Glaucomas: Sturge Weber Syndrome

Core Messages

››Glaucoma in Sturge-Weber Syndrome (SWS) differs from other types of glaucoma in terms of presentation and management.

››Angle abnormalities and elevated episcleral venous pressure are responsible for glaucoma seen in SWS patients.

››The success of various treatments may depend on the age at which glaucoma develops (early childhood vs. late childhood or adulthood).

››Ocular surgery in SWS patients is associated with a greater risk of choroidal effusion or expulsive hemorrhage. There are techniques to reduce these risks.

46.1  How Does Glaucoma in SturgeWeber Syndrome (SWS) Differ Clinically from Other Glaucomas?

Not only is SWS associated with intracranial and facial angiomas (nevus flammeus, see Fig. 46.1), it can also be associated with several anomalous ocular features. Most frequently, hemangiomas of the lid, episclera or conjunctiva (see Fig. 46.2), iris or ciliary body are present. Less common features include hyperchromia, iris neovascularization, tortuous retinal vessels (see Fig. 46.3), scleral melanosis, strabismus,

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Fig. 46.1  Nevus flammeus on the left side of the face. Photo courtesy of Jonathan Dutton

and homonomyous hemianopsia because of cerebral hemangiomas. Anderson’s rule says that when a hemangioma involves the upper lid, there is ipsilateral intraocular involvement. Sturge-Weber syndrome is a disorder of neural crest cells, also known as encephalotrigeminal angiomatosis. The facial cutaneous angioma is usually unilateral, present at birth, and distributed over the first and second divisions of the

Fig. 46.2  Hemangioma of the conjunctiva. Photo courtesy of Jonathan Dutton

Fig. 46.3  Tortuous retinal vessels. Photo courtesy of Jonathan Dutton

trigeminal nerve. However, it can be bilateral in 10–30% of the cases. Meningeal hemangiomas are associated with progressive calcification of arteries and cerebral cortex resulting in mental defects in 60%, seizures in 85% and reduced life expectancy [14]. SWS has no race or sex predilection and no hereditary pattern has been established. The onset of glaucoma in SWS ranges from early childhood to adulthood.

Choroidal hemangiomas are present in 30–55% of individuals with SWS [2], and of all choroidal hemangiomas 50% are associated with SWS. These lesions tend to be flat, diffusely involve the posterior pole, and are termed “tomato catsup” fundus. These hemangiomas significantly increase the risk of intraoperative complications.

Glaucoma occurs in 30–70% of individuals with SWS [11,16], and it seems that patients with upper eyelid involvement are more likely to develop glaucoma [8]. When the facial angioma is unilateral, glaucoma­ is nearly always unilateral and ipsilateral. When individuals with SWS have glaucoma, the onset is before 2 years of age in 60% while the remaining 40% develop glaucoma later in childhood or in adulthood.

There are two main theories to explain the development of glaucoma in SWS – anterior chamber angle anomalies and elevated episcleral venous pressure. These anomalies have been studied histologically. The angle in SWS may be similar to that seen in primary infantile glaucoma [2] with a poorly developed scleral spur, thickened uveal meshwork, anteriorly inserted iris root onto the base of the trabecular meshwork, iris stroma covering trabecular meshwork, prominent iris processes, abnormalities of Schlemm’s canal, persistent embryonic mesodermal tissue, and abnormal juxtacanalicular connective tissue. These abnormalities are thought to cause congenital or early-onset glaucoma in SWS. Those with early-onset glaucoma have the typical features of congenital glaucoma including buphthalmos, anisometropia, amblyopia, and advanced optic nerve cupping. In individuals with later-onset glaucoma, the angle may be minimally affected or appear normal. In juvenile-onset SWS glaucoma [6] investigators have reported premature aging of the angle tissues, including aging changes of the trabecular meshwork–Schlemm’s canal complex with compact trabecular meshwork, amorphous material in the intertrabecular spaces, hyalinized trabecular meshwork, thickened trabecular beams, and degenerative changes in the elastic tissue.

