SWS is a neurocutaneous disorder characterized by a PWS that affects the skin in the distribution of the ophthalmic branch of the trigeminal nerve.(3) The choroid is one of the most important vascular alteration sites associated with SWS.(13) Previous studies have shown increased choroidal thickness in SWS patients. However, the incidence of choroidal hemangiomas was not clear due to the limited number of subjects.(6, 7) Although a study and literature review conducted in 1976 found that 20%-70% of SWS patients suffered from choroidal hemangiomas,(5) the findings are limited by the case numbers and the efficiency of the examination because the incidence range exhibited large variation. Thus, choroidal changes in SWS patients should be re-evaluated. Clinically, ophthalmoscopy shows a bright red or red–orange appearance of the fundus related to the increase in well-formed choroidal vessels, while hemangiomas appear as diffuse or localized areas with a dark red color and a “tomato ketchup” appearance.(13) In the current study, we defined the choroid not only by the “ketchup” color of the fundus,(7) but also by an elevation of the retina/choroid complex with a low-to-medium reflective signal from the lesion on EDI-OCT. Thus, this could show direct visual evidence of choroid hemangiomas in SWS patients. However, EDI-OCT was not suitable for choroidal tumors that were > 1.0 mm in height and/or > 9.0 mm in diameter because the borders fell beyond the boundaries of detection.(14) In this study, in 21 eyes with choroidal hemangiomas and 7 eyes with a choroidal thickness > 1.0 mm of the outer border of the choroid could not be defined by EDI-OCT.
Because abnormal blood vessels in SWS and PWS patients are usually localized to a single region on one side of the body, a somatic mutation has been proposed to explain the etiology of SWS.(16) In 2013, Shirley and colleagues(3) found a GNAQ somatic mutation that affected 88% and 92% of tissue of SWS and PWS patients, respectively. In the current study, we found that both SWS secondary glaucoma and non-glaucoma PWS patients had an increased choroidal thickness. Nevertheless, the thickness of the choroid in SG patients was significantly greater than that in NGPWS patients, while a higher proportion of SG patients exhibited a vague choroidal-scleral junction due to excessive choroid thickness. Choroidal hemangiomas were only found in SWS secondary glaucoma eyes (55%). The results of our study might indicate that the GNAQ somatic mutation contributes to the choroid vessel dilation responsible for the thickening of the choroid. Moreover, the severity of the choroid thickness is correlated with SWS secondary glaucoma. However, what induces the varying degrees of choroid thickness in SG and NGPWS, whether choroid thickness play a role in the development of glaucoma or is just a secondary response, as well as the possible reason for onset of choroidal hemangioma in SWS patients remain unclear.
The etiology of SWS-induced glaucoma has been attributed to elevated episcleral venous pressures in juvenile- or adult-onset glaucoma,(17) whereas patients with early-onset glaucoma have anterior chamber angle anomalies.(18, 19) Thus, glaucoma can be difficult to control, even with combinations of various IOP-lowering medications. When medical management is unsuccessful, anti-glaucomatous surgical approaches have attempted to lower the IOP.(20) However, the surgical management of SWS-induced glaucoma is challenging for ophthalmologists, not only because of the low surgical success rate but also due to severe post-operative complications, such as choroidal effusion, choroidal detachment and exudative retinal detachment.(21–24) Post-operative complications of the posterior segment mostly occurred after filtering surgeries, possibly due to relieving the eye pressure too quickly.(20) In this study, 19 eyes underwent anti-glaucoma surgery. Among them, 13 underwent filtering surgery, including trabeculectomy (1 eye), Ex-PRESS implantation (11 eyes) and valve implantation (1 eye). Six eyes exhibited posterior segment ocular complications, including 4 with retinal and choroidal detachment and 2 with mild retinal detachment. All of these complications occurred in eyes with choroidal hemangioma. Most notably, 2 eyes (1 patient) were found to have mild retinal detachment by EDI-OCT after trabeculotomy. As a non-filtering surgery mostly applied to infant patients, trabeculotomy is believed to be safe and effective for children. Ikeda and colleagues(25) found that 3.4% of eyes exhibited retinal detachment during developmental glaucoma after trabeculotomy due to an enlarged globe. However, previous studies did not find posterior segment complications in SWS patients.(26, 27) In our study, the axial lengths in the two eyes were 24.2 mm and 23.1 mm. The globe was previously enlarged in a 4-year-old child.(28) However, it was worth noting that this patient had two eyes with choroidal hemangiomas. According to the pattern of the retinal detachment and the lack of a retinal hole, we were inclined to believe that the posterior segment complication was due to exudative retinal detachment. A previous study also showed exudative retinal detachment after a strabismus surgery in an SWS patient.(29) This indicates that only a moderate change of IOP or manipulation of the eyeball could disturb choroidal hemangiomas and increase the effusion. It is worth noting that post-operative choroidal detachment and exudative retinal detachment in SWS-induced glaucoma patients were typically self-limiting, with all 6 eyes recovering within 3 months of topical glucocorticoid and atropine administration.