Glaucoma in Sturge-Weber Syndrome

Glaucoma in Sturge-Weber Syndrome GERHARD W. CIBIS, MD,* RAMESH C. TRIPATHI, MD, PhD, t BRENDA J. TRIPATHI, PhDt

Abstract: Trabeculectomy specimens from three eyes with Sturge-Weber syndrome were examined histopathologically. Changes in the trabecular meshwork-Schlemm's canal system were similar to findings in old age and in primary open-angle glaucoma. Two mechanisms for glaucoma are theorized. In cases with buphthalmos and congenital glaucoma, the chamber angle is often anomalous, as in other types of congenital glaucoma. In later onset juvenile cases, the chamber angle more often appears normal. A premature aging of the trabecular meshwork Schlemm's canal complex, as shown by us histopathologically, is a primary cause of juvenile glaucoma. It is suggested that both mechanisms relate to the abnormal hemodynamics of episclera and chamber angle, due to persistence of Streeter's primordial vascular plexus. [Key words: congenital, facial hemangiona, glaucoma, gonioscopy, histopathology, nevus flammeus, Sturge-Weber, trabeculectomy, trabeculotomy.] Ophthalmology 91:1061-1071, 1984

The etiology of glaucoma in cases with facial nevus flammeus has been enigmatic since the first description of this relationship by Schirmer. 1 The association of intracranial angiomata with nevus flammeus, and glaucoma was made by Sturge, 2 later by Webe~ as well as others4-7 which established the classic triad of what is now commonly called Sturge-Weber syndrome. Variants of the syndrome are listed by Francois5 and Geeraets6

and include Jahnke's syndrome (nevus flammeus) without glaucoma, Schirmer's syndrome with buphthalmos, Lawford's syndrome of late onset glaucoma without buphthalmos, Mille's syndrome with choroidal hemangioma but without glaucoma. Klippel-Trenaunay8 is nevus flammeus of the face and extremities, possibly on different sides of the body, with hypertrophy of underlying soft tissue and bone with or without the SturgeWeber triad. We consider all of these syndromes as subclassifications of Sturge-Weber syndrome.

From the Children's Mercy Hospital, Kansas City, Missouri, and the Department of Ophthalmology, University of Kansas,* and the Department of Ophthalmology, University of Chicago.t

Presented at the Eighty-eighth Annual Meeting of the American Academy of Ophthalmology, Chicago, Illinois, October 30-November 3, 1983.

Supported in part by the Childrens Mercy Eye research fund, and National Institutes of Health grant #EY03747.

Reprint requests to Gerhard W. Cibis, MD, 4620 JC Nichols Parkway #421, Kansas City, MO 64112.

A number of pathogenetic mechanisms appear to have been proven as causes of glaucoma in SturgeWeber syndrome. These include anterior chamber malformations similar to those seen with other types of congenital glaucoma.4·9-

13 Occlusion of the chamber angle with anterior synechiae4·12·13 is seen more commonly as a secondary phenomenon in adults with choroidal hemangioma and retinal detachment.4·10

•12·13

Phelps14 demonstrated elevated episcleral venous pressure and postulated that this in turn elevated intraocular pressure.

The relationship to the area of distribution of the nevus flammeus to that of the trigeminal nerve has been stressed. 10

•15 Based on this presumed relationship, neu

ronal influences have been cited as possible causes of hypersecretion of aqueous by the ciliary body.4·10·12·13

The exact respect for the midline by the trigeminal nerve, however, is a hallmark of its distribution pattern which the nevus flammeus notoriously fails to respect. The nevus flammeus generally crosses over or falls short of the midline, and often extends into the territory of the upper cervical nerves (Fig 1 ). This speaks against a relationship to the trigeminal nerve.