Elevated episcleral venous pressure is also present in SWS [2, 11]. In separate studies, Weiss and Phelps found elevated episcleral venous pressure from arteriovenous fistulas in SWS patients. Phelps hypothesized that the extent of episcleral hemangiomas correlates with the severity of glaucoma. Aside from angle abnormalities and elevated episcleral venous pressure, glaucoma can also develop in the setting of retinal detachment with forward displacement of the iris and secondary angle-closure from peripheral anterior synechiae or neovascularization [6, 8].

Summary for the Clinician

››SWS is characterized by intracranial and facial angiomas, hemangiomas of the lid, episclera, conjunctiva, iris, ciliary body, or choroid.

››Glaucoma occurs in 30–70% of individuals with SWS and patients with upper eyelid involvement are more likely to develop glaucoma. Of those that develop glaucoma, 60% develop it before 2 years of age, while the remaining 40% develop it later in childhood or adulthood.

››Glaucoma may develop in SWS because of anterior chamber angle anomalies or elevated episcleral venous pressure.

››Glaucoma can also develop in the setting of retinal detachment with forward displacement of the iris and secondary angle-closure from peripheral anterior synechiae or neovascularization.

46.2  Is Management of Glaucoma in

SWS Different from the Typical

Management of Primary Open

Angle Glaucoma (POAG)?

Since SWS is relatively uncommon, there are no large, long-term studies regarding the optimal management of glaucoma in this population. However there are several smaller studies and case reports that provide insight regarding the treatment of these individuals.

46.2.1  Medical Treatment of Glaucoma

in SWS

The main difference in managing glaucoma in SWS compared to POAG is that the glaucoma is less responsive to medical therapy [16]. Of the topical therapies available, aqueous suppressants and miotics tend to be the most successful. A few studies regarding the use of latanoprost in these patients have shown that there is a higher nonresponse rate, especially in patients with early-onset glaucoma. However there are reports where patients with late-onset glaucoma had a robust response to latanoprost [4, 18].

46.2.2  Surgical Treatment of Glaucoma

in SWS (Angle Surgery and

Trabeculectomy)

When the onset of glaucoma is early, angle abnormalities are thought to be the source of elevated intraocular pressure (IOP). Since medical therapy is usually unsuccessful, goniotomy or trabeculotomy is typically the first line of therapy because these procedures target the anatomical abnormality. However these surgical approaches are typically less effective in SWS glaucoma than in primary congenital glaucoma [12]. When ineffective, the patient may require filtering surgery to control IOP. In general, standard trabeculectomy without antimetabolites has limited success in children, probably because of the rapid healing response and thick Tenon’s layer.

Iwach et al. reviewed their medical and surgical management of glaucoma in 36 eyes of 30 patients with SWS [10]. They evaluated efficacy of interventions based on the length of time to subsequent medical or surgical intervention. In other words, a long time interval to subsequent intervention means better efficacy. Median stable intervals (length of time without increase in IOP or change in optic nerve) were 12 months with goniotomy, 21 months with trabeculotomy, 34 months with trabeculectomy, 25 months with argon laser trabeculoplasty, and 57 months with medications. They recommend goniotomy or trabeculotomy over trabeculectomy which was complicated by choroidal effusions in 24% of patients. A posterior sclerotomy prior to entering the eye in filtration surgery has been recommended by some investigators to minimize the risk of serous choroidals and hypotony, while others recommend tight suturing of the flap instead [2]. However, since there are no large, prospective, randomized trials examining the use of posterior sclerotomies, their need remains debatable.

In juvenile or later-onset glaucoma, topical medications are typically the first-line of therapy but they frequently fail. Argon laser trabeculoplasty has been used to treat glaucoma in SWS but appears to have limited success [10]. The next line of therapy in these individuals is trabeculectomy. Ali et al. reported results in 7 eyes of 6 patients with SWS treated with trabeculectomy without antimetabolite who were followed for at least 9 months. Postoperatively, two eyes had adequate IOP control without the use of medications, four eyes required additional medication, and one eye required three additional trabeculectomies and postoperative medications to achieve control [3].

