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Brief Reports

Double Prepapillary Arterial Loops Associated with Superior Branch Macular Artery Occlusion

Vedantham, Vasumathy MS, DNB, FRCS; Ramasamy, Kim DNB; Namperumalsamy, P MS; Cunningham, Emmett T MD, PHD, MPH

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Indian Journal of Ophthalmology: Apr–Jun 2005 - Volume 53 - Issue 2 - p 126-128
doi: 10.4103/0301-4738.16178
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Abstract

Liebreich, in 1871, first described the prepapillary arterial loop, a congenital vascular anomaly that originates from a main branch of the central retinal artery on the optic disc. The clinical and fluorescein angiographic features of these vascular anomalies are well-described in the literature.123456 Though usually asymptomatic, such vascular anomalies can cause branch retinal artery occlusion. To the best of our knowledge, this is the first case report of a superior branch macular artery occlusion in an eye with two independent prepapillary arterial loops, following a Valsalva-like mechanism. The possible aetiopathogenesis of the occlusion is discussed.

Case Report

A 16-year-old girl was referred to the Retina-Vitreous service of our institute with a complaint of transient blurred vision in her left eye 2 months earlier, following a bout of severe sneezing. The blurred vision was noted by the patient immediately following a bout of sneezing but she could not qualify it further. The patient said that immediate ophthalmic consultation had not been sought since the episode of blurred vision was transient and cleared spontaneously. Past ocular and medical histories were otherwise unremarkable.

On ocular examination, the visual acuity was 6/6 bilaterally. Anterior segment examination of both the eyes was normal. Posterior segment examination of the right eye was essentially unremarkable. Posterior segment examination of the left eye revealed two independent preretinal arterial loops over the superior part of the optic disc that continued as superonasal and superotemporal branches of the central retinal artery [Figure 1a]. The superotemporal loop was more convoluted than its nasal counterpart. Glial tissue was observed overlying these loops. Both loops showed pulsations synchronous with the carotid pulse upon oculodigital massage, consistent with their arterial origin. The superior branch macular artery could barely be visualised in its proximal part and appeared as a subtle white ghost vessel devoid of blood, consistent with a previous occlusive episode. A few superficial retinal haemorrhages were noted in the territory of the occluded vessel. No intravascular emboli or plaques were detected. In addition, a collateral to the occluded superior branch macular artery was observed arising from the inferior branch macular artery.

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Figure 1a:
Left fundus showing two independent preretinal arterial loops with overlying glial tissue, continuing as the superotemporal and superonasal branch retinal arteries. An occluded superior branch macular artery (arrow head) is evident. Superficial retinal haemorrhages are seen in the territory of the occluded vessel. A collateral arising from the inferior branch macular artery to the occluded vessel is also seen

Fluorescein angiography showed a normal background choroidal fluorescence. There was brisk filling of the inferior papillary branch of the central retinal artery along with its inferotemporal, inferonasal, and inferior macular branches. The origin of the occluded superior branch macular artery could not be established. Separate origins of the two arterial loops were evident [Figure 1b]. Three seconds elapsed before the prepapillary loops became as intensely fluorescent as the inferior retinal arteries [Figure 1c]. It took the same time for fluorescein to flow from the superotemporal loop to the superotemporal branch retinal artery, suggesting slowed circulation within the arterial loops. The collateral running from the inferior branch macular artery to the occluded vessel was also visualised. The superonasal and the superotemporal branch retinal veins demonstrated delayed filling, presumably due to compression by the arterial loops. In contrast, the inferior tributaries of the central retinal vein filled normally. The venous phase in the superotemporal retina was delayed the most. The late phase of the angiogram showed partial filling of the proximal part of the occluded superior branch macular artery, presumably due to retrograde flow from the collateral [Figure 1d].

