Woman’s IOP elevated despite patent laser peripheral iridotomy
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A 58-year-old white woman with primary angle closure suspect was referred to the New England Eye Center glaucoma service for elevated IOP after bilateral laser peripheral iridotomy.
The patient initially presented to an outside physician for routine ophthalmic examination and was found to have an elevated IOP of 34 mm Hg and 30 mm Hg in the right and left eyes, respectively, with no structures visible on gonioscopy. She was diagnosed as a primary angle closure suspect based on gonioscopy findings and subsequently underwent laser peripheral iridotomy (LPI) of both eyes with initial improvement in IOP. Upon follow-up, the patient was found to still have elevated IOP bilaterally, and medical therapy was started with twice-daily brimonidine and dorzolamide-timolol to both eyes. Despite topical therapy, the IOP remained elevated in the right eye, and patient was then referred to NEEC for further evaluation.
On presentation, the patient had no ophthalmic complaints. Notably, the patient denied any headaches, brow aches, eye pain or halos around lights. Medical history included insomnia for which she took zolpidem nightly. Ocular history was notable only for primary angle closure suspect with recent LPI bilaterally and concurrent use of brimonidine and dorzolamide-timolol twice daily. Surgical history was otherwise unremarkable.
Examination
Best corrected visual acuity was 20/20 in both eyes. IOP was 30 mm Hg and 14 mm Hg in the right and left eyes, respectively, by Goldmann applanation tonometry. Central corneal thickness was 558 µm in the right eye and 559 µm in the left eye. Pupils were 4 mm, round and reactive bilaterally without a relative afferent pupillary defect. Slit lamp exam was notable for shallow but formed anterior chambers, patent peripheral iridotomies and 1+ nuclear sclerosis cataracts bilaterally. Gonioscopy revealed closed angles in all quadrants bilaterally. Dilated fundus examination revealed a large cup-to-disc ratio of 0.75 in the right eye, with a thin superior rim and intact inferior rim. In the left eye, cup-to-disc ratio was 0.5 with intact superior and inferior nerve rims.
OCT demonstrated superior and temporal thinning of the retinal nerve fiber layer in the right eye (Figure 1). Standard automated perimetry by SITA testing demonstrated possible superior and inferior nasal step visual field deficits in the right eye (Figure 2).
Source: Allison Resnik, MD
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Elevated IOP, angle closure with patent LPI
The differential diagnosis for a patient who has elevated IOP with angle closure not responsive to LPI includes plateau iris syndrome, iridociliary cysts (pseudoplateau iris), peripheral anterior synechiae or lens-induced angle closure. As the patient’s gonioscopy exam did not demonstrate a “double hump” sign or peripheral anterior synechiae, both plateau iris syndrome and peripheral anterior synechiae were lower on our differential. Additionally, she had mild nuclear sclerotic cataracts, making lens-induced angle closure less likely. Therefore, our clinical suspicion was highest for a pseudoplateau iris configuration.
Workup and management
Ultrasound biomicroscopy (UBM) was obtained for further assessment and confirmed narrow iridotrabecular angles with multiple iridociliary cysts bilaterally (Figure 3). The diagnosis of pseudoplateau iris secondary to ciliary body cysts associated with angle closure glaucoma was made. Various treatment options were presented to the patient, including laser iridoplasty, clear lens extraction and additional medical treatment with topical IOP-lowering medication. The patient opted for nonsurgical management, and latanoprost was added to her topical medications. Since the addition of latanoprost, the patient has been stable upon follow-up with well-controlled IOP bilaterally, and she is followed in clinic every 6 months for ancillary glaucoma testing.
Discussion
Iridociliary cysts are epithelial-lined, fluid-filled structures that arise from the pigmented epithelial layer of the iris and ciliary body. Typically, these cysts do not result in any long-term sequelae and largely go unnoticed. However, when these cysts are found to involve more than 180° of the angle recess, they can push the iris root anteriorly and cause a pseudoplateau iris configuration, leading to angle closure, IOP elevation and possible glaucomatous damage. The diagnosis of iridociliary cysts is clinically challenging and typically requires adjunctive imaging such as UBM for better visualization.
