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Editor,—The pseudoexfoliation syndrome is characterised by the presence of light grey or white flakes on the pupillary margin and anterior lens capsule, the surfaces of the iris, zonules, ciliary body, hyaloid, trabecular meshwork, and the endothelial surface of the cornea. This syndrome is generally thought to be accompanied by open angle glaucoma. However, in some reports, the anterior chamber angle is narrow,1-3 and in other cases shown to be angle closure glaucoma.45 The relation between the pseudoexfoliation syndrome and angle closure glaucoma is unclear. We used the ultrasound biomicroscope to determine the pathogenesis of angle closure glaucoma in a patient with the pseudoexfoliation syndrome.
CASE REPORT
An 80-year-old Japanese woman complained of blurred vision and pain in the left eye. Angle closure glaucoma of the left eye was diagnosed by an ophthalmologist. Pilocarpine eye drops were prescribed, and the patient was referred to our department. On initial examination, her corrected visual acuity was right eye 70/100 and left eye 20/100, and the intraocular pressures were right eye 13 mm Hg and left eye 37 mm Hg. Slit-lamp examination revealed a shallow anterior chamber in the right eye and a markedly shallow anterior chamber in the left eye. Pseudoexfoliative substance was observed on the pupillary margin of the both eyes; moderately dense cataract was present in both eyes. Gonioscopy revealed a narrow (grade 2) angle in the right and an even narrower angle (grade 1) in the left eye. A densely pigmented trabecular band was present in both eyes. Glaucomatous disc cupping was observed in both fundi by ophthalmoscopy performed without mydriasis.
An ultrasound biomicroscope (50 MHz Ultrasound BioMicroscope, Humphrey Instruments, Inc, San Leandro, CA, USA) was used to evaluate the mechanism of the angle closure glaucoma. Ultrasound biomicroscopy demonstrated a narrow angle at the mid peripheral anterior chamber in all sections of the right eye, and a slit-like, narrow or closed angle in the left eye (Figs 1, 2). Thick, well defined zonules were observed in all sections of both eyes, some of which were loose (Fig 1). Both lenses were spherically shaped, and anterior poles moved forward. The iris showed a marked anterior bowing that was consistent with pupillary block. The thickness of the right lens was 5.4 mm, as measured by A-scan echography. The thickness of the left lens could not be measured.
Ultrasound biomicroscopic image of the anterior segment of the inferior section in the right eye. Zonule is loose and the lens has a spherical shape. The iris shows a marked anterior bowing with the presence of pupillary block. The angle is narrow at the mid peripheral anterior chamber.
Ultrasound biomicroscopic image of the anterior segment of the inferior section in the left eye. Zonules are thick and well defined, and the lens has a spherical shape. The angle is closed with pupillary block.
The administration of the pilocarpine drops was halted, and laser iridectomy was performed in both eyes. The anterior chambers of both eyes were of normal depth; the intraocular pressure fell to a normal level in the left eye after the procedure. Ultrasound biomicroscopic examination showed a normal, wide open angle, except for the inferior and superior segments of the left eye which showed persistent peripheral anterior synechiae. The iris showed a straight configuration. On the following day, when ultrasound biomicroscopy was performed after the instillation of pilocarpine, numerous loosened zonules were seen in all sections of both eyes. Lens thickness as measured by A-scan echography was 5.9 mm in the left eye.
COMMENT
Ultrasound biomicroscopy revealed thick, well defined zonules that appeared to be coated with pseudoexfoliative materials. The resulting loosened zonules presumably caused the spherical shape of the lens and increased the axial thickness. The anterior pole of the lens appeared to have moved forward and increased the intraocular pressure by creating pupillary block.
In cases with a shallow anterior chamber or angle closure glaucoma accompanied by the pseudoexfoliation syndrome such as that presented here, an immediate laser iridectomy is indicated without the use of pilocarpine drops. The instillation of pilocarpine drops exacerbates pupillary block so that its use is contraindicated. When cataract surgery is performed in such cases, careful attention should be paid to zonular dialysis.