Antimetabolite-augmented trabeculectomy has been used in pediatric patients and a few case reports have shown them to be successful in refractory congenital glaucoma [13]. However, in patients with SWS less success has been reported [17]. The long term effects of antimetabolite use in children must be considered given their longevity and potentially poor hygiene that can increase the risk of blebitis.

Alternatively, two centers in India have reported success in SWS patients using primary combined tra- beculotomy-trabeculectomy for early-onset glaucoma without the placement of prophylactic sclerotomies [1, 12]. One study of 10 eyes of 9 patients showed IOP reductions from 28 to 11.8 mmHg, and all eyes maintained a postoperative IOP less than 16 mmHg without medications over a mean follow-up of 28 months [12]. Another study of 18 eyes reported IOP £ 22 mmHg in 11 eyes after mean follow-up of 42 months with or without medications [1]. One benefit of these combined glaucoma procedures is that the surgery targets both mechanisms of SWS glaucoma, namely the angle abnormality (via trabeculotomy) and elevated episcleral venous pressure (via trabeculectomy).It also appears to be safe. Mandal used intravenous mannitol 1 h before surgery to lower IOP intraoperatively to minimize a sudden surgical drop in pressure and choroidal effusions [12].

46.2.3  Glaucoma Drainage Devices

in SWS Glaucoma

In late-onset glaucoma, the etiology of elevated IOP is elevated episcleral venous pressure, and treatment for this population is aimed at bypassing this venous system via trabeculectomy or an aqueous shunting procedure when medical therapy fails. Glaucoma drainage devices have been shown to be helpful in the management of glaucoma in SWS. In a study of 11 eyes of 10 patients with SWS glaucoma that underwent Ahmed valve placement, the cumulative probability of success was 79% at 24 months, 59% at 42 months, and 30% at 60 months, comparable to results of tube shunts in other types of glaucoma [9]. Success was defined as IOP less than 21 mmHg, without additional glaucoma surgery, expulsive choroidal hemorrhage, or retinal detachment. Treatment failed in four eyes with implant extrusion in one eye and IOP greater than 21 mmHg in three eyes at the last follow-up.

Budenz et al. used a two-staged implantation of the Baerveldt glaucoma implant (BGI) in patients with

glaucoma in SWS. This technique was used in an attempt to reduce the potential complications of choroidal effusion and hemorrhage and to improve longterm IOP control. Allowing encapsulation around the plate before inserting the tube is thought to minimize hypotony when the tube becomes functional. However, they also used posterior sclerotomies at the time of surgery, prior to entering the eye. They report that all ten eyes of nine children had adequate IOP control (£21 mmHg) and none needed additional glaucoma surgery during a 3 year follow-up. There were a few minor complications including two eyes with transient serous choroidal effusions, but they did not result in permanent visual loss. No intraoperative or postoperative suprachoroidal hemorrhages occurred. The authors conclude that two-stage BGI surgery appears to be a safe and effective treatment for refractory glaucoma in children with SWS [5].

46.2.4  Cyclodestruction in SWS

Glaucoma

As it is in the treatment of many cases of glaucomas, one of the last procedures in management of glaucoma in SWS for patients who have failed other medical and surgical interventions is ablation of the ciliary body. In one study, cryocoagulation of the ciliary body resulted in a mean postoperative IOP of <22 mmHg in 6 of 7 patients after a mean follow-up of 4–5 years [16] (see Fig. 46.4). The risks of this procedureincluding phthisis - limit its use in the early management of glaucoma or when visual acuity is good.

Fig. 46.4  Cyclophotocoagulation for refractory glaucoma in a patient with SWS. Photo courtesy of JoAnn A. Giaconi