Patients with iridociliary cysts present similarly to those with plateau iris syndrome, thus the term “pseudoplateau iris.” In plateau iris syndrome, there is anterior placement of the ciliary processes causing a repositioning of the peripheral iris leading to narrowing of the angle and subsequent obstruction of flow through the trabecular meshwork. In contrast, iridociliary cysts anatomically push the iris forward causing obstruction of flow through the trabecular meshwork.
Patients with iridociliary cysts are largely asymptomatic. However, it is important to ask patients if they have any symptoms such as an ipsilateral frontal headache, nausea, vomiting or halos around lights. It is also of utmost importance to ask what medications patients are taking, such as anticholinergic agents or adrenergic agents, which can contribute to intermittent angle closure attacks.
On slit lamp examination, there may be a shallow to normal anterior chamber depth with a flat iris. Gonioscopy demonstrates a narrow or closed angle. The definition of plateau iris syndrome is the presence of a persistent, occludable angle after a patent iridotomy. It is essential to obtain UBM because it allows for examination of structures posterior to the iris and aids in diagnosis and detection of anatomic changes in plateau iris configuration, iridociliary cysts or a ciliary body tumor. Differentiating between plateau and pseudoplateau iris is important for proper therapeutic management. Thus, UBM is a vital tool in the workup of these patients to allow for an accurate diagnosis.
Currently, there is no accepted consensus on the proper therapeutic strategy to control IOP and prevent further glaucomatous damage in patients with pseudoplateau iris secondary to iridociliary cysts. In most cases of iridociliary cysts, peripheral iridotomy is ineffective for IOP control and opening of the angle because pupillary block is not present. However, peripheral iridotomy should still be performed in any patient with appositional angle closure in case there is a component of pupillary block and to also aid in further classification of the etiology of angle closure.
Surgical intervention has been trialed for treatment of pseudoplateau iris and includes argon laser iridoplasty, in which an argon laser is used to burn areas of the peripheral iris and in turn cause contraction of the iris root and widening of the chamber angle. Additionally, many physicians are recommending phacoemulsification to aid in opening of the angle.
A systematic review assessed 14 eyes of seven cases with pseudoplateau iris configuration due to ciliary body/iridociliary cysts. In this review, all eyes underwent laser iridotomy with only two unilateral cases successfully developing subsequent open angle configuration. One case required laser iridoplasty, which initially removed the cysts and altered the configuration of the iris from convex to concave as confirmed on UBM. This controlled IOP for 6 months; however, the cysts reappeared with return of the pseudoplateau iris configuration and subsequent rise in IOP. In another case, an iridotomy and iridoplasty were performed with failure to control IOP, and ultimately clear lens extraction was required for control of IOP. Many of the eyes in this review did not respond to iridotomy and iridoplasty and ultimately required topical IOP-lowering medications for pressure control.
Our patient was diagnosed with iridociliary cysts based on UBM imaging. Her course has been well managed with topical IOP-lowering therapies with no further progression of her glaucoma. Different treatment options have been discussed if further glaucomatous progression develops in the future and includes laser iridoplasty, cataract surgery or glaucoma incisional surgery.
Even though iridociliary cysts are a rare cause of angle closure glaucoma, they should be on the differential for any patient who has persistently narrow angles with uncontrolled ocular hypertension or glaucoma despite patent iridotomies. Further research is needed to better understand the incidence and management of iridociliary cysts and their role in angle closure glaucoma.
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- For more information:
- Allison Resnik, MD, and Sarwat Salim, MD, can be reached at New England Eye Center, Tufts University School of Medicine, 800 Washington St., Box 450, Boston, MA 02111; website: www.neec.com.
- Edited by Allison V. Coombs, DO, MS, and Nisha S. Dhawlikar, MD, MPH. They can be reached at New England Eye Center, Tufts University School of Medicine, 800 Washington St., Box 450, Boston, MA 02111; website: www.neec.com.