Numerous examples of anomalous chamber angles resembling those seen with congenital glaucoma exist.4·10·12·13·16 Convincing drawings of anomalous SturgeWeber chamber angles are found in Duke-ElderY Weiss, 10 reported flat iris insertion in some parts of the

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OPHTHALMOLOGY • SEPTEMBER 1984 • VOLUME 91 • NUMBER 9

chamber angle with other areas appearing normal. Prominent vascular loops at the iris root, and the frequent presence of blood in Schlemm's canal are among gonioscopic findings in Sturge-Weber syndrome that are reminiscent of congenital glaucoma.4

•9

-13

Histopathologic confirmation of a chamber angle similar to that found in congenital glaucoma has also been reported. Iris insertion anteriorly onto the trabecular meshwork, ciliary muscle insertion directly into the trabecular meshwork rather than onto the scleral spur, and the presence of a "Barkan's membrane" are oftdescribed examples of congenital glaucoma with the same type of chamber angle malformations found in Sturge-Weber syndrome (10, 12, 13).

Thirty percent of affected patients are thought to develop glaucoma. 4 Of these, 60% develop glaucoma early enough in life (prior to age two) to develop buphthalmos, while the remaining 40% do not develop glaucoma until late childhood or young adulthood.4

•10

The chamber angle has a more normal appearance in the late onset glaucoma cases. 10

•16

We report our experience with nine cases of SturgeWeber and one case of nevus flammeus without glaucoma. One of the Sturge-Weber patients was bilateral. Glaucoma is defined as a pressure elevation greater than 23 mmHg and with a pressure difference greater than 6 mmHg in the eye with the nevus flammeus as compared to the other eye. Buphthalmos and increased optic nerve cupping of the involved eye were often present but not needed for the diagnosis of glaucoma. Trabeculectomy specimens were taken from three eyes. On electron microscopy, the trabecular meshwork showed changes similar to those seen in old age and in primary openangle glaucoma.

MATERIALS AND METHODS

We report our results of nine cases with Sturge-Weber syndrome requiring glaucoma surgery and one case of nevus flammeus without glaucoma. Five of the ten patients presented with buphthalmos and cloudy corneas in the eye ipsilateral to the nevus flammeus in the first six months of life. Two patients had Klippel-Trenaunay syndrome. All five bupthalmos patients had trabeculotomy (as per Harms17

) as the primary surgical procedure. Only one patient has failed to remain controlled up to this time. Follow-up ranged from two to five years.

The one trabeculotomy failure has gone on to another trabeculotomy, a goniotomy, and finally a trabeculectomy with filtering bleb formation (case A). Gonioscopy of the chamber angle (Fig 2) in this eye showed iris processes and an anterior insertion of the iris base. Multiple blood channels in the region of Schlemm's canal were also visible. The surgery included the standard trabeculectomy (as per Cairns)18 with extensive wet field cautery of the episcleral venous plexus. There was no unusual bleeding, iris or ciliary process prolapse, or

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prolonged shallowing of the anterior chamber. Pressure has remained successfully controlled with topical medication for the past year. The patient is now six years of age. Of the other primary trabeculotomy cases two are on continuing anti-glaucoma medication as well.

Four of the remaining five cases all had a delayed onset of their glaucoma past 2 to 3 years of age. Three cases had goniotomies as the primary procedure performed by other surgeons. Two of these failed and were successfully treated with secondary trabeculotomy; in one case surgery was carried out twice. This patient had a prolonged postoperative period of flat anterior chamber and hemorrhage but has done well subsequently with topical anti-glaucoma medication. Follow-up time since the last surgery is now two years. The patient had congenital iris processes adherent to the trabecular meshwork and cornea (Fig 3).

Trabeculectomy was the primary procedure in both eyes of the only bilateral case of nevus flammeus and glaucoma in our series (case B). This patient was ten years old at the time of trabeculectomy. There was a history of seizures. Ophthalmological examination at age three showed normal fixation patterns and corneal diameters. The patient was lost to follow-up until the time of surgery. Examination at that time revealed visual acuity of 20/40 in the right and 20/200 in the left eye. Applanation tonometry revealed intraocular pressure of 34 mmHg in the right eye and 40 mmHg in the left eye. External examination revealed episcleral hemangiomata bilaterally and an increased corneal diameter of the left eye. The cup/disc ratio was 0.9 on the right and 0.6 on the left. Gonioscopy of both eyes showed normal, fully open chamber angles. The patient underwent a left trabeculectomy in March 1978, followed by a right trabeculectomy in June of 1978. Diathermy was used to cauterize episcleral vessels. An approximately 4 mm X 4 mm partial thickness scleral flap, two mm anterior and posterior to the corneoscleral junction, was raised. A block of deeper limbal tissue (specimen B) was excised (Fig 4a-d color). There were no surgical complications. Postoperative pressures have remained around I 0 mmHg and the amount of disc cupping has diminished bilaterally.

