Signs and Symptoms
Malignant glaucoma, also referred to as aqueous misdirection syndrome or ciliary block glaucoma, occurs without racial or gender predilection.1-6 Patients typically have hyperopic and small (nanophthalmic) eyes. Most significantly, there is a history of antecedent ocular surgery (typically, glaucoma surgery) with complications beginning shortly after. Malignant glaucoma occurs most commonly after trabeculectomy, glaucoma drainage device implantation, peripheral iridectomy or iridotomy, and cataract surgery.1-6 Frequently, there may have been a period of hypotony due to over-filtration following glaucoma surgery. Initially, malignant glaucoma may present with statistically normal, though rising, intraocular pressure (IOP) with concurrent anterior chamber shallowing.1,7
Biomicroscopically, there will be a shallow or flat anterior chamber in the presence of an intact iridectomy or iridotomy.8-10 Frequently, there is a preoperative history of anatomically narrow angles, as well as prior miotic therapy.9 For instance, plateau iris syndrome, which is often medically treated with miotics, may predispose such patients to postoperative malignant glaucoma.11 Patients who develop significant inflammation, such as that seen with scleritis, may also develop malignant glaucoma. Trauma, retinal detachment surgery, panretinal photocoagulation and central retinal vein occlusion have also been reported in association with the development of malignant glaucoma.12
Progressive flattening of the anterior chamber following surgery, with progressive IOP rise, is the hallmark of malignant glaucoma.9 Further, there will be no iris bombé or evidence of supraciliary effusion.1,9,13,14 Should IOP elevate abruptly, classic signs and symptoms similar to those seen in acute angle-closure glaucoma may occur.
Malignant glaucoma is actually an imprecise description, as there is no malignancy associated with the condition. The term was introduced because the condition was historically poorly understood, difficult to treat and often resulted in significant visual morbidity. Likewise, aqueous misdirection syndrome is also a misnomer in that it is not universally accepted that the aqueous is actually misdirected in every case.9,13-15
The ciliary body in eyes with malignant glaucoma tends to be thinner and more anteriorly rotated.16 An accepted theory holds that the ciliary body and ciliary processes form a tight apposition to the peripheral lens as well as to the anterior vitreous—this may occur following ocular surgery, through a natural predisposition or, paradoxically, following a period of hypotony. It prevents the aqueous from flowing into the anterior chamber. Subsequently, the aqueous is diverted into the vitreous cavity, increasing its volume.
An abnormally impermeable anterior hyaloid face may play a role by preventing aqueous from diffusing through the vitreous into the anterior chamber, thus causing an increase in the volume of the vitreous. This expansion of the vitreous secondarily pushes the lens and iris towards the cornea with subsequent shallowing and flattening of the anterior chamber and closure of the angle.
The classic appearance is that of a shallow anterior chamber axial depth (lens-cornea distance) along with an accompanying shallow peripheral anterior chamber depth (iris-cornea distance).1,15,17 In contradistinction, a patient with acute pupil-block primary angle closure will have a normal axial depth and a shallow peripheral depth. In pupil-block glaucoma, a peripheral iridotomy will lead to deepening of the chamber; however, iridotomy has no effect in malignant glaucoma. The hallmark is a closed angle with a shallow chamber, no plateau iris configuration and narrow axial depth that remains despite patent iridotomy or iridectomy.
Intervention begins medically, with the goal of breaking the apposition of the ciliary body and processes to the lens (in phakic situations) and/or anterior vitreous in aphakic situations. This is accomplished by relaxing the ciliary body and lens zonules using a potent cycloplegic such as atropine, allowing the lens to release posteriorly.1,7,18
Aqueous suppressants can be used to temporize the intraocular pressure and topical steroids to ameliorate any inflammation. Miotics are contraindicated, as they can precipitate or worsen the condition. Oral carbonic anhydrase inhibitors and hyperosmotic agents can be used to dehydrate and shrink the vitreous.
Medical control is effective in a moderate number of cases and represents the safest first option.1,15 Medical therapy appears to be most effective in phakic eyes, while pseudophakic eyes and refractory cases require a step-wise surgical approach.19
Should medical control not be effective, surgical options must be employed. Relieving malignant glaucoma and aqueous misdirection caused by increased resistance to aqueous flow anteriorly through the ciliary body/zonules/lens capsule complex requires the establishment of a conduit to allow fluid passage.20
The first of the surgical options is hyaloidotomy, which is designed to disrupt the anterior hyaloid face of the vitreous and allow aqueous to escape from the ballooning vitreous cavity. This option attempts to redirect aqueous into the anterior chamber rather than the posterior chamber. The most common method involves Nd:YAG laser photodisruption of the anterior vitreous face through an iridectomy or iridotomy hole or through the pupil. Once accomplished, the pre-existing opening may then serve as the conduit for aqueous to reach the anterior chamber.1,9
A more invasive method of surgically correcting malignant glaucoma is through core vitrectomy.20-23 Here, the anterior vitreous is “debulked,” giving the iris a chance to relax and the anterior chamber to deepen. Further, pockets of aqueous within the vitreous are removed and the anterior vitreous face is disrupted, potentially removing the blockage that prevented the aqueous from ultimately getting through the pupil.
