Woman presents with high IOP and shallow anterior chamber

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An 81-year-old woman presented to New England Eye Center for a scheduled glaucoma follow-up. She reported blurry vision and pain in her right eye and ongoing chronic itching in both eyes. She denied headache, nausea or vomiting.

Her ocular history included primary open-angle glaucoma and allergic conjunctivitis. Her surgical history included cataract surgery in both eyes 1 year ago in Iran and laser peripheral iridotomies for narrow angles in both eyes years prior. She took timolol twice daily and latanoprost nightly in both eyes. She had allergies to apraclonidine and dorzolamide.

Christine Benador-Shen
Christine Benador-Shen
Malgorzata Dymerska Peterson
Malgorzata Dymerska Peterson

Her medical history was significant for hypertension, hyperlipidemia and anxiety. She was wheelchair-bound due to a previous stroke. She took losartan, metoprolol, simvastatin, Coumadin (warfarin), citalopram and alprazolam. On social history, she was a former smoker and spent her time in Tehran and Boston. Her family history was noncontributory.

Examination

On examination, the patient’s best corrected visual acuities were 20/200 in the right eye and 20/40 in the left eye. The vision had decreased in the right eye from best corrected 20/70 the prior visit. The right pupil was 5 mm, irregular and not reactive. The left pupil was also irregular with brisk reaction from 4 mm to 3 mm. IOP was 39 mm Hg in the right eye and 16 mm Hg in the left eye. Her highest IOP before this exam was 23 mm Hg in the right eye and 22 mm Hg in the left eye. IOP at her most recent visit was 16 mm Hg in both eyes.

Confrontation visual fields were full in both eyes. Extraocular movements were full. Slit lamp exam was notable for 1+ follicles and 2+ superficial punctate keratitis in both eyes. In the right eye, there was mild microcystic edema and a diffusely shallow anterior chamber with central anterior chamber depth equivalent to one to two corneal thicknesses. There was no lens-cornea touch. The left anterior chamber was deep and quiet. Peripheral iridotomies were patent in both eyes. Posterior chamber IOLs were within the capsular bag bilaterally with a dense posterior capsule opacification in the right eye.

No structures were visible on gonioscopy of the right eye, and the angle did not open with compression. Gonioscopy was open to scleral spur in the left eye. The optic nerves in both eyes had large cups with thin superior and inferior rims. The vitreous was clear, and the macula, vessels and periphery were within normal limits bilaterally. Her recent OCT retinal nerve fiber layer (RNFL) was within normal limits in the right eye and showed borderline thinning superiorly in the left eye (Figure 1). Humphrey visual field 24-2 had moderate reliability in both eyes and was overall full with rim artifact in both eyes.

moderate reliability
Figure 1. Humphrey visual field 24-2 of both eyes showed moderate reliability with rim artifact but was otherwise full. OCT of the RNFL was within normal limits in the right eye and showed borderline thinning superiorly in the left eye.

Source: Teresa Horan, MD, and Susan Liang, MD

What is your diagnosis?

See answer below.

High IOP

The differential diagnosis for a shallow anterior chamber includes pupillary block, suprachoroidal hemorrhage, choroidal effusion and malignant glaucoma.

Pupillary block was unlikely in this patient as she had a patent peripheral iridotomy and a diffusely shallow anterior chamber without iris bombe. In addition, pupillary block is less common in pseudophakic patients.

Suprachoroidal hemorrhage is usually characterized by acute severe pain and choroidal elevation. Recall that this patient had only mild eye pain and her dilated exam showed a normal flat retina without evidence of choroidal elevation. Because this patient was on Coumadin, we must also consider spontaneous suprachoroidal hemorrhages. Although these are rare, a dilated exam or B-scan is necessary to evaluate for suprachoroidal hemorrhage.

Choroidal effusion was also lower on the differential as the peripheral retina was normal. In addition, choroidal effusion is typically characterized by a shallow anterior chamber and low IOP, which was not seen in this patient.

The patient, with a history of primary open-angle glaucoma, bilateral cataract surgery and bilateral patent peripheral iridotomies for narrow angles, presenting with high IOP and diffusely shallow anterior chamber without structures visible on gonioscopy in one eye, likely had malignant glaucoma. Her decline in visual acuity was likely due to anterior displacement of the IOL and microcystic corneal edema.

