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Woman presents with elevated IOP
The patient had recently undergone bilateral laser peripheral iridotomies due to concern for narrow angles.
A 71-year-old woman was referred to the New England Eye Center for evaluation of elevated IOP in the left eye. Four weeks before presentation, she had undergone bilateral laser peripheral iridotomies due to concern for narrow angles. One week after the procedure, IOP in the left eye was elevated to 32 mm Hg, and an attempt was made to enlarge the peripheral iridotomy in the left eye at that time.
The patient’s ocular history was notable for cataract surgery in both eyes 6 years earlier followed by bilateral YAG capsulotomy. Her medical history included breast cancer, asthma, osteoarthritis, hyperlipidemia, gastroesophageal reflux disease and migraines. Her ophthalmic medications included brimonidine-timolol in the left eye twice daily. Her systemic medications included anastrozole, montelukast, beclomethasone dipropionate inhaler, atorvastatin and gabapentin. She had an allergy to penicillin. She did not smoke or use illicit drugs, and she drank alcohol only socially. Her family history was noncontributory. Her review of systems was unremarkable.
Examination
Source: Malgorzata Dymerska, MD, and Chandru Krishnan, MD
Upon initial examination at the New England Eye Center, the patient’s best corrected visual acuity was 20/25 in the right eye and 20/40 in the left eye. The pupils were symmetrically reactive without afferent pupillary defect. IOP measured 14 mm Hg in the right eye and 22 mm Hg in the left eye. Visual fields were full to confrontation bilaterally. Indirect gonioscopy revealed the anterior chamber angle was open to scleral spur with 1+ pigmentation in the right eye; in the left eye, the anterior chamber angle was open to posterior trabecular meshwork superiorly and inferiorly with 1+ pigmentation, and no angle structures were visualized temporally and nasally. Central corneal thickness was 606 µm in the right eye and 632 µm in the left eye.
On slit lamp examination, the anterior chamber was deep in the right eye and mildly shallow in the left eye. There was a non-patent peripheral iridotomy superiorly in the right eye and a patent peripheral iridotomy superiorly in the left eye. Posterior chamber IOLs were in place and well-centered in each eye.
Posterior segment examination showed pink optic nerves with sharp borders bilaterally, with a cup-to-disc ratio of 0.3 in the right eye and 0.1 in the left eye. No disc hemorrhages were noted.
OCT showed average retinal nerve fiber layer thickness of 117 µm in the right eye and 122 µm in the left eye with no segmental thinning. Humphrey visual field (24-2 SITA Fast protocol) was reliable and full in the right eye and showed nonspecific defects in the left eye (Figure 1).
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Elevated IOP
The differential diagnosis for angle closure in a pseudophakic patient includes plateau iris, aqueous misdirection, pupillary block, iridociliary cysts, ciliary body edema and tumors. Plateau iris is an inherent configuration of the anterior chamber angle that can result in angle closure. Aqueous misdirection typically presents with a notably shallow anterior chamber but could be considered in this case given the recent laser procedure. Lens-induced pupillary block is less likely in a pseudophakic patient with posterior chamber IOLs and no evidence of lens subluxation on exam. Furthermore, treatment with laser peripheral iridotomy typically relieves the block. Iridociliary cysts, ciliary body edema or tumors could be diagnosed with the help of ultrasound biomicroscopy (UBM).
Additional workup
UBM of the right eye showed an anteriorly directed ciliary process, absent ciliary sulcus, steep iris root and flat iris plane. The angle in the right eye did not appear occluded (Figure 2). UBM of the left eye had similar findings, but the angle appeared very narrow with iridotrabecular contact visualized in most areas (Figure 3). These findings are consistent with plateau iris configuration. UBM of the left eye also revealed material near the anterior lens capsule, which was suspected to be retained cortical material.
Discussion
Plateau iris configuration is caused by anteriorly positioned ciliary processes that push the iris forward. This specific organization of the anterior chamber can result in narrowing of the angle and cause acute or chronic primary angle closure, which is then called plateau iris syndrome.
Plateau iris is an important cause of primary angle closure to consider in young patients. It is seen more commonly in females than males. There may be a genetic component to the condition, as family history of plateau iris increases the risk for plateau iris configuration.
Plateau iris should be considered in patients with narrow angles or in those with angle closure who have relatively normal anterior chamber depth and a flat iris. Gonioscopic examination can reveal the characteristic “double hump” sign, in which the peripheral “hump” is caused by the ciliary process pushing the iris forward and the central “hump” is caused by the lens pushing the iris forward. UBM is helpful but not required for diagnosis.
Patients diagnosed with plateau iris should undergo laser peripheral iridotomy to alleviate any component of pupillary block. Argon laser peripheral iridoplasty may be helpful to thin and flatten the peripheral iris. Miotic drugs such as pilocarpine can also be used for long-term treatment. When appropriate, cataract extraction may be performed to open the angle. If these treatments are unsuccessful, trabeculectomy or glaucoma drainage device surgery can be considered.
Course continued
As there was no evidence of glaucoma at the time of our initial evaluation, medical management was chosen as the initial treatment strategy. The patient was started on topical pilocarpine three times daily in the left eye and was continued on brimonidine-timolol twice daily in the left eye. One month later, IOP in the left eye was unchanged at 22 mm Hg, and the anterior chamber angle in the left eye was still very narrow on gonioscopy. Pilocarpine was stopped, and the patient was started on topical dorzolamide and bimatoprost in the left eye. She was continued on brimonidine-timolol in the left eye. One month later, IOP in the left eye had improved to 12 mm Hg, and the anterior chamber angle appeared slightly more open. The patient continues to be followed closely for any signs of IOP elevation, peripheral anterior synechiae development or optic nerve damage.
- References:
- Basic and Clinical Science Course. Section 10: Glaucoma. American Academy of Ophthalmology. 2017;127-128.
- Mansoori T, et al. J Glaucoma. 2016;doi:10.1097/IJG.0000000000000263.
- Stefan C, et al. Rom J Ophthalmol. 2015;59(1):14-18.
- For more information:
- Malgorzata Dymerska, MD, and Chandru Krishnan, MD, can be reached at New England Eye Center, Tufts University School of Medicine. 800 Washington Street, Box 450, Boston, MA 02111; website: www.neec.com.
- Edited by Alison J. Lauter, MD, and Sarah E. Thornton, MD. They can be reached at the New England Eye Center, Tufts University School of Medicine, 800 Washington St., Box 450, Boston, MA 02111; website: www.neec.com.
Editor’s note: On Aug. 26, 2020, an incorrect photo in Figure 1 was replaced with the correct photo. The editors regret the error.