November 2018

GLAUCOMA

Presentation spotlight
Diagnostic and therapeutic challenge: malignant glaucoma


by Stefanie Petrou Binder, MD, EyeWorld Contributing Writer

“For the management of malignant glaucoma, we can propose the following: medical, then Nd:YAG laser, and finally surgical.”
—Oifa Fekih, MD

 

Thorough patient screening and timely intervention are critical to avoid malignant glaucoma

Malignant glaucoma is described as a condition characterized by elevated or normal IOP with a shallowing or flattening of the central and peripheral parts of the anterior chamber (AC), usually occurring after ocular surgery, in eyes without pupillary block or posterior segment pathology. It has also been referred to as aqueous misdirection, ciliary block glaucoma, and lens block angle closure.
In a presentation given at the 2018 World Ophthalmology Congress, Oifa Fekih, MD, Glaucoma Center, Tunis, Tunisia, shared her expertise on this rare complication, seen in 0.4–6% of glaucoma patients. “The European Glaucoma Society defines malignant glaucoma as secondary angle closure glaucoma with a posterior pushing mechanism caused by the forward rotation of the ciliary body and iris. It is a challenging problem when encountered,” she said.

First hurdle: Diagnosis

According to Dr. Fekih, the first step in the management of this pathology is making an empiric diagnosis. Malignant glaucoma has been known to occur in eyes with axial hyperopia, nanophthalmos, plateau iris configuration, and is usually encountered after glaucoma surgery for primary angle closure glaucoma (PACG). Other associations have been post-laser treatment, cataract surgery or penetrating keratoplasty, trabeculectomy bleb needling, spontaneously by way of infection, retinal vein occlusion, or retinopathy of prematurity. Many cases of malignant glaucoma are associated with the fellow eye.
“Often there is a rise in IOP,” Dr. Fekih explained. “The diagnosis can include: flattening of the anterior chamber, iridocorneal touch, appositional angle closure, and apposition of the iris. The patient examination can be difficult especially when doing UBM or anterior segment OCT, which is used for diagnosis and for treatment monitoring. These imaging techniques allow us to explore the structures surrounding the posterior chamber and visualize the anterior rotation of the ciliary body that is characteristic of this pathology, which is helpful for the differential diagnosis. There are three entities that should be ruled out: pupillary block, suprachoroidal hemorrhage, and choroid effusion. Once the diagnosis is made, it is important to understand the mechanism of malignant glaucoma because we are not talking about one disease but a multifactorial condition. The exact etiology, however, has not yet been understood,” she said.
Three mechanisms have been proposed in the etiology of malignant glaucoma. One theory proposes that aqueous humor is directed posteriorly into the posterior segment. The diversion of aqueous flow into the posterior segment comes from an abnormal relationship between the ciliary body process, lens, and anterior vitreous.1 Another theory attributes the forward lens movement seen in this condition to laxity of the lens zonules. A final notion rejects the idea of aqueous misdirection and proposes that choroidal expansion is the trigger that increases vitreous pressure and leads to the shallowing of the anterior chamber.
“Whatever the cause, the final common pathway is a vicious cycle of the transvitreal pressure increasing, poor conductivity of the vitreous that creates a ciliary blockage and trapping of aqueous humor, which leads to a shallowing of the anterior chamber and an increase in IOP, which will further aggravate the vicious cycle. The aim of any treatment is to break the vicious cycle and restore normal aqueous flow,” Dr. Fekih explained.

Second hurdle: Treatment

Medical therapy, laser therapy, and surgical management are all options for the treatment of malignant glaucoma. The medical approach includes mydriatic and cycloplegic agents to relax the ciliary muscle and tighten the lens zonules, giving a posterior push to the iris and crystalline lens diaphragms. Dr. Fekih combines this with acetazolamide, topical beta blockers, and osmotic agents to reduce the production of aqueous and the vitreous volume. This can help to deepen the anterior chamber and possibly increase vitreous permeability. She recommends this treatment be tried for 3–5 days before turning to other alternatives.
Laser therapy is the second line of treatment. Nd:YAG laser is used to rupture the posterior capsule and the anterior hyaloid membrane, in both pseudophakic and phakic eyes. This releases the trapped aqueous from the vitreous and allows it to resume movement between the posterior and anterior segments. Dr. Fekih also lasers the ciliary processes with transpupillary argon laser photocoagulation and cyclocryotherapy. Transscleral cyclodiode lasers help to eliminate vitreous blockage by allowing the posterior rotation of the ciliary process, however, by shrinking the ciliary process it can also induce aqueous humor production, she noted.
The surgical approach involves an anterior vitrectomy, phacoemulsification, and an iridectomy/hyaloido/zonulectomy, in both phakic and pseudophakic eyes with malignant glaucoma, which has been met with a 65% success rate. “This process is called vitrectomy/phacoemulsification/vitrectomy for the management of aqueous misdirection syndromes in phakic eyes,” Dr. Fekih said. “The first step is a partial vitrectomy to unblock the vitreous and soften the eye and deepen the anterior chamber. This is followed by phaco. Lens removal is important in phakic patients with malignant glaucoma because lens extraction and the effective removal of the anterior hyaloid create space, and the artificial IOL is much thinner than the crystalline lens. It is also recommended to cut the posterior capsule in the center. The last step is to complete the core vitrectomy. In severe cases, a complete pars plana vitrectomy is indicated.”
A review of the literature reveals that surgical treatment allows patent communication between the vitreous cavity and the anterior chamber. Compared with other modalities, surgery, especially, compete vitrectomy with phaco and zonulo-hyaloidectomy, is the most successful modality, when compared to laser and medical treatments. A complete vitrectomy combined with iridectomy and zonulectomy (and phacoemulsification, if applicable) was seen in a study of 24 eyes in 21 patients with malignant glaucoma to most successfully manage aqueous misdirection syndrome.2 Once the AC deepens and IOP has been normalized, medical treatment can be withdrawn gradually. The patient may require indefinite treatment with cycloplegics to prevent recurrence if vitrectomy was not performed.3

Avoiding malignant glaucoma

“Screening predisposing eyes, use of prophylactic perioperative measures like avoiding myotic drugs and the prolonged use of atropine after trabeculectomy, placing laser peripheral iridotomies, using transscleral diode before surgery, avoiding anterior chamber shallowing with viscoelastics, tight scleral flap suturing, adjustable sutures, and performing lens extraction are all steps to take to avoid malignant glaucoma,” Dr. Fekih said. “For a phakic patient with PACG, lens extraction should be the primary procedure, even before trabeculectomy, because there is a lower risk of malignant glaucoma after cataract surgery and it is easier to manage the condition in pseudophakic eyes. Finally, prophylactic vitrectomy combined with phacoemulsification is indicated when there is a history of malignant glaucoma in the fellow eye. For the management of malignant glaucoma, we can propose the following: medical, then Nd:YAG laser, and finally surgical. Surgical treatment is indicated when medical treatment fails,” she said.

References

1. Wong MMY, et al. Aqueous misdirection. EyeWiki.
2. Debrouwere V, et al. Outcomes of different management options for malignant glaucoma: a retrospective study. Graefes Arch Clin Exp Ophthalmol. 2012;250:131–41.
3. Dorairaj S, et al. Diagnosis and management of malignant glaucoma. EyeNet. American Academy of Ophthalmology. April 2010.

Editors’ note: Dr. Fekih has no financial interests related to her comments.

Contact information

Fekih: olfa.fekih@gmail.com

Diagnostic and therapeutic challenge: malignant glaucoma Diagnostic and therapeutic challenge: malignant glaucoma
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