The final case presented with apparent buphthalmos of the right eye on the side of the nevus flammeus at age six months. However, at the time of evaluation under anesthesia corneal diameters diameters were equal, I 0.5 mm in each eye. Intraocular pressures were normal. Gonioscopy revealed anomalous angle vessels in the right eye ipsilateral to the nevus flammeus. These vessels were not present in the left eye. There was an episcleral hemangioma more prominent inferiorly. No choroidal hemangioma was seen on fluorescein angiography. Fluorescein angiography of the iris and conjunctiva revealed abnormal prominence and interconnection of iris vessels (Fig 5a-c). Telangiectactic vessels or hemangiomata on the iris have been described before.7 A direct communication between iris and episcleral vasculature could not be shown.

CIBIS, et al • STURGE-WEBER SYNDROME

Fig 1. Top left, nevus flammeus in a patient with Sturge-Weber syndrome that was successfully treated with trabeculotomy (2-year follow-up). The nevus does not strictly adhere to the distribution of the trigeminal nerve, falling short of or crossing the midline in various places. Fig 2. Top right, Case A. Anomalous chamber angle, right eye. Iris processes adhere to trabeculum, like other types of congenital glaucoma. Fig 3. Second row left, inferior chamber angle showing iris processes adherent to the meshwork and cornea. This patient needed two goniotomies, followed by two trabeculotomies, for pressure control. Fig 4. Bottom, trabeculectomy procedure; a, raising the limbal flap. Prominent episcleral vascular plexus is visible; b, vessels are cauterized; c, scleral flap is raised and block of deeper limbal tissue excised; d, anterior scleral flap is reposed and sutured, conjunctival flap closed.

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RESULTS

HISTOPATHOLOGIC AND ELECTRON MICROSCOPIC EXAMINATION

The excised trabeculectomy specimens from case A (right eye), and from case B (both eyes), were fixed in

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Fig 5. a, iris fluorescein angiogram in a six month old SturgeWeber patient without glaucoma. Early arterial phase. Episcleral hemangioma and prominent conjunctival vessels are visible inferiorly. b, early venous phase showing an abnormal amount of iris vasculature. c, late venous phase showing no leakage from the anomalous iris vessels. The persistent pupillary membrane vessel appears to be blood-bearing.

buffered glutaraldehyde and processed for light and electron microscopy. Meridional sections showed that both specimens from case B consisted of deeper tissue of anterior sclera and peripheral cornea together with the scleral spur, Schlemm's canal, trabecular meshwork and Schwalbe's line. The specimen from case A did not include the line of Schwalbe. Histopathologic and ultrastructural findings were similar in all three specimens.

Fig 6. Light photomicrograph of trabeculectomy specimen in meridional section showing compact trabecular meshwork (TM) and pericanalicular region (P) of Schlemm's canal (SC) (toluidine blue, epoxy-resin section, original magnification X800).


There was no evidence of a hyalinized membrane or endothelial membrane covering the inner aspect of the trabecular meshwork.

Apart from slight disorganization in the arrangement of the inner uveal beams, the overall architecture of the trabecular meshwork and Schlemm's canal was well preserved (Fig 6). The trabecular meshwork was generally compact; the intertrabecular spaces of the deeper uveal and corneoscleral regions of the meshwork contained amorphous material and, in some regions, the meshwork appeared partly hyalinized (Fig 7). · The individual trabecular beams, especially those of the uveal meshwork, were thickened for the age of the patients. 19

-22 The

cortical zone was especially prominent and was associated with long-spacing collagen. Elastic tissue which showed degenerative changes was also associated with the longspacing collagen. The endothelial covering of many beams showed degenerative changes (Fig 8).

