Exudation, Response To Photocoagulation And Spontaneous Remission In A Case Of Bilateral Racemose Haemangioma

Abstract

Racemose haemangioma of the retina is a rare, presumably congenital vascular malformation characterized by dilated retinal arteries and veins that communicate directly without intervening capillaries. It may be either confined to the retina or combined with similar vascular malformations in the central nervous system on the ipsilateral side, in which case the condition is known as Wyburn-Mason or Bonnet–Chaume–Blanc syndrome (Wyburn-Mason 1943). The retinal racemose haemangioma may be a simple arteriovenous shunt or a complex array of intertwining vessels (Archer et al. 1973; Mansour et al. 1987; Shields et al. 2005) described as a ‘bag of worms’ (Mansour et al. 1987). The condition may involve the entire fundus or only a section of it. The more prominent the ocular involvement, the higher the likelihood of associated intracranial vascular malformations (Archer et al. 1973). A woman aged 57 years was referred for investigation for dry eyes as a routine part of a work-up for uncharacteristic arthritis-like complaints. As an incidental finding, a retinal arteriovenous shunt (racemose haemangiomata) was found in each eye, as well as an artery-to-artery anastomosis in the left eye (1, 2). Best corrected visual acuity (VA) was 1.0 in both eyes. Six months later, the patient presented again with visual loss of recent onset, exudative maculopathy and best corrected VA of 0.1 in the left eye (Fig. 1C). Fluorescein angiography demonstrated leakage from the transitional segment of an arteriovenous shunt and from its adjacent microvasculature (Fig. 1D). The condition responded favourably to two sessions of photocoagulation. Treatment of sufficient intensity to induce the appearance of vessel crimping was applied directly on the leaking shunt segment and over the adjacent area of leaking microvessels. The oedema resolved within weeks and the exudate over about 1 year. Best corrected VA improved gradually, to 0.3 after 3 months, 0.8 after 1 year and 1.0 after 4 years. Magnetic resonance imaging including angiography of the central nervous system was unremarkable. Colour fundus photographs (A, C, E) and fluorescein angiograms (B, D, F) of the left eye of a woman aged 57 years at presentation (A, D), when bilateral retinal arteriovenous shunts (racemose haemangiomata) were found during an investigation for dry eyes prompted by complaints of arthritis. Clinically insignificant leakage was seen from the shunt (B). Additionally, the branch retinal artery supplying the shunt was seen to be connected to an adjacent branch artery by an artery-to-artery anastomosis 1 disc diameter above the fovea. Best corrected VA was 1.0 in both eyes. Six months later, the patient presented again with visual loss of recent onset in the left eye. This reduction in best corrected VA to 0.1 was attributable to exudative maculopathy stemming from vascular leakage from the transitional segment of an arteriovenous shunt and its adjacent microvasculature (C, D). The condition responded favourably to two sessions of photocoagulation, after which best corrected VA improved to 1.0 (E, F). Treatment was applied directly to the leaking shunt segment and was of sufficient intensity to induce the appearance of vessel crimping, as well as in a near confluent grid pattern over the adjacent area of leaking microvasculature (E, F). Colour fundus photographs (A, C, E) and fluorescein angiograms (B, D, F) of the right eye in the same patient. At the age of 57 years (A, B), she was found to have an asymptomatic retinal arteriovenous shunt (racemose haemangiomata) in each eye. Six years later (B, E), the patient woke up with blurred vision in her right eye. She noted spontaneous improvement within 24 hours. When seen 4 days later, best corrected VA was 0.3 (C, D). Perivascular sheathing was seen around the transitional zone of the arteriovenous shunt and a macular star-like pattern of intraretinal exudate was seen in the fovea. Macular function as evaluated by multifocal ERG was generally suppressed and the patient complained of poor contrast vision. Both characteristics improved spontaneously, in concert with the disappearance of the exudate (E, F). Best corrected VA was 0.8 after 6 months. Six years after the initial visit, the patient presented with acute spontaneous blurring of the vision in the right eye that was followed within 1 day by spontaneous improvement. When we saw her 4 days later, the patient reported seeing a star-like pattern of radial lines around the blurred centre of the visual field in the right eye, which had best corrected VA of 0.3 and diffusely suppressed macular function on multifocal electroretinography (ERG). Fundus examination revealed a pattern of deep intraretinal or subretinal macular lines, in perfect correspondence with the figure seen by the patient (Fig. 2C) and matching the pattern of spokes previously seen in the left eye (Fig. 1C). At the tip of one of the loops of the arteriovenous communication in the right eye, a greyish tuft of angiographically non-perfused matter that appeared to be perivascular sheathing of an occluded vessel segment was observed (Fig. 2C), apparently emanating from the transitional zone of the arteriovenous shunt. Thus, no angiographic leakage was found, and, in agreement with this, optical coherence tomography showed the macula to be of normal thickness and profile. Macular function as evaluated by multifocal ERG was generally suppressed and the patient complained of poor contrast vision. Subjective visual function recovered gradually over the following 6 months, resulting in best corrected VA of 0.8 in the right eye. Macular function as assessed by multifocal ERG normalized and the radial pattern of neuroretinal lines disappeared entirely. We have been unable to find previous descriptions of artery-to-artery anastomoses, improvement after photocoagulation for exudative maculopathy, or a transient episode vascular exudation followed by spontaneous recovery in eyes with retinal racemose haemangioma. Our observations show that capillaries adjacent to the arteriovenous anastomosis or the anastomosing vessel segment itself may leak, intermittently or transiently. This suggests that because venous pressure is abnormally elevated in the shunt vessel, the adjoining retinal capillaries may be the primary site of leakage. The pressure gradient along the arteriovenous communication is unknown, but obviously it may lead to the venous transmural pressure being abnormally elevated, which will lead to reverse flow and excessive pressure in venous capillaries around the anastomosis. It is unknown what can prevent this from occurring. The present case suggests that the mechanisms of capillary defence can be decompensated, but it also shows that early recovery can take place, perhaps because spontaneous capillary occlusion occurs. If this fails to happen, photocoagulation seems to be an attractive therapeutic option.