Editor, O sler Rendu Weber disease is an autosomal-dominant hereditary haemorrhagic telangiectasia (HHT) leading to arteriovenous malformations in the skin, mucosa and viscera (Osler 1901). While mucosal complications may cause epistaxis and gastrointestinal bleeding, additional visceral involvement frequently concerns the lung, liver or brain. The diagnosis of HHT is based on three of four criteria: epistaxis, telangiectasia, visceral lesions and appropriate family history. Frequent ocular abnormalities include conjunctival telangiectasia causing bloody tears. Retinal malformation include visceral angiodysplasia such as arteriovenous fistula, angiectasia, phlebectasia and angioma (Vase & Vase 1979; Brant et al. 1989; Mahmoud et al. 2002). We performed photodynamic therapy (PDT) to treat choroidal neovascularization (CNV) that occurred secondary to parafoveal telangiectasia in a patient with HHT. A 76-year-old woman complained of decreased visual acuity (VA) of 20/60 with metamorphopsia in the left eye. Hereditary haemorrhagic telangiectasia had been diagnosed 10 years earlier due to telangiectasia located at her tongue, distal fingers and conjunctiva (Fig. 1A, B). Although epistaxis occurred frequently, no surgery was required. On fundus examination in both eyes, the retinal vessels appeared well perfused (Fig. 1C, D). However, the macula in the left eye showed a significant oedema with subretinal lipid exudates superiorly and temporally (Fig. 1D). Fluorescein angiography disclosed parafoveal telangiectasia in both eyes (Fig. 1E, F), whereas an additional occult CNV caused a severe leakage temporal to the macula in the left eye (Fig. 1F). Optical coherence tomography in the left eye showed a neuroretinal elevation of 480 mm. Our patient had no additional retinal disease including venous occlusion, hypertensive or diabetic retinopathy. After the patient had signed informed consent, one PDT session was performed. One year after PDT the metamorphopsia disappeared and the subject’s VA stabilized at 20/125. Some subtle exudates and retinal pigment epithelium (RPE) defects maintained temporal to the macula (Fig. 2A). Fluorescein angiography showed a mild atrophy of the choriocapillaris in the area of the PDT application; however, there was no persisting leakage or oedema (Fig. 2B). Optical coherence tomography disclosed no subretinal fluid and a retinal thickness of 240 mm. The tumour growth factor-beta (TGF-b) binding protein endoglin was recently identified as causing HHT with pulmonary arteriovenous malformations. While a corresponding candidate gene for endoglin is localized at 9q33–34 (McAllister et al. 1994), additional genetic studies have demonstrated the pivotal role of TGF-b signalling during angiogenesis. Knockout mice for endoglin, endothelial-specific deletion of the TGF-b-type 2 receptor (TbR2) or activin receptor-like-kinase-5 (ALK-5) failed to differentiate vascular smooth muscle cells as well as endothelial cells, inducing fragile and dilated blood vessels (Carvalho et al. 2004). The prevalence of ocular abnormalities in HHT is approximately 35% for extraocular lesions (conjunctival telangiectasia) and only 10% for retinal vascular malformations (Brant et al. 1989). Although this retrospective analysis observed intraocular findings, the authors questioned the coherence of HHT in selected cases. A great variety of retinal malformations may occur, including telangiectatic vessels at the optic disc or papillomacular bundle, and beading of retinal vessels. Retinal parafoveal telangiectasia, as presented in our HHT patient, has not yet been described in detail. Our HHT patient clearly presented typical findings of parafoveal telangiectasia in both eyes. Whether the idiopathic parafoveal telangiectasia was part of the underlying disease or just coincidental remains speculative as overall retinal involvement in HHT is very rare. However, the presence of telangiectasia in other mucosa and viscera structures supports this assumption. The unilateral symptomatic alteration was associated with severe leakage and oedema corresponding from an adjacent occult CNV in the left eye. Photodynamic therapy reduced the leakage and exudation significantly, maintaining stable VA for our patient. Novel treatment modalities such as intravitreal triamcinolone or antivascular endothelial-growth-factors (anti-VEGF) are currently under investigation in proliferative disease. Further research is necessary to determine the influence of endoglin in the pathogenesis of parafoveal telangiectasia in order to evaluate a possible treatment approach by anti-TGF-b in vascular disease such as HHT.
Search from 250 M+ research papersSearch from 250 M+ research papers
Jul 25, 2016
+ 4
Open Access