Sir,

The differential diagnosis of the causes of angle-closure glaucoma may be difficult in eyes with complicated anterior segments. Accurate diagnosis, followed by prompt and effective treatment, is essential to successful management.

We report a case of progressive anterior chamber (AC) shallowing after combined phacoemulsification with posterior chamber intraocular lens (PCIOL) and tube-shunt implantation. Based upon the ultrasound biomicroscopy findings, creation of a patent laser iridotomy deepened the AC and allowed incisional surgery to be avoided.

Case report

A 65-year-old woman with Axenfeld–Rieger syndrome and two failed trabeculectomies was referred for evaluation of progressive anterior chamber (AC) shallowing after combined phacoemulsification (posterior chamber intraocular lens (PCIOL)), and tube-shunt implantation. Her best-corrected visual acuity was 6/9 and intraocular pressure was 11 mm Hg OU. Slit-lamp biomicroscopy revealed scarred conjunctiva, band keratopathy, shallow AC, unobstructed tube tip, vitreous prolapse, and two surgical iridectomies that transilluminated. B-scan examination of the posterior pole was unremarkable. A translucent membrane with anterior bowing was present on the PCIOL surface (Figure 1a).

Figure 1
figure 1

Anterior segment photographs of the left eye: (a) at presentation showing marked AC shallowing, extensive iris/cornea contact (oblique arrows) and bowed fibrin membrane over the PCIOL (horizontal arrow); (b) after argon laser iridotomy (horizontal arrow), showing a deep chamber and flattened iris and fibrin membrane contours.

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Ultrasound biomicroscopy (P40 UBM, Paradigm Medical Industries, Salt Lake City, UT, USA), performed with the patient supine using an immersion technique and a 50-MHz transducer, revealed a shallow AC, a thin membrane with an anterior convexity over the PCIOL, iridectomy obstructed by vitreous and a convex iris contour (Figures 2a, b and 3a), suggestive of pupillary block secondary to an occluded pupil and imperforate surgical iridectomies.

Figure 2
figure 2

Ultrasound biomicroscopy images: (a) surgical iridectomy blocked by prolapsed vitreous (oblique arrow); (b) closed temporal iridocorneal angle (arrowheads), convex iris contour continuous with the fibrin membrane (vertical arrow) above the PCIOL (horizontal arrow), ciliary body (CB), and ciliary sulcus (asterisk).

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Figure 3
figure 3

UBM images: (a) shallow AC with bowed fibrin membrane (arrows) above the PCIOL (asterisk), and convex iris before iridotomy; (b) deep AC, flattened membrane above the PCIOL (asterisk), and flat iris after iridotomy.

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Argon laser iridotomy performed near the tip of the tube, which was the area of greatest distance between the iris and cornea (Figure 1b) resulted in immediate deepening of the AC, flattening of the iris contour, and flattening of the anteriorly bowed membrane over the PCIOL (Figures 1b and 3c).

Comment

Distinguishing aqueous misdirection from pupillary block at the slit-lamp may be impossible in some cases.1, 2 Malignant glaucoma was suggested by AC shallowing, the presence of two iridectomies and the marked forward displacement of the PCIOL.2 The UBM findings of prolapsed vitreous obstructing the iridectomy (Figure 2a), wide ciliary sulcus, and convex iris contour (Figure 2b) were the clues to rule out the diagnosis of aqueous misdirection,3 and confirmed the diagnosis of pupillary block angle-closure. Laser iridotomy allowed movement of aqueous into the AC and restoration of normal anterior segment architecture without the need for further incisional surgery in this already scarred eye.