Congenital preretinal arterial loop: Is it a misnomer?

We describe a case of recurrent spontaneous vitreous haemorrhage due to congenital retinal arterial loop. The pre-optical coherence tomography showed the loop to be intraretinal rather than pre retinal. Thus the term pre retinal arterial loop is a misnomer. The arterial loop is in the superficial layer of retinal nerve fiber layer. We also demonstrated preretinal posterior hyaloid tissue attached on the retinal arterial loop, which may be the cause of traction and spontaneous recurrent VH.

Introduction

Congenital preretinal arterial loop is a vascular anomaly, in which the main branch of central retinal artery forms a preretinal arterial loop near the optic disc. Congenital retinal loop near the disc has been described as uncommon causes of spontaneous vitreous hemorrhage (VH).[1] Many authors have described it as preretinal arterial loop.[234] However, these descriptions are in pre-optical coherence tomography (OCT) era. We describe a case of recurrent spontaneous VH resulting from congenital retinal arterial loop, which was later confirmed to be intraretinal on OCT rather than preretinal.

Case Report

We report a case of an 11-year-old boy, who was seen in 2005, complains of floaters in the left eye. He had no history of systemic illness or Valsalva maneuver. On examination, his best-corrected visual acuity (BCVA) was 6/6, N6 in both the eyes. Intraocular pressure (IOP) and anterior segment were unremarkable. Fundus examination revealed normal in the right eye, while tortuous retinal vessel loop near the superior portion of the disc with surrounding retinal hemorrhage and minimal diffuse VH in the left eye. There was no posterior vitreous detachment. Fundus fluorescein angiography (FFA) of the left eye showed prominent arterial loops superior to the disc in the peripapillary area. There was no abnormal blood flow in the arterial loop. The angiogram showed no dye leakage from the arterioles or from adjacent capillary bed. He again presented to us in August 2013 with similar complaints in the left eye. He gave a past history of similar attacks of left eye floaters in 2007, 2012, and February 2013, was diagnosed as VH and treated conservatively. On examination, his BCVA, IOP, and anterior and posterior segment examinations were same as before.

Figure 1 shows the fundus and FFA images of the left eye showing preretinal arterial loop in superior peripapillary area. Figure 2 shows the OCT through the retinal arterial loop in the left eye superior to the disc showed that both superficial and deep components of retinal arterial loop were within the retina (retinal nerve fiber layer [RNFL]). There was a posterior hyaloid attached to the loop causing traction [Figure 3].

Figure 1

Fundus and fluorescein angiography image showing arterial loop

Figure 2

Optical coherence tomography showing back shadowing due to retinal arterial loop

Figure 3

Optical coherence tomography showing traction on the retinal arterial loop

Discussion

In 1871, preretinal arterial loops were first described by Liebrich.[3] Goldstin and Wexler[4] showed that retinal arterial loops are segmental anomalies involving a branch of the central retinal artery. Complications such as branch arteriole occlusion and spontaneous VH after strenuous activity have been reported along with congenital retinal loops.[2] VH due to vascular loops was usually mild because they act as low-flow, high-pressure system. Hence, the amount of VH is less, and it undergoes spontaneous resolution; rarely, it may be recurrent and may require pars plana vitrectomy.[1]

The exact location of the loop as described previously was preretinal.[2345] The major retinal arteries near the disc remain in the RNFL. In our case, OCT clearly demonstrates that the major retinal vessels are in the RNFL and retinal arterial loop was also in superficial layer of RNFL. OCT also shows preretinal posterior hyaloid tissue attached on the retinal arterial loop, which may be the cause of traction and spontaneous recurrent VH.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.