Two cases of malignant glaucoma unresolved by pars plana vitrectomy
Yoshikatsu Hosoda, Tadamichi Akagi, Nagahisa Yoshimura
Department of Ophthalmology and Visual Sciences, Kyoto University Graduate School of Medicine, Kyoto, Japan
Abstract: Malignant glaucoma, which is characterized by a shallow or flat anterior chamber with high intraocular pressure, can usually be resolved by pars plana vitrectomy with anterior hyaloidectomy. We describe two cases in which malignant glaucoma was refractory to conventional treatment and complete vitrectomy. Case one an 88-year-old woman with pseudoexfoliation glaucoma underwent trabeculotomy and subsequently developed malignant glaucoma. Four months after transient recovery by pars plana vitrectomy, the malignant glaucoma recurred. She underwent peripheral iridectomy and local zonulectomy with successful control of her intraocular pressure. In case two, an 85-year-old man had a history of pseudoexfoliation glaucoma. Seven months after phacoemulsification and intraocular lens implantation, he developed malignant glaucoma that was refractory to pars plana vitrectomy. He underwent peripheral iridectomy, goniosynechialysis and trabectome surgery resulting in the successful control of his intraocular pressure. In rare cases of malignant glaucoma refractive to vitrectomy, peripheral iridectomy with or without local zonulectomy is a reasonable and minimally invasive surgical procedure.
Keywords: malignant glaucoma, pars plana vitrectomy, peripheral iridectomy
Malignant glaucoma was first described by Von Graefe in 1869.1 It is a rare postoperative complication characterized by a flattening of the anterior chamber and elevated intraocular pressure (IOP), and is also known as ciliary block glaucoma or aqueous misdirection. Various medical, laser-based, and surgical treatments for malignant glaucoma have been reported in the literature.2 Although medical treatment such as topical cycloplegics, topical aqueous suppressants, oral carbonic anhydrase inhibitors, and systemic hyperosmotic agents, should be considered first, it is not effective solely in approximately 50% of malignant glaucoma cases.3 Other treatment options include neodymium-doped yttrium aluminum garnet (Nd:YAG) laser capsulohyaloidotomy or surgical disruption of the anterior hyaloid. In cases that are refractory to the aforementioned treatment options, pars plana vitrectomy (PPV) with or without lensectomy can be used.4 Diode laser cyclophotocoagulation would be another option in cases that are refractory to all other treatments.
Here, we report two rare cases in which malignant glaucoma was refractory to conventional treatment and complete vitrectomy. At 4 and 1 month, respectively, after PPV, malignant glaucoma recurred and the patients underwent peripheral iridectomy which resulted in successful control of their IOP.
Case one was an 88-year-old woman with a history of pseudoexfoliation glaucoma in the right eye (OD) with maximum IOP >30 mmHg. Both eyes were pseudophakic and showed normal anterior chamber depth. Because her IOP OD could not be controlled with additional glaucoma eyedrops and oral acetazolamide, she underwent trabeculotomy. Three days after the trabeculotomy, she developed a flattening of the anterior chamber and an elevated IOP OD. She was diagnosed with malignant glaucoma. The condition could not be resolved with systemic hyperosmotic agents and oral carbonic anhydrase inhibitors, so she underwent an emergent PPV (total vitrectomy) using a 25 gauge vitreous cutter with vitreous base shaving and removal of the anterior hyaloid. Her anterior chamber deepened, and her IOP decreased to 10 mmHg the following day. Her IOP was maintained in the mid-teens OD by using three types of glaucoma eyedrops. Four months after PPV, her IOP increased to 70 mmHg again with a flat anterior chamber (Figure 1A, B). We hypothesize that the cilio-pupillary block mechanism was related to her clinical condition, and we performed an emergent iridectomy and local zonulectomy using a 25 gauge vitreous cutter. The posterior synechia of the iris was partially, but not completely, observed intraoperatively. Her anterior chamber had deepened (Figure 1C, D); for 10 months, her IOP has been maintained in the low-teens OD with the use of two types of glaucoma eyedrops.
