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Increased IOP After Glaucoma Treatment
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A 34-year-old woman presented with increased IOP in the right eye. She had juvenile-onset open-angle glaucoma and bilateral trabeculectomies more than 10 years earlier. She was on maximal medical therapy and had previous needling of the bleb.
Her vision was 20/25 in both eyes, with IOP 25 mm Hg in the right and 15 mm Hg in the left. Pachymetry showed a central corneal thickness of 580 µm in the right eye and 531 µm in the left. The bleb was elevated but encapsulated in the right eye. The lens was normal. Gonioscopy showed broad peripheral anterior synechiae in both eyes with mostly closed anterior chamber angles. Fundus examination showed a large cup in both eyes, with a thin temporal neural rim. Automated perimetry showed a large superior and inferior nasal defect in the right eye.
The patient presented after fi ltration surgery
with a shallow chamber and markedly elevated
IOP that was not responding to initial
treatment with cycloplegia laser.
Source: Peter A. Netland, MD, PhD
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here
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The right eye was treated with an Ahmed Glaucoma Valve (New World Medical). On postoperative day 1, the IOP was 10 mm Hg, and the anterior chamber was deep. The next day, the anterior chamber was shallow with an IOP of 18 mm Hg. Despite treatment with cycloplegia and laser therapy through the iridectomy, the IOP increased to 50 mm Hg with a flat anterior chamber.
Diagnosis
This patient has malignant glaucoma, named for its progressive course and poor response to conventional treatment. The condition is believed to evolve from posterior misdirection of aqueous humor into or behind the vitreous. The resulting pressure differential between posterior and anterior chambers causes an anterior displacement of the lens-iris diaphragm, anterior chamber shallowing and secondary angle-closure. No theory has established a single cause of the condition.
Malignant glaucoma is uncommon and is usually seen after incisional surgery, particularly glaucoma surgery in eyes with prior angle closure, with a reported incidence of 2% to 4%.1 However, the condition may occur after any intraocular procedure—or spontaneously in previously unoperated eyes.2,3 Differential diagnoses include pupillary-block glaucoma, choroidal detachment, suprachoroidal hemorrhage, and wound leak or overfiltration.
After pars plana vitrectomy, the anterior chamber was deep and IOP normalized.
Source: Peter A. Netland, MD, PhD
Click
here
for a larger view of this image.
Treatment
On day 8 after surgery, the patient underwent pars plana vitrectomy. The next day, the IOP was 11 mm Hg, and the anterior chamber was deep. Four weeks later, vision was 20/40 in the right eye (due to cataract), the anterior chamber remained deep, and IOP was in the low teens.
All involved in cases of malignant glaucoma would like to prevent this situation. However, unless the fellow eye has had malignant glaucoma, the clinician cannot predict which patients will develop this problem.
References
- Byrnes GA, Leen MM, Wong TP, Benson WE. Vitrectomy for ciliary block (malignant) glaucoma. Ophthalmology. 1995;102(9):1308-1311.
- Fanous S, Brouillette G. Ciliary block glaucoma: malignant glaucoma in the absence of a history of surgery and of miotic therapy. Can J Ophthalmol. 1983;18(6):302-303.
- Ellis PP. Malignat glaucoma occuring 16 years after successful filtering surgery. Ann Ophthalmol. 1984;16:177-179.