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Case report

Combined trabeculectomy and vitrectomy for pseudophakic malignant glaucoma and extensive peripheral anterior synechia-induced secondary glaucoma

Tsai, Yi-Yu MD*,a,b; Tseng, Sung Huei MDc

Author Information
Journal of Cataract & Refractive Surgery: March 2004 - Volume 30 - Issue 3 - p 715-717
doi: 10.1016/S0886-3350(03)00665-5
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Abstract

Malignant glaucoma is a relatively rare form of angle-closure glaucoma that results from misdirection of aqueous humor into the vitreous cavity. It occurs most commonly after intraocular surgery.1 In eyes that do not respond to medical or laser therapy, the surgical treatment is vitrectomy.2–6 If malignant glaucoma persists, extensive peripheral anterior synechias (PAS) will be induced because of a long-standing shallow anterior chamber. Hence, combined malignant glaucoma and PAS-induced secondary glaucoma will appear in patients with chronic malignant glaucoma. For patients with combined-mechanism glaucoma, vitrectomy alone may not be sufficient and further filtration surgery after vitrectomy or pars plana tube insertion with vitrectomy is recommended.2–6

We report a case of angle-closure glaucoma after phacoemulsification in which glaucoma was diagnosed as combined malignant and PAS-induced glaucoma. Simultaneous trabeculectomy and vitrectomy via the peripheral iridectomy successfully lowered the intraocular pressure (IOP) and deepened the anterior chamber. To our knowledge, this is the first description of combined trabeculectomy and vitrectomy.

Case Report

A 66-year-old woman had uneventful phacoemulsification and intraocular lens implantation in the right eye in December 1999. One week later, the patient had a shallow anterior chamber and high IOP (29 mm Hg). Angle-closure glaucoma was diagnosed, and timolol 2 times daily and pilocarpine 4 times daily were prescribed.

One month postoperatively, laser iridotomy was performed to prevent pupillary block glaucoma because posterior synechias were found. The IOP was controlled to between 14 mm Hg and 25 mm Hg; the anterior chamber remained shallow. One year postoperatively, brimonidine tartrate (Alphagan®) was also prescribed because the IOP was over 30 mm Hg. The next month, the IOP was over 40 mm Hg and a filtering procedure was suggested, but the patient refused. One month later, the patient was referred to our hospital because of persistent high IOP.

Slitlamp examination at our hospital in January 2001 revealed a shallow anterior chamber with iris attached to the peripheral cornea. A small pupil with posterior synechias was also found. Laser iridotomy was done at 6 o'clock. The IOP was 50 mm Hg. Ultrasound examination ruled out suprachoroidal hemorrhage. Chronic malignant glaucoma with superinduced PAS glaucoma was suspected because of the patient's medical history. Because the patient was taking the maximum amount of medication, surgical intervention was considered. Laser therapy could not be performed because of corneal edema and a shallow anterior chamber.

Combined-mechanism glaucoma was suspected, and combined vitrectomy and trabeculectomy was considered. Although pars plana vitrectomy (PPV) and trabeculectomy could be done simultaneously, the combined surgery was attempted.

Before the procedure, mannitol was given to reduce the IOP. Intraoperatively, a superotemporal limbus-based conjunctival flap and rectangular scleral flap at 11 o'clock were made, as in conventional trabeculectomy. After mitomycin-C (MMC) 0.02% supplementation for 2 minutes, chondroitin sulfate 4%–sodium hyaluronate 3% (Viscoat®) was injected into the anterior chamber through a paracentesis at 2 o'clock to deepen the anterior chamber. After punch excision of internal ostium and a peripheral iridectomy, vitrectomy could be performed. The anterior chamber was shallow and the IOP still high. The globe was hard, a condition not found in other glaucoma patients at this step of trabeculectomy.

An anterior vitrectomy was performed via the internal ostium, peripheral iridectomy was done (Figure 1), and an infusion of balanced salt solution (BSS®) by a Simcoe cannula via the paracentesis was done. The vitreous cutter was slowly moved between the peripheral iridectomy and pupil, and as much of the anterior vitreous as possible between the iridectomy and pupil was removed. Initially, the anterior chamber slowly deepened during vitrectomy. Eventually, the anterior chamber became deep and the globe soft, at which time communication between the anterior chamber and aqueous pool at the posterior chamber was considered to be established. The scleral flap was sutured after the partial anterior vitrectomy; the conjunctival flap was sutured as in conventional trabeculectomy.

Figure 1.
Figure 1.:
(Tsai) A cross-section view of combined trabeculectomy and vitrectomy. The vitreous cutter is introduced into the anterior chamber through internal ostium of the trabeculectomy and into the vitreous cavity through the peripheral iridectomy. The infusion cannula is not shown (* = the aqueous pool in the vitreous cavity).

One day postoperatively, the IOP was 10 mm Hg and the bleb was formed, but the anterior chamber was shallow. The anterior chamber gradually became deep, and the IOP decreased to between 13 mm Hg and 16 mm Hg without antiglaucoma medication. Six months later, the IOP was 13 mm Hg, the bleb was still formed, and the anterior chamber was deep. The suspected extensive PAS was confirmed by a goniolens after surgery.

