Malignant Glaucoma

Malignant Glaucoma

Background

In 1869, von Graefe first used the term malignant glaucoma to describe an entity characterized by elevated intraocular pressure (IOP) with a shallow or flat anterior chamber in the presence of a patent peripheral iridectomy. In its classic form, malignant glaucoma is rare but one of the most serious complications of glaucoma filtration surgery in patients with narrow-angle or angle-closure glaucoma.

The term malignant glaucoma refers to a sustained ongoing process that is difficult to treat and characteristically progresses to blindness. It is sometimes unresponsive and occasionally worsened with conventional management.

Many different terms, including ciliovitreal block and aqueous misdirection syndrome, have been proposed based on diverse unproven pathophysiological and anatomical mechanisms. In the international literature, a common term used to describe a flat anterior chamber is "athalamia." However, it seems appropriate to continue using well-established nomenclature.

Pathophysiology

A blockage of the normal aqueous flow at the level of the ciliary body, lens, and anterior vitreous face is believed to cause malignant glaucoma. Posterior misdirection of aqueous humor into the vitreous cavity occurs producing a continuous expansion of the vitreous cavity and increased posterior segment pressure. This accumulation of aqueous fluid in the vitreous cavity causes anterior displacement of the lens-iris diaphragm in phakic and pseudophakic eyes or forward displacement of the anterior hyaloid in aphakic patients. The resulting shallow or flat chamber is believed to exacerbate the condition because of the decreased access of aqueous to the trabecular meshwork. The IOP is often markedly increased but may be normal.

Epstein et al proposed that forward displacement of the vitreous into apposition with the posterior ciliary body caused a decrease in available hyaloid surface, increasing the resistance to flow from the vitreous body. Small hyperopic eyes are at higher risk for malignant glaucoma.

Malignant glaucoma has been described following: cataract surgery with or without intraocular implant (aphakic or pseudophakic malignant glaucoma), implantation of a large posterior chamber intraocular lens, cessation of topical cycloplegic therapy, induction of miotic therapy, laser iridotomy, laser capsulotomy, Nd:YAG cyclophotocoagulation, laser sclerotomy, Molteno implantation, Baerveldt glaucoma drainage device implantation, viscoelastic use, intravitreal injection of triamcinolone acetonide, Aspergillus flavus intraocular infection, and acute hydrops in Down syndrome. Malignant glaucoma has also been described spontaneously in an eye with no antecedent of surgery or miotics. A pseudomalignant glaucoma syndrome has been reported after pars plana vitrectomy.

Frequency

United States

Malignant glaucoma has been reported to occur in 0.6-4% of eyes following filtration surgery for angle-closure glaucoma. Trope et al reported that 71% of 14 patients with malignant glaucoma had chronic angle-closure glaucoma. Malignant glaucoma also can be a rare complication of extracapsular cataract extraction with posterior chamber intraocular lens implantation.

International

In Germany, Duy and Wollensak reported 2 cases of ciliary block in 9000 patients following cataract extraction. However, both patients had previous filtration procedures with temporary shallowing of the anterior chamber postoperatively.

Mortality/Morbidity

Malignant glaucoma remains a difficult clinical problem that results in irreversible blindness if not promptly treated. The surgeon should be aware preoperatively of eyes at risk and observe them closely postoperatively. Early recognition is the most important step to prevent irreversible vision loss.

Age

Trope et al reported that the average age of patients with malignant glaucoma was 70 years.

Clinical

History

Typically, patients with narrow-angle or acute or chronic angle-closure glaucoma, who recently underwent filtration surgery, present shortly after surgery; however, it can develop months later or even in the absence of surgery.

• Patients may present with pain and discomfort, increasing redness, blurring, or decreased visual acuity.
• Pain may be severe enough to cause nausea and induce vomiting, similar to an attack of acute angle-closure glaucoma.
• Precipitating factors are suture lysis, initiation of miotic therapy, or discontinuation of cycloplegics.
• Shallowing of the anterior chamber due to wound leak must be ruled out by performing a Seidel test during slit lamp examination.