The pericanalicular region on the trabecular aspect of Schlemm's canal was generally compact and showed both hyper- and hypocellularity, degenerative changes in the cellular and fibrous components and an abnormal accumulation of fine fibrillar material, with a beaded pattern, which is normally associated with basal lamina material in this region (Fig 4). Other extracellular components included granulo-amorphous material, basal lamina material, long-spacing collagen, and banded and non-banded plaques of granulo-amorphous material. The endothelial lining of Schlemm's canal was intact but attenuated and there was a paucity of the vacuolar structures normally encountered in the endothelial lining of the canal. The subendothelial basement membrane was generally prominent (Fig 9). Degenerative changes, although to a lesser degree, were also seen in the pericanalicular region of the comeoscleral wall.

DISCUSSION

The notoriously poor response of Sturge-Weber glaucoma patients to goniotomy, an otherwise successful procedure in congenital glaucoma cases, led to the reevaluation of classic clinical and histopathologic reports as to the underlying pathogenic mechanism of the glaucoma. Taking into account that not all cases had anomalous chamber angles, Weiss10 postulated that two mechanisms, namely increased pulse and venous pressures as well as the known chamber angle anomalies, were at fault. In Weiss' clinical experience, the chamber angles appeared normal in cases where glaucoma developed late compared to infantile cases where the chamber angle was nearly always anomalous. He theorized that congenital or infantile cases had both a chamber angle and a hemodynamic component, but that in juvenile and early adult onset cases the hemodynamic component predominated.

Phelps14 measured episcleral venous pressure and found it to be elevated in all glaucomatous SturgeWeber eyes to a mean of 18.1 mmHg compared to 9.0

for normals and 9.1 for eyes with nevus flammeus without glaucoma. He therefore endorsed Weiss's thought that a hemodynamic component was part of the pathogenesis ofSturger-Weber glaucoma and that the elevated episcleral venous pressure represents that hemodynamic component. The success of trabeculectomies in four of his cases was cited in support of this contention.

Rosenbaum23 had similar surgical success with trabeculectomies in four cases of whom he stated that "gonioscopy showed no specific abnormalities." Light and electron microscopy of the trabeculectomy specimens showed no evidence of an anterior chamber membrane but abnormal episcleral vessels were present in every case. He therefore concluded that pathologic examination in his cases supported the hypothesis that elevated episcleral venous pressure was responsible for glaucoma in Sturge-Weber syndrome.

Of the five surgeries on Rosenbaum's four patients, three had surgical complications. Ciliary processes prolapsed into the trabeculectomy wound in two cases, along with lens zonules and vitreous in the third case. Expulsive hemorrhage, choroidal effusion, prolonged persistence of flat anterior chambers and excessive anterior chamber hemorrhage are well documented complications in open eye surgery in Sturge-Weber cases and are thought to relate to the episcleral vessel network.

Aware of the risk of expulsive hemorrhage with open surgical procedures in these cases24 and of the failure of goniotomies, we have done trabeculotomies as the primary procedure for Sturge-Weber glaucoma in five of six cases at the time of presentation. There has been one failure and a second case required a repeat trabeculectomy. A primary trabeculotomy was successfully performed on both eyes of the only binocular case in our series and as a final procedure in the failed trabeculotomy case.

Our experience with successful trabeculotomy as a suitable surgical procedure for the management of the raised intraocular pressure in many patients with SturgeWeber syndrome is shared by others. Induction of a low intraocular pressure preoperatively and careful cauterization of the dilated subconjunctival and episcleral vessels would seem to be prerequisites for avoiding complications of hemorrhage, expulsion or prolapse of intraocular contents, all of which are well known complications ofSturge-Weber glaucoma surgery. Our success with trabeculotomy as a primary procedure, an essentially closed eye approach, supports the concept that the pathogenesis of the early onset buphthalmos cases where this procedure was done are similar to other forms of congenital glaucoma in which trabeculotomy has proven to be a highly successful operation. 17

The changes in the trabecular meshwork-Schlemm's canal of patients we examined were abnormal for their young ages. To a great extent these changes are similar to those seen in old age and in primary open-angle glaucoma. 19

-21 We feel these histologic changes found

in three trabeculectomy specimens from Sturge-Weber glaucoma cases are primary. The premature ageing may

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Fig 7. Electron micrograph of trabecular meshwork and Schlemm's canal (SC) Note the compactness of the meshwork in this section and of the pericanalicular region (P) (original magnification X5600).

be accelerated by anatomic conditions, raised intraocular pressure and medical treatment.