Discussion

We suspected our patient had malignant glaucoma for the following reasons: The eye had a shallow anterior chamber that was normal preoperatively and the postoperative anterior chamber reaction was mild because an experienced surgeon performed the procedure and uneventful phacoemulsification. There was no history of angle-closure glaucoma before phacoemulsification or pupil block; posterior synechias were found at the initial stage of glaucoma. Ultrasound ruled out suprachoroidal hemorrhage. The globe was still hard after trabeculectomy, further evidence of malignant glaucoma. We suspected our patient had extensive PAS because the iris had been attached to the peripheral cornea for more than 15 months, a finding that was confirmed postoperatively.

Because our patient had combined-mechanism glaucoma, trabeculectomy alone could not lower the IOP and it flattened the anterior chamber intraoperatively because of forward pressure from the vitreous. Similarly, if PPV were performed alone, the IOP might have remained high postoperatively because of diffuse PAS. Hence, vitrectomy and trabeculectomy are necessary for patients with chronic malignant glaucoma and extensive PAS. Although PPV and trabeculectomy can be done simultaneously, it is time consuming. Thus, combined vitrectomy and filtration surgery is another option. Azuara-Blanco and coauthors3 recommend the use of combined PPV and pars plana tube shunt implantation. However, this technique requires vitreoretinal and tube shunt implantation surgical expertise. We describe combined trabeculectomy and vitrectomy, which is technically simple because the trabeculectomy is performed as in a conventional procedure and the anterior vitrectomy is similar to that used in complicated cataract surgery.

Vitrectomy through a peripheral iridectomy that is not pars plana to treat pseudophakic malignant glaucoma has been reported.2 Resolution of the malignant glaucoma was achieved in all 5 cases, and the authors recommend this technique (zonulohyaloidovitrectomy) as an alternative treatment for pseudophakic malignant glaucoma. We agree that vitrectomy through a peripheral iridectomy could replace standard PPV to manage pseudophakic malignant glaucoma. However, although there were no recurrences of malignant glaucoma in the study,2 1 patient had trabeculectomy after vitrectomy because of extensive anterior synechias. We suggest if diffuse PAS occur in patients with chronic malignant glaucoma, combined trabeculectomy and vitrectomy may be better than vitrectomy alone.

It is usually difficult to confirm the absence of PAS preoperatively in patients with chronic malignant glaucoma. If PAS are absent after the anterior chamber deepens and after combined trabeculectomy and vitrectomy is performed, the scleral flap must be sutured tightly. If diffuse PAS are present, the scleral flap and conjunctival wound are managed as in trabeculectomy. If the presence of PAS is still uncertain, a releasable suture or laser suturelysis technique is better.

Failure of a previous trabeculectomy with a flat bleb after resolution of malignant glaucoma by PPV or peripheral iridectomy vitrectomy has been reported.2,4–6 The cause is unknown. In our patient, MMC was used intraoperatively because vitrectomy (peripheral iridectomy or PPV) was planned before the procedure and the bleb was still formed after 6 months. We suggest using antimetabolites (eg, 5-fluorouracil or MMC) with combined trabeculectomy and vitrectomy.

Vitrectomy as performed in our technique establishes a pathway between the anterior chamber and aqueous pool in the vitreous cavity; thus, the anterior vitreous between the peripheral iridectomy and pupil is removed as much as possible. Although the vitreous cutter cannot be seen through peripheral iridectomy and the pupil all the time, using the cutter to move between them is safe. Care is taken to direct it away from the ciliary process and peripheral retina. It is sometimes unclear when the pathway between the anterior chamber and the aqueous pool in the vitreous cavity is established. In our case, the anterior chamber deepened slowly at first because the pathway was not formed and only vitreous was removed by the vitreous cutter. When the pathway was established, the anterior chamber suddenly became deep and the globe soft because the aqueous in the vitreous cavity escaped and infused BSS rapidly deepened the anterior chamber.

Combined trabeculectomy and vitrectomy can also be used in pseudophakic patients with glaucoma and a shallow or flat anterior chamber in whom it is difficult to differentiate malignant glaucoma and pupillary block or PAS-induced glaucoma. If surgical treatment is indicated, trabeculectomy is performed first. If the IOP remains high and the globe is still hard after punch excision of internal ostium and peripheral iridectomy, malignant glaucoma is diagnosed and vitrectomy via peripheral iridectomy is performed until the IOP is lowered and the anterior chamber deep. Moreover, if malignant glaucoma occurs during or after conventional glaucoma surgery, our vitrectomy procedure is also indicated; the patient should be pseudophakic and an posterior chamber problem (eg, suprachoroidal hemorrhage) must be ruled out.

References

1. Luntz MH, Rosenblatt M. Malignant glaucoma. Surv Ophthalmol 1987; 32:73-93
2. Lois N, Wong D, Groenewald C. New surgical approach in the management of pseudophakic malignant glaucoma. Ophthalmology 2001; 108:780-783
3. Azuara-Blanco A, Katz LJ, Gandham SB, Spaeth GL. Pars plana tube insertion of aqueous shunt with vitrectomy in malignant glaucoma. Arch Ophthalmol 1998; 116:808-810
4. Harbour JW, Rubsamen PE, Palmberg P. Pars plana vitrectomy in the management of phakic and pseudophakic malignant glaucoma. Arch Ophthalmol 1996; 114:1073-1078
5. Byrnes GA, Leen MM, Wong TP, Benson WE. Vitrectomy for ciliary block (malignant) glaucoma. Ophthalmology 1995; 102:1308-1311
6. Lynch MG, Brown RH, Michels RG, et al. Surgical vitrectomy for pseudophakic malignant glaucoma. Am J Ophthalmol 1986; 102:149-153
© 2004 by Lippincott Williams & Wilkins, Inc.