, she already had significant glaucomatous optic neuropathy with cup-to-disc ratios estimated at 0.80 x 0.80 O.U. by her previous provider.

Initial medical therapy with several different agents reduced her IOP to the low 20s. Eventually, however, she underwent seven argon laser trabeculoplasty (ALT) procedures (three in her right eye, four in her left eye). Her records showed that her IOP varied significantly between ALT procedures. Also, her visual fields and neuroretinal rims deteriorated slightly. All the while, she remained relatively compliant with her medications.

In 2006, her previous eye care provider recommended that she undergo bilateral trabeculectomy to reduce and stabilize her IOP. Immediately following the procedures (O.D. fall 2006, O.S. winter 2007), her IOP dropped into the mid-teens in both eyes. From her records, it was not clear if antimetabolites, such as mitomycin C (MMC) or 5-FU, were used during the procedures. However, her records did indicate that within a few months post-op, the bleb in her right eye flattened and was questionably patent.

Diagnostic Data
When I first saw the patient in mid-2008, her uncorrected visual acuity measured 20/200 O.D. and 20/300 O.S. Best-corrected visual acuity was 20/80 O.D. and 20/100 O.S., with no improvement upon pinhole testing. Her pupils were relatively equal; however, both pupillary margins were mildly distorted following trabeculectomy. There was no afferent pupillary defect. Her intraocular pressure measured 20mm Hg O.D. and 12mm Hg O.S.

A slit lamp examination of her anterior segments revealed mild central corneal guttatae in both eyes. There were bilateral surgical iridectomies located superiorly. The bleb in her left eye was well formed, with no leakage or evidence of blebitis. However, the right bleb appeared flat and avascular.

Gonioscopy indicated grade IV+ open angles O.U. The right superior sclerostomy did not appear to be patent; however, the superior sclerostomy in her left eye did appear to open into the overlying bleb. The patient also had posterior chamber IOLs in both eyes; both posterior capsules were opened. Central corneal thickness measured 547µm O.D. and 550µm O.S.

Through dilated pupils, both IOLs appeared well centered in the capsular bags. Bilateral posterior vitreous detachments (PVDs) were present. Her cup-to-disc ratio measured 0.95 x 0.95 O.D. and 0.85 x 0.90 O.S. She had complete loss of the neuroretinal rim from 3 o’clock to 9 o’clock in her right eye and 12 o’clock to 6 o’clock in her left eye.

Her macular evaluations demonstrated bilateral epiretinal membranes (ERMs), which were more significant in her left eye than her right eye. The variations in her ERMs accounted for her disparities in best-corrected visual acuity. There was mild hypertensive and arteriolarsclerotic retinopathy located bilaterally. Her peripheral retinal examinations were essentially unremarkable in both eyes.

Given that this was her first visit, I made no changes to her therapeutic regimen and scheduled her to return in two months.

At her two-month follow-up, threshold field studies revealed significant field constriction in both eyes as well as excessively long testing times and high fixation losses. Her previous field tests also suggested that she had difficulty performing threshold perimetry. Heidelberg Retina Tomograph-3 (HRT-3, Heidelberg Engineering) confirmed the presence of neuroretinal rim loss in both eyes. Her IOP measured 20mm Hg O.D. and 14mm Hg O.S. She was still tolerating her medications well.

During the next 18 months, her left eye remained stable in all respects. However, the IOP in her right eye varied widely and gradually increased.

In March 2010, her IOP peaked at 34mm Hg O.D. and 15mm Hg O.S. Given the advanced optic nerve damage in her right eye as well as her unstable and elevated IOP levels, it was clear that a different intervention strategy was necessary.

Discussion
So, where do we go from here? Selective laser trabeculoplasty (SLT) is a possible option; however, the procedure would not likely decrease her IOP significantly. In some cases of advanced glaucoma, even a modest IOP reduction following SLT can make a difference in the patient’s long-term management. In this case, her IOP should really be less than 12mm Hg O.D. But, the likelihood of SLT reducing IOP to that target level is exceedingly rare.

Another option is a revision of her existing trabeculectomy, or perhaps even a new trabeculectomy with an antimetabolite. But, after consulting with our glaucoma surgeon, there were two reasons why a fresh trabeculectomy might not work. First, her original trabeculectomy failed. While this does not guarantee that the second procedure will fail, it did not give us a good feeling about her long-term stability. Second, given the size and location of her first trabeculectomy, there simply was not enough room to create a new bleb in an area protected by her lids.

So, we discussed other options, including tubes, shunts and cyclocryotherapy. After reading the results of the Tube vs. Trabeculectomy (TVT)
study and having a discussion with our glaucoma surgeon, we believed that our patient would be better suited for a Baerveldt glaucoma implant (Abbott Medical Optics) than a ciliary body ablation.¹

The TVT study evaluated patients with uncontrolled glaucoma who also had undergone previous trabeculectomy and/or cataract surgery with IOL implantation.¹ In the study, 212 patients either underwent trabeculectomy with MMC or received a 350mm Baerveldt implant. The three-year results indicated that patients from both groups experienced an adequate reduction in IOP and consequently required fewer glaucoma medications.¹ Patients in the trabeculectomy group, however, suffered higher failure and complication rates.

Baerveldt implants, in particular, have been shown to be beneficial in cases of uncontrolled glaucoma and/or when conventional therapy fails.^2,3 The implant acts as a substrate for bleb creation, and allows the clinician to insert a silicone cannula that extends into the anterior chamber. These implants are very useful for more recalcitrant conditions, such as neovascular, congenital, uveitic, and poorly controlled aphakic and pseudophakic glaucomas.

In mid-June, the patient underwent an uncomplicated Baerveldt implantation in her right eye. The surgeon made a paracentesis stab to control IOP spikes during the immediate postoperative period.

The postoperative care of these patients requires close monitoring for the first several weeks. In addition to glaucoma medications, patients should be treated with a regimen of antibiotics, such as Zymar (gatifloxacin, Allergan) or Vigamox (moxifloxacin, Alcon) q4h to q6h, as well as Pred Forte (prednisolone acetate 1%, Allergan) q4h to q6h. Glaucoma medications should be titrated according to immediate postoperative IOP levels. Topical antibiotics are utilized for the first two weeks and periodically thereafter if the anterior chamber is tapped through the paracentesis and IOP elevates significantly. The topical steroid should be tapered according to anterior chamber activity.

When we last saw the patient on July 18, her intraocular pressure measured 6mm Hg O.D. Topical medications included Pred Forte q.i.d. and Xibrom (bromfenac, ISTA Pharmaceuticals) b.i.d. She was taking no topical or oral glaucoma medications.

While her current IOP is low and her anterior chamber is relatively quiet, our patient still needs to be monitored closely for hypotonous complications, such as choroidal effusions, maculopathy and flat anterior chambers. Hopefully, she will do well, because further management options are limited.

1. Gedde SJ, Schiffman JC, Feuer WJ, et al. Three-year follow-up of the tube versus trabeculectomy study. Am J Ophthalmol. 2009 Nov;148(5):670-84.
2. Jacob J, Stalmans I, Zeyen T. Ahmed and Baerveldt glaucoma drainage implants: long-term results and factors influencing outcome. Bull Soc Belge Ophtalmol. 2009;(313):19-29.
3. Anand A, Tello C, Sidoti PA, et al. Sequential glaucoma implants in refractory glaucoma. Am J Ophthalmol. 2010 Jan;149(1):95-101.