Case two was an 85-year-old man with a history of primary angle closure in both eyes (OU) and pseudoexfoliation glaucoma OD. He underwent phacoemulsification and aspiration (PEA), and intraocular lens (IOL) implantation OU. Following cataract surgery, he frequently exhibited a flattening of the anterior chamber and elevated IOP of >40 mmHg on maximal glaucoma medications. As his clinical condition OD was considered to be related to the malignant glaucoma mechanism, he underwent a YAG capsulohyaloidotomy and goniosynechialysis (GSL) for severe peripheral anterior synechia (PAS). Ten months after cataract surgery, his IOP OD was 32 mmHg, and his anterior chamber was still very shallow. He then underwent PPV (total vitrectomy) using a 25 gauge vitreous cutter with vitreous base shaving and removal of the anterior hyaloid, and GSL OD, at which point his anterior chamber deepened significantly and his IOP decreased to the low-teens. One month after PPV, he once again exhibited a flattening of the anterior chamber and severe PAS, and was referred to Kyoto University Hospital (Figure 2A, B). He presented with spontaneous IOL dislocation within the capsular bag. His IOP OD increased to 32 mmHg, and his visual acuity worsened to counting finger vision. He underwent an iridectomy without zonulectomy using a 25 gauge vitreous cutter near the area where Zinn’s zonule had been partially ruptured. We further performed GSL and trabectome surgery (NeoMedix Corporation, Tustin, CA, USA) (a surgical procedure that ablates an arc of trabecular meshwork). His anterior chamber had deepened (Figure 2C, D); for 6 months, his IOP has been maintained in the high-teens OD by using additional glaucoma eyedrops.
PPV has been considered to be efficacious in the treatment of pseudophakic malignant glaucoma.5 It is important to perform total vitrectomy with surgical disruption of the anterior hyaloid to break the primary mechanism of aqueous misdirection. However, it was previously reported that patients experienced recurrence of malignant glaucoma following vitrectomy, which is also called malignant glaucoma-like syndrome.6,7 In such cases, the flattening of anterior chamber spaces and the elevation of IOP are caused by hydration of the vitreous cavity, not the vitreous. Our two cases showed the cilio-pupillary block caused by the forward movement of the IOL due to a weak or partially ruptured zonular apparatus and dislocated IOL. It has been shown8 that malignant glaucoma is more common in females due to the lens being in a more forward position, and shallower anterior chamber, although, in our cases, one patient was female and the other male. Our cases both presented with pseudoexfoliation syndrome, which could be a risk factor for malignant glaucoma due to its weak zonule and possibility of rupture. In case one, partial posterior synechia of the iris was observed during surgery; thus, it is possible that partial posterior synechia and anterior dislocated IOL caused the cilio-pupillary block. As the patient’s PAS was not severe, the IOP could be controlled adequately with peripheral iridectomy and local zonulectomy alone. In case two, total posterior synechia of the iris was identified intraoperatively, and the cilio-pupillary block caused by the posterior synechia of the iris was presumed to have caused the elevated IOP. Because peripheral iridectomy alone seemed to be insufficient to reduce the IOP for over 90% PAS of the angle circumference, the patient underwent GSL, trabectome surgery, and patent peripheral iridectomy. The benefit of trabectome surgery is its availability in the operative field, similar to GSL, and its efficacy in treating possible functional disorders of the trabecular meshwork. In case two, local zonulectomy was not performed because the Zinn’s zonule had been partially ruptured.
Our two cases demonstrate a recurrence of malignant glaucoma following PPV. It has been reported that hyaloid-zonulectomy and iridectomy are effective in treating aqueous misdirection.9 We also suggest that patent peripheral iridectomy with, or without local zonulectomy is an effective surgical procedure in the prevention of prospective ciliary, or pupillary blockage, regardless of whether the patient has previously undergone any type of vitrectomy to treat malignant glaucoma in cases of a weak zonular apparatus, dislocated IOL, or severe posterior synechia. In cases of severe PAS, a combined procedure, including the reconstruction of the trabecular meshwork with such procedures as GSL and trabectome surgery, may also be an effective treatment, as we demonstrated. In conclusion, peripheral iridectomy is a appropriate and minimally invasive surgical procedure used to break the cycle of malignant glaucoma refractive to conventional treatments and PPV.
The authors report no conflicts of interest in this work.
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