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Figure 1b:
Arterial phase of the fluorescein angiogram demonstrating the arterial nature of the two independent prepapillary loops (arrows). Early filling of the collateral is seen
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Figure 1c:
The early venous phase of the fluorescein angiogram shows complete filling of the collateral and perfusion of the distal portion of the occluded superior branch macular artery (curved arrow)
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Figure 1d:
The late phase of the fluorescein angiogram shows slight filling of the proximal portion of the occluded superior branch macular artery. The superotemporal vein is completely filled

The patient underwent an extensive physical examination and testing that included echocardiography, carotid Doppler, and laboratory investigations for collagen vascular and haematologic disorders. All the tests were within normal limits.

Discussion

Multiple prepapillary arterial loops have been reported in the literature, but only rarely.1 Moreover, while single prepapillary loops have been observed in association with inferior branch retinal arterial occlusions,234567 the occlusion of a superior branch retinal artery in a patient with a prepapillary arterial loop has not been reported. There has only been one case report of double prepapillary loops associated with what the authors presumed to be a congenitally regressed superotemporal branch retinal artery.1 This brief report describes double prepapillary arterial loops associated with a superior branch macular artery occlusion. To the best of our knowledge, this is the first case report of double prepapillary arterial loops associated with the occlusion of a superior retinal vessel.

Retinal artery occlusions in patients with prepapillary arterial loops are thought to be caused by slowed circulation within the loops secondary to anatomical kinking or twisting with the resultant raised hydrostatic pressure.34 The aetiopathogenesis of the retinal arterial occlusion observed in our case was most probably similar, as suggested by the angiographic demonstration of slowed circulation in the prepapillary loops. In addition, a transient increase in the intravenous pressure due to the bout of sneezing experienced by our patient could have resulted in a Valsalva-like mechanism which could have further raised the hydrostatic pressure in the loops. The superficial retinal haemorrhages in the territory of the occluded vessel could have resulted from transmission of the increased intramural pressure to the capillaries with resultant ischaemic endothelial damage.

Interestingly, previous studies have noted the decompensation of the prepapillary loops when subjected to an additional effect of a Valsalva-like mechanism. Brucker et al8 have noted vitreous haemorrhage in a young patient with prepapillary loops after he lifted heavy rocks. Regenbogen et al7 have postulated that occlusive processes of the arterial system in patients with prepapillary loops coupled with venous impairment (as occurs following a Valsalva-like mechanism) leads to production of vitreous haemorrhage. Our patient had an identical condition except for the fact that she had superficial retinal haemorrhages and not vitreous haemorrhage. The pathogenesis of these haemorrhages is however, similar as mentioned previously.

This report thus highlights the fact that patients with prepapillary loops are at an increased risk of retinal vascular decompensation if involved in activities that are associated with a Valsalva-like mechanism and hence need appropriate counselling in this regard.

1. Ding P, Chen M. Prepapillary arterial loops Retina. 1999;19:474–6
2. Bisland T. Vascular loops in the vitreous Arch Ophthalmol. 1953;49:514–29
3. Harcourt R, Locket N. Occlusion of a preretinal arterial loop Br J Ophthalmol. 1967;51:562–5
4. Brown GC, Magargal L, Augsberger JJ, Shields JA. Preretinal arterial loops and retinal arterial occlusion Am J Ophthalmol. 1979;87:646–51
5. Limaye SR, Tang RA, Pilkerton AR. Cilioretinal circulation and branch arterial occlusion associated with preretinal arterial loops Am J Ophthalmol. 1980;89:834–9
6. Degenhart W, Brown GC, Augsberger JJ, Magargal L. Prepapillary vascular loops Ophthalmology. 1981;88:1126–31
7. Regenbogen L, Godel V, Spierer A, Lazar M. Retinal arterial loop occlusion Ann Ophthalmol. 1981;13:729–32
8. Brucker AJ, Michels RG, Fine SL. Congenital retinal loops and vitreous haemorrhage Am J Ophthalmology. 1977;84:220–3

Proprietary Interest: None

Keywords:

Arterial occlusion; collateral; prepapillary loops

© 2005 Indian Journal of Ophthalmology | Published by Wolters Kluwer – Medknow