Case B (both eyes) had not undergone previous surgery or laser treatment. In this patient the alterations would

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seem to represent a primary premature or accelerated aging defect or a process similar to that seen with primary open-angle glaucoma.22 Alternatively, one can speculate that structural changes in the trabecular mesh-


Fig 8. Electron micrograph of uveal trabeculae showing degenerative changes in the endothelial covering (E) and thickened cortical zone (CZ) with accumulation of basement membrane material and long-spacing collagen. The elastic tissue (EL) is also associated with the long-spacing collagen (original magnification X39,000).

work system were brought about by the mechanical stress associated with raised intraocular pressure, altered hemodynamics from the episcleral vascular plexus, pos-

sibly compounded by the anti-glaucoma drugs used. In case A the previous glaucoma surgery may have played a role.

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Fig 9. Electron micrograph of pericanalicular region of Schlemm's canal (SC) on the trabecular aspect. The extracellular space is largely occupied by fine fibrillar material (F) associated with the basal lamina material. The basement membrane (BM) of the endothelial lining is conspicuous. The cellular component shows degenerative changes while some cells have a dilated rough-surface endoplasmic reticulum (ER) and contain flocculent material (original magnification X40,000).

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The excessive iris vascularization shown by fluorescein angiography in our one case without pressure elevation (Fig Sa-c) leads to speculation as to what role such an increased blood flow might play in development of secondary angle anomalies. Anomalous angle vessels were seen in most of our glaucomatous cases and are well described in the literature.4

•5

•9

•10

-13 Direct vascular

connections between the episcleral hemangioma and the prolific iris vessels could not be proven. Weiss, 10 however, felt that such a direct communication exists.

Phelps14 argued that the elevated episcleral venous pressure as shown by him in Sturge-Weber cases would be reflected as an elevation in intraocular pressure. In our case, without glaucoma intraocular pressure was 12 mmHg in each eye. This is less than the 18.1 ± 6.4 mmHg episcleral venous pressure he measured in glaucomatous eyes, but in line with the 9.1 ± 1.6 mmHg episcleral venous pressure he measured in Sturge-Weber patients without glaucoma. What hemodynamic differences there are between the two groups is unknown. Nontheless it seems difficult to us to explain glaucoma pressures of 32.0 ± 12.2 mmHg, in Phelp's series, purely on the much lower episcleral venous pressures. The calculation of Nesterov25 that an 135-fold lessening of outflow facility of the collector channels would be needed to produce an 10 mmHg increase in intraocular pressure is further evidence against a direct primary role of elevated episcleral venous pressure in Sturge-Weber glaucoma.

The surgical success of trabeculotomy, goniotomy, and trabeculectomy in controlling intraocular pressure also speaks against the theory of raised episcleral venous pressure as the main cause of Sturge-Weber glaucoma. The success of these procedures favors a primary block in the trabecular meshwork and Schlemm's canal system. This is supported by the light and electron microscopic findings in our trabeculectomy specimens.

We believe that glaucoma in Sturge-Weber syndrome results from two main factors. In early onset cases, the angle has developed anomalously. In late onset cases, the block is most likely in the trabecular meshwork Schlemm's canal system. The premature aging of the trabeculae as shown in our cases together with known chamber angle anomalies of both the congenital and secondary synechiae type, may be related to hemodynamic variations in the iris and chamber angle vasculature. The theory that vascular disturbances in SturgeWeber syndrome appear early in embryogenesis, (11.5 mm stage) as an anomaly in or persistence of Streeter's primordial plexus, from which the ocular circulation is derived, 26

•27 would explain the abnormal evolution of

congenital chamber angle anomalies, as well as the later onset glaucomas with more normal appearing chamber angles.

