Ultrasound biomicroscopic evaluation in Sturge Weber syndrome without glaucoma.

Abstract

Sir, A 9-year-old girl was referred to us by a paediatrician for an ophthalmological check-up. She was known to have Sturge Weber syndrome and had consulted the paediatrician for treatment of the port wine stain on her face. On examination, apart from the angiomas present bilaterally along the distribution of the ophthalmic and maxillary division of the trigeminal nerve, we did not find any other lesions on the body. There was no history of seizures or any other neurological deficit. Her intellectual development was normal. The family history was non-contributory. The patient did not have any visual complaints and her visual acuity was 20/20 with − 1 diopter sphere in both eyes. Slit-lamp examination revealed an extensive episcleral vascular plexus in the nasal part in the left eye and a similar plexus of vessels temporally and inferiorly in the right eye. Conjunctival vascular malformations were also evident in the same areas and at the limbus, extending from 5 o'clock to 10 o'clock nasally in the left eye and from 6 o'clock to 10 o'clock in the right eye (Fig. 1). There were patches of episcleral pigmentation superiorly in both eyes. However, there were no associated pigmented patches on the skin of the face, nor on the nasal or buccal mucosa. The subject's intraocular pressure (IOP) measured after diurnal variation was 12 mmHg in both eyes. Gonioscopy of both eyes showed an open angle with a densely pigmented trabecular meshwork (Fig. 2) and a vascular arcade of anomalous vessels seen anteriorly in the sclera. Both eyes had a 0.5 : 1 cup : disc ratio with a healthy neuroretinal rim. There was no evidence of any retinal vascular tortuosity, nor was there any difference in the colour of the fundus of each eye on indirect ophthalmoscopy. Fluorescein angiography of the anterior segment revealed a filling up of the extremely tortuous limbal and episcleral vascular plexus. Fundus angiography ruled out choroidal haemangiomas. Limbal vascular malformations inferiorly in the right eye. Goniophotograph of the inferior angle. The thin arrow shows the vascular plexus in the sclera. The arrowhead shows dense pigmentation of the angle. On ultrasound biomicroscopy, we observed a layer of prominent episcleral vessels and a localized area of intrascleral vascular malformation near the irido-corneal angle in both eyes (Fig. 3). Ultrasound biomicroscopic visualization of the intrascleral vascular haematoma (two thin arrows) and episcleral plexus of vessels (thick curved arrow). Humphrey 30–2 automated field analysis was within normal limits and a computer tomography (CT) scan of the head was also normal. The patient was advised regular follow-up. Increased episcleral venous pressure is an important cause of glaucoma in Sturge Weber syndrome and vascular haematomas indicate the presence of increased venous pressure. The other hypothesis regarding the pathogenesis of glaucoma in Sturge Weber syndrome concerns the presence of angle anomalies such as a poorly developed scleral spur, thickened uveal meshwork, anterior insertion of the iris root in the trabecular meshwork (Weiss 1973) and incomplete development of Schlemm's canal (Dunphy 1935). Clusters of abnormal vessels in the trabecular meshwork have also been reported on histological examination (Mwinula et al. 1994). The dense pigmentation seen on gonioscopy in this patient is possibly a milder expression of an angle cleavage anomaly. Weiss (1973) found vascular haematomas of the anterior episclera and conjunctiva in each of his series of Sturge Weber patients and we believe in his hypothesis that a combination of increased episcleral venous pressure and a congenital angle malformation contribute in variable proportions to the development of raised IOP. Vascular malformations of the conjunctiva and episclera are frequently found in Sturge Weber patients without glaucoma; however, the vessels become very prominent in eyes that have developed glaucoma. Although the patient described did not have glaucoma, this could be because the episcleral venous pressure was not raised to the point at which it might cause glaucoma. This was evident from the fact that the vascular malformations were localized and not prominent. Ultrasound biomicroscopic evidence of vascular malformations, especially near the angle, should also be looked for, as should the presence of episcleral vascular malformations. The presence of dilated superficial and intrascleral vessels on ultrasound biomicroscopy in a case of Sturge Weber syndrome was first described by Kranemann et al. (1998). However, their patient had full-blown glaucoma and had already been treated by cyclocryotherapy and surgery. Moreover, the vessels shown by Kranemann et al. (1998) were not at the limbus. In cases of Sturge Weber syndrome, early detection by gonioscopy and ultrasound biomicroscopy of vascular malformations at the limbus, and serial follow-up for enlargement, may alert the ophthalmologist to the possibility of the development of increasing episcleral venous pressure.