Case continued

Given the IOP of 39 mm Hg in the right eye, a diffusely shallow anterior chamber and presumed diagnosis of malignant glaucoma, the patient was urgently treated with multiple IOP-lowering eye drops, oral Diamox (acetazolamide) and mydriatics (tropicamide and phenylephrine). She then underwent YAG capsulotomy and anterior hyaloidotomy through the patent iridotomy to disrupt the anterior hyaloid. Her post-procedure IOP was 26 mm Hg, and she was instructed to use timolol, latanoprost, brimonidine, cyclopentolate and atropine. The following day, her IOP was 18 mm Hg in the right eye, and the anterior chamber was deep with gonioscopy open to scleral spur in all quadrants. She was tapered off cyclopentolate after 3 months and was maintained on atropine, timolol, brimonidine and latanoprost. Her anterior chambers remained deep and IOP on target in both eyes. Her follow-up OCT RNFL and visual fields a few months later were stable without new defects noted.

Two years later, while visiting family in Iran, she was evaluated urgently for severe lid irritation and eye redness. She was diagnosed with hypersensitivity to atropine, and it was discontinued. She was seen in Boston 1 month later with resolution of her itching and periorbital erythema, but her IOP was elevated to 25 mm Hg. Gonioscopy showed no structures visible in the right eye. She was informed that her malignant glaucoma had returned, and surgical and medical options were discussed. The patient was unwilling to proceed with surgery and restarted atropine. One week later, her IOP improved to 12 mm Hg with normalized angle width. She was switched to preservative-free glaucoma drops and intermittently was treated with short courses of loteprednol for her itching.

Four months later, she presented urgently for worsening vision and mild right-sided brow pain. She had stopped the atropine again due to redness and itching. Her vision had deteriorated to finger counting at 1 foot, her IOP was 45 mm Hg, and her exam showed significant corneal microcystic edema and diffusely shallow anterior chamber, but no lens-cornea touch. She was treated with rounds of preservative-free dorzolamide-timolol and tafluprost and given atropine. Her IOP improved to 30 mm Hg with some resolution of pain. The following day, her IOP was still 30 mm Hg. Given her history of allergies to glaucoma eye drops and intolerance of many medications, including atropine, the patient agreed to undergo same-day pars plana vitrectomy. Her postoperative course was briefly complicated by hyphema as she was on anticoagulation. Since surgical treatment, her IOP has been well controlled on preservative-free dorzolamide-timolol and tafluprost without the need for atropine.

Discussion

Malignant glaucoma, also referred to as aqueous misdirection, occurs in 0.4% to 6% of patients who undergo surgery for angle closure glaucoma. It can also occur after laser procedures or spontaneously, although this is rarer. Typically, patients present with a red, painful eye and decreased vision. Onset can occur 1 day after surgery to several years later. A retrospective study of 1,689 patients found the mean time from glaucoma surgery to malignant glaucoma occurrence was 61 days. Risk factors for development of malignant glaucoma include hyperopia, history of angle closure, history of trauma or inflammation, and use of miotics. Examination shows diffuse shallowing of the anterior chamber. A patent iridotomy is required to make the diagnosis and differentiate it from pupillary block glaucoma. Ultrasound biomicroscopy and B-scan can be used to rule out choroidal effusion or suprachoroidal hemorrhage if the view is poor.

Generally, malignant glaucoma is thought to occur due to posterior pooling of aqueous fluid with compaction of the anterior hyaloid and decreased permeability of the vitreous. Pressure rises in the posterior chamber, leading to forward movement of the lens-iris diaphragm.

Many have postulated the exact mechanism behind malignant glaucoma. Most recently, Quigley and colleagues wrote that choroidal expansion is the precipitating event that causes elevated IOP and increased aqueous outflow. This increased outflow and a fixed amount of fluid leaving the vitreous result in anterior movement of the compressed vitreous humor and the lens-iris diaphragm. This cycle continues with further compression of the vitreous and shallowing of the anterior chamber.

Once malignant glaucoma has been diagnosed, it is important to start with medical management including cycloplegia, aqueous suppression, and escalation to YAG laser capsulotomy and anterior hyaloidotomy. Other medical treatment options include hyperosmotic agents and argon laser photocoagulation of ciliary processes. Studies have found 40% to 50% success with medical management alone. If medical management fails to control the IOP in 3 to 5 days, surgical intervention with vitrectomy is considered. The typical procedure is vitrectomy-iridectomy-zonulectomy to disrupt the anterior hyaloid face. This is successful in 65% to 90% of pseudophakic eyes and 25% to 50% of phakic eyes.

Another important consideration is prophylaxis for the fellow eye. If the fellow eye is closed or narrow on gonioscopy, one should consider a prophylactic peripheral iridotomy. It is also important to avoid miotics in these patients and consider aggressive cycloplegic therapy after surgery. As demonstrated in our patient, it is important to swiftly identify malignant glaucoma, especially later in the postoperative period, and to use a stepwise and multidisciplinary approach to treatment starting with medical management and escalation to surgery as needed.

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Elena Johaness

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