REFERENCES

1. Schirmer R. Ein Fall von Teleangiektasie. Albrecht von Graefes Arch Ophthalmol 1860; 7:119-21.

2. Sturge WA. A case of partial epilepsy, apparently due to a lesion of one of the vaso-motor centres of the brain. Trans Clin Soc Lond 1897; 12:162-7, (also Abstract in Br Med J 1879; 1 :704).

3. Weber FP. Right-sided hemi-hypotrophy resulting from right-sided congenital spastic hemiplegia with a morbid condition of the left side of the brain, revealed by radiograms. J Neurol Psychopathol 1922; 3:134-9.

4. Font RL, Ferry AP. The phakomatoses. lnt Ophthalmol Clin 1972; 12(1 ): 1-50.

5. Fran9ois J. Ocular aspects of the phakomatoses. In: Vinken PJ, Bruyn GW, eds. Handbook of Clinical Neurology. Vol. 14: The Phakomatoses. New York: Elsevier, 1972; 639-44.

6. Geeraets WJ. Ocular Syndromes, 3rd ed. Philadelphia: Lea and Febiger, 1976; 410.

7. Waardenburg PJ. Genetics and Ophthalmology. Assen: Van Gorcum, 1963; 1365-86.

8. Kramer W. Klippei-Trenaunay syndrome. In: Vinken PJ, Bruyn GW, eds. Handbook of Clinical Neurology. Vol. 14: The Phakomatoses. New York: Elsevier, 1972; 390-404.

9. Barkan 0. Goniotomy for glaucoma associated with nevus flammeus. Am J Ophthalmol 1957; 43:545-9.

10. Weiss Dl. Dual origin of glaucoma in encephalotrigeminal haemangiomatosis. Trans Ophthalmol Soc UK 1973; 93:477-93.

11. O'Brien CS, Porter WC. Glaucoma and naevus flammeus. Arch Ophthalmol 1933; 9:715-28.

12. Shaffer RN, Weiss Dl. Congenital and Pediatric Glaucoma. St. Louis: CV. Mosby, 1970.

13. Duke-Elder S, ed. System of Ophthalmology. Vol. 11: Diseases of the Lens and Vitreous; Glaucoma and Hypotony. London: Kimpton, 1969; 637-40.

14. Phelps CD. The pathogenesis of glaucoma in Sturge-Weber syndrome. Ophthalmology 1978; 85:276-86.

15. Cushing H. Cases of spontaneous intracranial hemorrage associated with trigeminal nevi. JAMA 1906; 47:178-83.

16. Asano Y, Kimura R. Glaucoma associated with Sturge-Weber syndrome: a case report. Glaucoma 1983; 5:186-9.

17. Harms H, Dannheim R. Trabeculotomy-results and problems. Bibl Ophthalmol, 1970; 81:121-31 (Adv Ophthalmol Vol. 22).

18. Cairns JE. Trabeculectomy; preliminary report of a new method. Am J Ophthalmol 1968; 66:673-9.

19. Tripathi RC. Aqueous outflow pathway in normal and glaucomatous eyes. Br J Ophthalmol 1972; 56:157-74.

20. Tripathi R. Strukturelle Hinweise auf den Abflusswiderstand bei Glaucoma chronicum simplex. In: Leydhecker W, ed. GlaukomSymposion WGrzburg, 1974. Stuttgart: Enke 1976; 13-38.

21. Tripathi RC, Tripathi BJ. Functional anatomy of the anterior chamber angle. In: Duane TD, Jaeger EA. eds. Biomedical Foundations of Ophthalmology. Philadelphia: Harper & Row, 1982; vol. 1, chap. 10.

22. Tripathi RC, Tripathi BJ. Trabecular changes in bilateral SturgeWeber syndrome. Proc lnt Soc Eye Res 1982; 93.

23. Rosenbaum LJ. Glaucoma in Sturge-Weber syndrome. Birth Defects 1982; 18(6):645-9.

24. Bellows AR, Chylack L T Jr, Epstein DL, Hutchinson BT. Choroidal effusion during glaucoma surgery in patients with prominent episcleral vessels. Arch Ophthalmol 1979; 97:493-7.