All surgical options are designed to establish a communication between the vitreous cavity and anterior chamber.22,23 Diode laser cyclodestruction has been used as a complementary treatment in managing the IOP in cases of refractory malignant glaucoma.2,24
More recently, several procedures used in combination have been seen as successful. One combination includes partial pars plana vitrectomy, hyaloido-zonulectomy and peripheral iridectomy.25 Combined phacoemulsification/IOL implantation/posterior capsulorhexis/anterior vitrectomy surgery is considered a safe and effective method for treating patients with phakic malignant glaucoma.26 The necessary combination of multiple procedures to effect a surgical cure seems to underscore a poor overall understanding of the exact pathogenesis of malignant glaucoma.
Unfortunately, even after successful treatment of malignant glaucoma, the angle may remain closed due to extensive peripheral anterior synechiae. If more than half of the angle remains closed, IOP will remain permanently elevated despite successful treatment of the underlying cause. In this case, the surgeon may try to break the peripheral anterior synechiae with a goniosynechialysis, or the patient may require some form of permanent medical therapy.
• Pupillary block is the most common condition mimicking malignant glaucoma. Laser iridotomy will relieve pupil block angle closure but will have no effect on malignant glaucoma. However, laser iridotomy must be done to help differentiate the two conditions.
• Choroidal effusion with a shallow anterior chamber, particularly after glaucoma filtration surgery, is the second most common differential diagnosis for malignant glaucoma. Large effusions will be seen ophthalmoscopically. Small suprachoroidal effusion can cause an anterior rotation of the ciliary body and precipitate this condition. Small effusions are typically only detected with the use of ultrasound biomicroscopy.
• After glaucoma surgery, such as trabeculectomy, a flat anterior chamber and low IOP is suggestive of either over-filtration or bleb leakage. If the anterior chamber is flattening and shallowing while the IOP is rising, malignant glaucoma should be considered the cause.
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11. Prata TS, Dorairaj S, De Moraes CG, et al. Is preoperative ciliary body and iris anatomical configuration a predictor of malignant glaucoma development? Clin Experiment Ophthalmol. 2013;41(6):541-5.
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16. Wang Z, Huang J, Lin J,et al. Quantitative Measurements of the Ciliary Body in Eyes with Malignant Glaucoma after Trabeculectomy Using Ultrasound Biomicroscopy. Ophthalmology. 2013 Dec 6. pii: S0161-6420(13)01041-5. doi: 10.1016/j.ophtha.2013.10.035. [Epub ahead of print]
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18. Zhang WZ, Huang L, Ma J, et al. Retrospective clinical analysis of 118 cases with malignant glaucoma. Zhonghua Yan Ke Za Zhi. 2013;49(2):126-9
19. Dave P, Senthil S, Rao HL, Garudadri CS. Treatment outcomes in malignant glaucoma. Ophthalmology. 2013 May;120(5):984-90.
20. Sharma A, Sii F, Shah P, et al. Vitrectomy-phacoemulsification-vitrectomy for the management of aqueous misdirection syndromes in phakic eyes. Ophthalmology. 2006;113(11):1968-73.
21. Byrnes GA, Leen MM, Wong TP, et al. Vitrectomy for ciliary block (malignant) glaucoma. Ophthalmology. 1995;102(9):1308-11.
22. Chaudhry NA, Flynn HW Jr, Murray TG, et al. Pars plana vitrectomy during cataract surgery for prevention of aqueous misdirection in high-risk fellow eyes. Am J Ophthalmol. 2000;129(3):387-8.
23. Sharma A, Sii F, Shah P, et al. Vitrectomy-phacoemulsification-vitrectomy for the management of aqueous misdirection syndromes in phakic eyes. Ophthalmology. 2006;113(11):1968-73.
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26. Liu X, Li M, Cheng B, et al. Phacoemulsification combined with posterior capsulorhexis and anterior vitrectomy in the management of malignant glaucoma in phakic eyes. Acta Ophthalmol. 2013;91(7):660-5.