Physical

• In malignant glaucoma, slit lamp examination reveals anterior displacement of the lens-iris diaphragm in phakic patients and the anterior hyaloid face in aphakic patients, shallowing of the central and peripheral anterior chamber, and elevated intraocular pressure with a patent iridectomy present.
• Optically clear spaces can be observed within the vitreous cavity and have been interpreted as pockets of fluid.
• With the Goldman lens, a completely closed angle can be observed. Choroidal detachments or suprachoroidal hemorrhage should be ruled out using the goniolens mirrors and indirect ophthalmoscopy. The retina should be evaluated for vascular occlusions, and the vitreous should be evaluated for possible hemorrhages. B-mode ultrasound can be extremely useful if direct visualization is not possible.
• Malignant glaucoma is not caused by pupillary block where laser iridotomy can relieve the flow obstruction. In malignant glaucoma, a patent iridectomy must be demonstrated. If not, a new laser iridotomy must be performed.
• Ultrasound biomicroscopy has demonstrated anterior rotation of the ciliary body with apposition to the ciliary process in contact with the lens equator and anterior displacement of the ciliary body and lens, causing iridocorneal touch and appositional angle closure in these patients.

Causes

The exact mechanism that leads to malignant glaucoma is not clearly understood. Movement of aqueous humor from the posterior chamber into the vitreous instead of draining to the anterior chamber may be the cause.

• Malignant glaucoma may occur within hours to days or years after surgery. Most commonly, it is seen after trabeculectomy or surgical iridectomy. This condition may be noted after the cessation of cycloplegic drops or the initiation of miotic therapy after surgery for angle-closure glaucoma.
• The fellow eye is predisposed strongly to develop malignant glaucoma.
• In 1954, Shaffer proposed that misdirection of aqueous humor into the vitreous body or around it was the pathogenic mechanism.
• In 1972, Levene suggested that malignant glaucoma results from forward movement of the lens with direct closure of the angle intensified by surgery, and it represents a more severe form of angle-closure glaucoma. The tone of the ciliary body muscle and the tension of the zonules could explain the anterior movement of the lens.
• Epstein et al hypothesized that a sustained expansion in total vitreous volume moves available peripheral anterior hyaloid into apposition with the posterior ciliary body increasing the resistance for anterior fluid transfer and causing forward displacement of the lens-iris diaphragm and shallowing of the anterior chamber.
• In 1980, Quigley incorporated data from Fatt into this theory and proposed that dehydrated and compressed vitreous with a decreased fluid conductivity establishes a vicious circle of elevated pressure and anterior chamber shallowing.

Differential Diagnoses

Choroidal Detachment

Pupillary Block, Aphakic

Pupillary Block, Pseudophakic

Other Problems to Be Considered

Suprachoroidal hemorrhage

Overfiltration

Wound leak

Occult annular ciliary body detachment

Workup

Imaging Studies

• A-mode ultrasound is used to measure axial length.
• B-mode ultrasound can discover occult choroidal effusions or hemorrhages or vitreous hemorrhage.
• Ultrasound biomicroscopy (UBM) is used to obtain cross-sectional images of the anterior segment, cornea, iris, lens, and ciliary body at 50 µm resolution with a tissue penetration of 5 mm.

Procedures

• Bleb or wound leaks should be identified and treated first.
• Because of its simplicity, a new laser iridotomy should be performed if suspicion of pupillary block exists.

Treatments for Malignant glaucoma

The list of treatments mentioned in various sources for Malignant glaucoma includes the following list. Always seek professional medical advice about any treatment or change in treatment plans.

• Cycloplegic agents
• Topical phenylephrine
• Topical beta-blockers
• Alpha-adrenergic agonists
• Topical and oral carbonic anhydrase inhibitors
• Osmotic agents
• Argon or Yag laser
• Pars plana vitrectomy

Prognosis for Malignant glaucoma

Prognosis for Malignant glaucoma: The prognosis depends on the length and the severity of the attack. In patients with relatively healthy optic nerves, the prognosis can be good if the attack is abated and intraocular pressure is controlled.