rarely recognized. Ronald L. Fellman, MD, describes its diagnostic features and management considerations.
Malignant glaucoma is a type of angle-closure glaucoma that is uncommon and therefore rarely recognized. Ronald L. Fellman, MD, describes its diagnostic features and management considerations.
By Cheryl Guttman Krader; Reviewed by Ronald L. Fellman, MD
Dallas-Malignant glaucoma is a rare condition, and so ophthalmologists can go for decades without encountering a single case of this angle-closure glaucoma. Or-because the condition is so uncommon-clinicians who do not maintain an index of suspicion for malignant glaucoma may overlook the diagnosis and mistake it as pupil block, according to Ronald L. Fellman, MD.
Differentiating the two conditions is important, because their treatment is different and can be easily done by careful examination at the slit lamp, said Dr. Fellman, attending surgeon and clinician at Glaucoma Associates of Texas, Dallas.
“Malignant glaucoma is angle-closure glaucoma in which there is ciliovitreal block-not pupil block-although the two may co-exist,” Dr. Fellman said. “Understanding the anatomic features along with clinical suspicion of malignant glaucoma is the key to both its accurate recognition and appropriate treatment.”
Although the pathogenic mechanism for malignant glaucoma remains unclear, there is no question that the angle closure is associated with anterior displacement of both the iris and lens. On slit lamp examination, therefore, the giveaway diagnostic clue is axial shallowing with anterior displacement of the lens-iris diaphragm.
In contrast, only the iris will be bowed forward toward the cornea when angle closure is due to pupil block, Dr. Fellman explained.
“Patients with malignant glaucoma may also have a history of narrow angles and pupil block, and so many of them already have a patent iridotomy,” he said. “IOP may be elevated, but it may be normal.”
Other findings in eyes with malignant glaucoma include a normal-appearing posterior segment-i.e., there is no suprachoroidal hemorrhage, central retinal vein occlusion, or choroidal mass to explain the axial shallowing. Typically, malignant glaucoma develops in short eyes that have a thick sclera, and often, the patient has a recent history of intraocular surgery (e.g., cataract or glaucoma surgery) that may be the precipitating event.
Various theories have been proposed to explain the development of malignant glaucoma. However, Dr. Fellman said that a concept introduced by Harry Quigley, MD, in his 2009 Edward Jackson Memorial Lecture seems to make the most sense.
According to Dr. Quigley, the triggering event is expansion of the choroid. Subsequently, a pressure differential across the vitreous gel is created that decreases its fluid conductivity and results in increased vitreous compression. As the vitreous gel moves forward, it crowds the ciliary body and lens, aggravating a relative ciliovitreal block with further axial collapse of the anterior chamber. As the IOP increases, the cycle worsens.
Medical management should be prescribed as initial treatment for malignant glaucoma. It is effective in relieving the angle-closure attack about 50% of the time and involves a multipronged approach.
The medical regimen includes a mydriatic cycloplegic agent that decreases ciliovitreal block by multiple mechanisms that include:
· Tightening the zonules, which retracts the lens
· Widening the ciliary body diameter, which allows for better aqueous diffusion
· Pulling the ciliary body processes away from the lens equator, which also improves aqueous diffusion.
Also, if the physician suspects simultaneous pupillary block, adding a sympathomimetic may further alleviate it.
In addition, an aqueous suppressant agent is used to reduce IOP, reducing the trans pressure differential across the vitreous gel, and patients are treated with a hyperosmotic agent as well that shrinks the vitreous and choroid.
If medical management fails, surgery is indicated. Its goal is to create a unichambered eye, and whether the patient is phakic or pseudophakic, surgery should include iridozonulohyaloidotomy plus pars plana vitrectomy (PPV). Phacoemulsification may be necessary in phakic eyes.
“Timely surgical treatment breaks the ciliovitreal block and saves the angle,” Dr. Fellman said.
“In the past, PPV alone was performed to treat malignant glaucoma, but it did not always relieve the ciliovitreal-hyaloid block because in malignant glaucoma, the problem does not involve the vitreous alone,” he said. “Adding iridozonulohyaloidotomy to create a unichambered eye breaks the angle-closure attack because it gives aqueous access to all chambers.”
Dr. Fellman noted that considering the connotation of the word “malignant,” ophthalmologists may consider referring to the condition as aqueous misdirection syndrome, or preferably ciliovitreal block, in their discussions with patients.
Clinicians should also recognize that patients who develop malignant glaucoma in one eye are at risk for developing the condition in the fellow eye.
Ronald L. Fellman, MD
This article was adapted from Dr. Fellman’s presentation during Glaucoma Day at the 2014 meeting of the American Society of Cataract and Refractive Surgery. Dr. Fellman has no financial conflicts with the subject matter.