Surgery for Poag in an Eye With Prior Conjunctival Problems

CASE PRESENTATION

An 82-year-old man with a history of advanced primary open-angle glaucoma in both eyes presented for a glaucoma follow-up examination. The disease was end stage in his right eye. The patient's ocular medications included dorzolamide 2%–timolol 0.5% b.i.d., brimonidine 0.15% t.i.d., and latanoprost 0.005% q.h.s. in both eyes. The patient used eye drops infrequently OD due to his tendency to refill prescriptions irregularly and his preference to instill eye drops in his seeing left eye. His vision was light perception OD and 20/50 OS with a right afferent pupillary defect. The IOP measured 36 mm Hg OD and 13 mm Hg OS. The central corneal thickness was 551 μm OD and 548 μm OS.

A slit-lamp examination was unremarkable. Fundoscopy OS showed a cup-to-disc ratio of 0.95 and attenuated vessels. Figure 1A illustrates the advanced disc disease OS, and Figure 1B documents the thinning of the retinal nerve fiber layer in the same eye. Current 24-2 and 10-2 visual field analysis showed a progression of inferior loss from the patient's last test (Figure 2). He was on maximal medical therapy and had an average IOP of 16.6 mm Hg and a maximum IOP of 20 mm Hg OS on his current medications.

The patient's ocular history included surgical interventions. He had undergone argon laser trabeculoplasty 180^o in his left eye in 1989. In 1993, he underwent a trabeculectomy in his right eye. He also underwent cataract surgery with the placement of a PCIOL in his right eye in 2005 and then in his left eye in May 2008.

The patient's history of postoperative complications includes a bleb leak after trabeculectomy in his right eye that required repair in 1993. During the 2008 cataract procedure in his left eye, a second-site, limbus-based trabeculectomy by an experienced glaucoma surgeon was aborted due to conjunctival friability. One month postoperatively, the patient had a corneal defect that caused his vision to decrease to 20/200 OS. His vision recovered to 20/20-34 months postoperatively, after the cessation of topical steroids. With a visual acuity of only light perception in his right eye, the patient was extremely worried about further procedures on his left eye. He lives alone and was concerned that blurred vision postoperatively would inhibit his ability to perform his daily activities.

HOW WOULD YOU PROCEED?

• Would you continue medical management?
• Would you retry a trabeculectomy on the patient's left eye with mitomycin C (MMC) and/or use an Ex-Press Glaucoma Filtration Device (Alcon Laboratories, Inc.)?
• Would you place a glaucoma tube implant?
• Would you perform cyclophotocoagulation?

SURGICAL COURSE

We decided to perform a fornix-based trabeculectomy flap with MMC and to implant an Ex-Press device under the flap in the patient's left eye. We chose the implant based on evidence that visual recovery is faster following its placement versus standard trabeculectomy.¹ The speed of visual recovery was especially important due to the patient's solitary living situation and his need to perform daily activities.

OUTCOME

Preoperatively, the patient's visual acuity was light perception in his right eye and 20/40+2 in his left eye. On the first postoperative day, his visual acuity remained light perception in the right eye and 20/40-2 in the left eye. He was treated with prednisolone acetate 1% every 2 hours OS with a taper and moxifloxacin 0.5% q.i.d. OS for 2 weeks. The visual acuity in his left eye worsened on the fourth postoperative day, which we attributed to dryness and irritation of the ocular surface. One month postoperatively, however, the patient's left eye had punctate epithelial erosions on the cornea, trace inflammation in the anterior chamber, and cystoid macular edema (CME), as shown on optical coherence tomography.

In response, we increased the prednisolone to six times per day, and we prescribed bromfenac (Bromday; Bausch + Lomb) q.d. OS. After the discontinuation of the anti-inflammatory medications 3 months postoperatively, the patient again presented with a sudden decrease in vision (20/100-1 BCVA) that occurred over the course of 1 week. We diagnosed recurrent CME in his left eye and started him on ketorolac (Acular; Allergan, Inc.) q.i.d. The CME resolved within 1 month and the drops were stopped. The patient's visual acuity remained stable (20/20) through 20 months postoperatively.

On the third and 10th days postoperatively, the patient's IOP in the left eye was 6 mm Hg and 5 mm Hg. Although the placement of an Ex-Press is associated with a risk of hypotony,² the patient's postoperative IOP was near the acceptable range of 5 to 21 mm Hg. The patient did not take the prednisolone as frequently as was prescribed, which may have contributed to the low IOP. During the episodes of CME, the IOP remained in the acceptable range of 8 to 9 mm Hg. Figure 3 shows the pattern of the IOP in the patient's left eye, which remained in the range of 8 to 11 mm Hg through 20 months. According to the Advanced Glaucoma Intervention Study (AGIS), this represents a successful outcome.³ Figures 4 and 5 show the appearance of the patient's eye 6 months postoperatively.

DISCUSSION

The patient in this case had an extensive history of variable compliance with his medications, and preoperative therapy did not adequately control his IOP.

According to results of the AGIS, there is a difference in the worsening of visual field scores, as defined within the study, between patients with an IOP less than 14 mm Hg versus those with an IOP greater than 17.5 mm Hg. We considered the patient to have failed medical and laser surgery with progression at the obtained IOP range to 20 mm Hg. With the need for optimal management and preservation of his left eye, we pursued further options with a goal of shifting the IOP range to 14 mm Hg and under.

Cyclophotocoagulation was an option for this patient, but the transscleral and endoscopic methods of cyclophotocoagulation show varying rates of success for treating glaucoma.^4-6 Transscleral cyclophotocoagulation therapy can pose a relatively high risk for vision loss and other serious complications.^4,5 Some of these results may be due to advanced pathology, and fewer complications may arise when cyclophotocoagulation is used as a primary treatment.⁶ We considered our patient to be a poor candidate for cyclophotocoagulation, however, due to his monovision and the possibility of an adverse outcome. We also needed to avoid the risk of an acute rise in IOP after cyclophotocoagulation. The filtration surgery quickly reduced the IOP.

Although tube implants have been shown to effectively lower IOP and are often the procedure of choice following a failed trabeculectomy,⁷ the conjunctiva and Tenon capsule away from the limbus in this patient's left eye were noted to be extremely delicate in 2008. The operative report was reviewed, and blunt dissection with a Weck-Cel sponge (Beaver-Visitec International) created a buttonhole defect, leading to the aborted trabeculectomy. We therefore decided against a tube implant in this case. In our selection of a fornix-based trabeculectomy flap, we considered that this approach allows for less manipulation of the tissue and is considered an easier technique in eyes with scarred conjunctiva compared with a limbus-based approach.⁸ Although Kohl and Walton reported that fornix-based trabeculectomies have more frequent early bleb leaks postoperatively,

They heal spontaneously or with the use of a bandage contact lens.⁸ Although our patient had a history of postoperative bleb leak with a prior limbus-based procedure in the right eye, this was likely due to the minimal Tenon layer, which is not as important for the support of a fornix-based conjunctival wound. We chose a fornix-based method, therefore, due to the patient's previous complications of the conjunctiva in both eyes related to limbus-based incisions. The postoperative complications of CME and toxic epithelial disease intermittently decreased the patient's vision but not to a level that made him unable to care for himself. Thus far, these problems have not been linked to the Ex-Press and can occur with any procedure of the anterior segment.