Angle-Closure Glaucoma and Plateau Iris Syndrome

The use of an over-the-counter cold remedy likely caused pupil dilation leading to acute angle closure.

By David M. Hicks, OD

A 64-year-old white man presented with a chief complaint of sudden vision loss in his left eye for 1 day. He was not using any ocular medications but reported using an over-the-counter (OTC) cold medicine 2 days earlier. There was no ocular pain at the time of presentation, although he noted a significant headache on the left side and eye pain the preceding day. His right eye was blind from glaucoma with no light perception vision. Visual acuity OS was 20/150+1, unable to be improved with pinhole. Pupils were sluggish, minimally reactive, and mid-dilated OU with a 4+ relative afferent pupillary defect OD and a superiorly peaked pupil OS. Extraocular motility was limited by the patient’s ability to follow the target but appeared full OU in all gazes.

INITIAL EXAMINATION

The anterior segment of the right eye was remarkable for a narrow anterior chamber, a small superior laser peripheral iridotomy (LPI), and an intraocular pressure (IOP) of 40 mm Hg. Slit lamp photographs OS showed diffuse conjunctival hyperemia and central corneal edema. Iris details were obscured, but a small LPI with questionable patency was also present superiorly OS. IOP was 15 mm Hg OS at 12:45 pm.

Gonioscopy showed a plateau iris configuration in all quadrants OD and a double-hump sign was present with compression. A similar appearance was noted OS, but views were limited due to corneal edema. No angle structures were visible OU. Corneal pachymetry was 524 μm OD and 924 μm OS. B-scan ultrasound OS revealed no intraocular masses and a fully attached retina. Cup-to-disc ratios were 0.9 × 0.9 or greater OD and approximately 0.4 × 0.4 OS.

The diagnosis of plateau iris syndrome with angle-closure glaucoma was made, and an argon laser peripheral iridoplasty (ALPI) was performed urgently on OS. After the iridoplasty, the patient was prescribed both topical 1% pilocarpine and prednisolone acetate ophthalmic suspension 1% (Pred Forte, Allergan, Inc.) OS q.i.d.

Figures 1 to 4 are anterior segment and gonioscopy photographs from the initial examination clearly demonstrating corneal edema OS and a closed angle OD. Clearing of the edema was seen during a follow-up examination 3 days later (Figure 5).

FOLLOW-UP EXAMINATION

After a few interval visits, the patient returned 8 weeks after his initial presentation for repeat ALPI with UCVA of 20/50-2 OS, which improved to 20/20 with a refraction of +1.25 D sphere at distance. Again, OD remained unchanged. The IOPs were 34 and 10 mm Hg at 1:15 pm, OD and OS, respectively. The repeat ALPI was performed OS without complication.

DISCUSSION

Angle-closure glaucoma is rare among white individuals with prevalence rates estimated to be from 0.09% to 2%.1,2 The condition can be acute or chronic, is typically unilateral, and is more common in hyperopic eyes and in older adults.3-6 A small corneal diameter and radius of curvature, shortened axial length, thick lens, anterior lens position, and shallow anterior chamber are risk factors.1,4,7 Women are roughly two to four times more affected across most populations.1,3 Increasing prevalence with age is due to thicker lenses, anterior lens displacement, and pupil miosis.3

Anatomy

There are three physiological mechanisms for primary angle-closure glaucoma (PACG) with relative pupillary block being the most common and accounting for about 90% of cases.2,4,7,8 Another cause for PACG is plateau iris, which is subdivided into plateau iris configuration and plateau iris syndrome. When the peripheral iris is moved anteriorly and affects the trabecular meshwork, it is called a plateau iris configuration.3 Plateau iris syndrome occurs when the IOP is elevated secondary to angle closure in an eye with plateau iris configuration and a patent peripheral iridotomy.3,6,7 In plateau iris syndrome, an LPI is an insufficient treatment because the peripheral iris remains apposed to the trabecular meshwork.

Signs and Symptoms

Classic findings in PACG, which were all exhibited by this patient, include dense corneal edema, ciliary flush, a sluggish and mid-dilated pupil, reduced vision, periocular pain, and headache.2,3,4,7 Typically, patients with PACG will also have markedly elevated IOP in the range of 35 to 70 mm Hg.3,4 This patient had an IOP of 15 mm Hg OS at presentation with a maximum of 19 mm Hg during follow-up, which is uncommon.

Dilation and Pharmacology

Prescription and OTC drugs are estimated to cause onethird of acute angle-closure glaucoma cases.9 Cold and flu relief products frequently contain a combination of doxylamine succinate and phenylephrine hydrochloride, both of which can cause dilation of the pupil. That is the suspected precipitating factor in this case, given the use of OTC cold remedy capsules followed by a very painful headache, light sensitivity, and sudden vision loss OS. Although it cannot be proven, severe IOP elevation likely occurred in that eye on the day of vision loss as well.

Treatment

Treatment of PACG varies; however, each case necessitates therapy directed at the underlying etiology. Topical and/or oral IOP-lowering medications are usually required in relative pupillary block and when a plateau iris causes acute angle closure.3,10,11 Unfortunately, approximately 50% of patients need more than medical therapy alone.12 To reduce iridotrabecular contact in plateau iris syndrome, the entire iris configuration must be changed. Use of ALPI is a popular choice for this indication,13-16 and it has also proven effective as a primary treatment for PACG or when medications fail.14-16 The use of ALPI in this patient on day 1 and a repeat treatment 2 months later caused iris contraction and deepening of the anterior chamber angle with subsequent IOP control and improvement in visual acuity.

CONCLUSION

Most patients who suffer an acute angle closure attack are unaware of their predisposing anatomical risk factors. In eyes with crowded anterior segments or plateau iris, pharmacological dilation from prescription or OTC drugs can induce angle-closure glaucoma. If an attack occurs, prompt diagnosis and management of the causative mechanism is important for a favorable long-term outcome. Medical therapy is usually required, but additional treatment with an ALPI may also be needed in patients with plateau iris syndrome.

David M. Hicks, OD, is an optometrist in San Jose, California. Dr. Hicks may be reached at davehicks.OD@gmail.com.

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