25. Nesterov AP. Role of the blockade of Schlemm's canal in pathogenesis of primary open-angle glaucoma. Am J Ophthalmol 1970; 70:691-6.

26. Alexander GL. Sturge-Weber syndrome. In: Vinken PJ, Bruyn GW, eds. Handbook of Clinical Neurology. Vol. 14: The Phakomatoses. New York: Elsevier, 1972; 223-40.

27. Duke-ElderS, ed. System of Ophthalmology. Vol. 3, part 2: Normal and Abnormal Development; Congenital Deformities. London: Kimpton, 1963; 1120-7.

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Discussion by

Merlyn Rodrigues, MD

The authors have reported interesting clinical and surgical results of nine cases of Sturge-Weber syndrome, treated by trabeculotomy and trabeculectomies. Trabeculotomy was sue-

cessfully performed as the primary procedure in five of six patients including a case that required bilateral surgery. The trabeculectomy specimens from the latter showed structural

Fig 1. Trabeculectomy specimen from a five-year-old child with glaucoma (without buphthalmos) and Sturge-Weber syndrome. Upper inset shows an extension of Descemet's membrane (arrows) across the inner uveal meshwork (toluidine blue, X330). Lower inset shows scroll-like excresences of Descemet's membrane (arrows) lining the inner uveal meshwork (X 1170). Electron micrograph shows trabecular beams (T) and occasional patches of long spacing collagen (arrow). Scant elastin-like areas are indicated (X) (X21,000).

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changes that were unusual for a 10-year-old individual and are more typical of alterations associated with premature aging and with primary open-angle glaucoma. 1

-3 To illustrate this

point, a five-year-old patient of Dr. George Spaeth had typical Sturge-Weber syndrome with nevus flammeus of the left side of the face, prominent episcleral veins, left choroidal hemangioma, cupped optic disc, corneal clouding of the left eye and left meningeal hemangioma. There was no evidence of buphthalmos. Histological examination of the trabeculectomy specimen disclosed abnormal peripheral Descemet's membrane extending across the anterior portion of the inner uveal meshwork (Fig 1, inset). Electron microscopy disclosed abnormal excrescences of Descemet's membrane lining a portion of the inner uveal meshwork (Fig 1 ). The trabecular beams appeared of normal thickness and the juxtacanalicular meshwork and Schlemm's canal were unremarkable.

It is uncertain, however, whether the structural changes described by Cibis et al could account for the elevated intraocular pressure in Sturge-Weber syndrome, since the possible effect of antiglaucoma medications should also be considered, as mentioned by the authors. Other mechanisms that have been suggested in the pathogenesis of glaucoma in SturgeWeber syndrome include elevated episcleral pressure,4 choroidal hemangioma,5

•6 and anomalies of the anterior chamber angle.

The hypothesis proposed by Cibis and associates that a two-

fold mechanism could account for glaucoma in Sturge-Weber patients is intriguing. However, it is difficult to assess the significance of histologic changes based on specimens from two patients. Electron microscopic studies of additional trabeculectomy specimens could be useful in our understanding of mechanisms of glaucoma in this entity and the authors should be encouraged to pursue their work further.

References

1 . Rohen JW. Why is intraocular pressure elevated in chronic simple glaucoma? Anatomical considerations. Ophthalmology 1983; 90:758-65.

2. Tripathi RC. Pathologic anatomy of the outflow pathway of aqueous humour in chronic simple glaucoma. Exp Eye Res 1977; 25(Suppl):403-7.

3. Rodrigues MM, Spaeth GL, Sivalingam E, Weinreb S. Histopathology of 150 trabeculectomy specimens in glaucoma. Trans Ophthalmol Soc UK 1976; 96:245-55.

4. Phelps CD. The pathogenesis of glaucoma in Sturge-Weber syndrome. Ophthalmology 1978; 85:276-86.

5. Font RL, Ferry AP. The phakomatoses. lnt Ophthalmol Clin 1972; 12(1 ): 1-50.

6. Weiss Dl. Dual origin of glaucoma in encephalotrigeminal heamangiomatosis. Trans Ophthalmol Soc UK 1973; 93:477-93.

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Glaucoma in Sturge-Weber Syndrome