Central retinal vein occlusion caused by anomalous prepapillary venous loop

Pradeep Gajanan Tekade; HN Ravishankar; Pradeep Sagar

doi:10.4103/jcor.jcor_28_20

Users Online: 353

BRIEF COMMUNICATION

Year : 2021 | Volume : 9 | Issue : 1 | Page : 32-34

Central retinal vein occlusion caused by anomalous prepapillary venous loop

Pradeep Gajanan Tekade¹, HN Ravishankar², Pradeep Sagar²
¹ Vitreoretinal Services, Mahatme Eye Hospital and Eye Bank, Nagpur, Maharashtra; Vitreoretinal Services, Sankara Eye Hospital, Shimoga, Karnataka, India
² Vitreoretinal Services, Sankara Eye Hospital, Shimoga, Karnataka, India

Date of Submission	23-Mar-2020
Date of Decision	23-May-2020
Date of Acceptance	02-Nov-2020
Date of Web Publication	10-Apr-2021

Correspondence Address:
Pradeep Sagar
C/o NR Ekhar, First Floor, Plot No. 109, Rajeev Nagar, Somalwada, Nagpur - 440 025, Maharashtra
India

Source of Support: None, Conflict of Interest: None

Check

DOI: 10.4103/jcor.jcor_28_20

Abstract

We present a case of prepapillary venous loop complicated by central retinal vein occlusion (CRVO). A 56-year-old female reported to us with blurring of vision in the right eye, noticed 8 days ago. Fundus examination in the right eye showed multiple superficial retinal hemorrhages in all the four quadrants with dilated veins and cystoid macular edema, suggestive of CRVO. Prepapillary venous loops were seen in both the eyes. In our case, both the eyes had an abnormal venous anatomy at the disc. On fundus fluorescein angiography, only the looped segment showed laminar flow in late phase in both the eyes. Hence, patients with an abnormal retinal venous anatomy should be treated with caution as they are considered to be at a high risk of retinal vein occlusion.

Keywords: Central retinal vein occlusion, prepapillary loop, retinal vein occlusion

How to cite this article:
Tekade PG, Ravishankar H N, Sagar P. Central retinal vein occlusion caused by anomalous prepapillary venous loop. J Clin Ophthalmol Res 2021;9:32-4

How to cite this URL:
Tekade PG, Ravishankar H N, Sagar P. Central retinal vein occlusion caused by anomalous prepapillary venous loop. J Clin Ophthalmol Res [serial online] 2021 [cited 2022 Jun 26];9:32-4. Available from: https://www.jcor.in/text.asp?2021/9/1/32/313472

Prepapillary vascular loop (PPL) is a variant of the normal retinal vasculature seen on and around the optic disc. PPL was first described by Liebrich in 1871 and is a well-recognized phenomenon. Its prevalence is estimated at 1:2000–1:9000, but this is likely to be an underestimate as many patients with PPL are asymptomatic.^{[1],[2],[3],[4],[5]} PPLs have been reported to be associated with branch retinal artery occlusion (BRAO), amaurosis fugax, recurrent vitreous hemorrhage, subretinal hemorrhage, and hyphema.^{[6],[7],[8],[9],[10],[11]} We report a case of central retinal vein occlusion (CRVO) possibly due to prepapillary venous loop with anomalous central retinal vein.

Case Report

A 56-year-old female reported to us with blurring of vision in the right eye, noticed 8 days ago. Her vision in the left eye was poor since childhood. She was a known diabetic for 8 years and was controlled under oral antidiabetic medications. Her best-corrected visual acuity (BCVA) was 20/600 in the right eye and 20/40 in the left eye. Intraocular pressure was 16 mmHg in the right eye and 14 mmHg in the left eye. Fundus examination in the right eye showed multiple superficial retinal hemorrhages, microaneurysm in all the four quadrants with dilated veins, and cystoid macular edema, suggestive of CRVO associated with nonproliferative diabetic retinopathy. Dot-blot hemorrhages and microaneurysms were seen in the left eye, suggestive of nonproliferative diabetic retinopathy. Prepapillary venous loops were seen in both eyes [Figure 1]a, [Figure 1]b and [Figure 2]a, [Figure 2]b. Upon closer observation, veins at the disc had an abnormal course. In the right eye, the vein draining the inferotemporal quadrant of the retina looped and communicated with the vein draining the inferonasal quadrant to form a trunk. This trunk formed a loop and communicated with the vein from the superonasal quadrant and eventually drained into the central retina vein. The superior branch of the central retinal artery was running over this trunk and the superotemporal vein. Similar course was seen in the left eye.

Figure 1: (a) The right eye showing neurosensory detachment with intraretinal cysts, Pre injection OCT showing macular edema, (b) Post injection Edema resolved, (c,d) FFA showing staining of vessel wall in late phase at vascular loop (yellow arrow)

Click here to view

Figure 2: In both eyes, (a,b) the vein draining the inferotemporal quadrant of the retina looped and communicated with the vein draining the inferonasal quadrant to form a trunk (white arrow) .This trunk formed a loop and communicated with the vein from the superonasal quadrant and eventually drained into the central retina vein. Black arrow (c,d) FFA showing laminar flow in trunk (yellow arrow)

Click here to view

On optical coherence tomography, the right eye showed neurosensory detachment with intraretinal cysts. The patient received intravitreal injection of bevacizumab 1.25 mg [Figure 3]a. BCVA improved to 6/18 with resolution of macular edema at 1 month post injection [Figure 3]b. Fundus fluorescein angiography (FFA) was performed after partial resolution of retinal hemorrhages. FFA showed delayed arteriovenous transit, microaneurysms, and blocked fluorescence, corresponding to retinal hemorrhages. The looped segment showed staining of the vessel wall in the late phase, indicating stasis. Routine blood investigation including complete blood count, lipid profile, blood sugar levels, and serum homocysteine was done to rule out other causes of CRVO. Routine blood investigation came to be within normal limits.

Figure 3: The right eye showing neurosensory detachment with intraretinal cysts, with resolution of macular edema at 1 month post injection. (a) Pre injection OCT showing macular edema, (b) Post injection Edema resolved

Click here to view

Discussion

The majority of PPLs are thought to be congenital in origin.^[12] Approximately 95% of the prepapillary loops are arterial based on FFA findings, and loops of venous origin are extremely rare.^[12],[13]

Thrombus formation within the lumen of the central retinal vein near the lamina cribrosa is the main mechanism responsible for CRVO. The vessels are located within a common adventitial sheath at the level of lamina cribrosa. This crowded environment may predispose to arteriolar compression of the distal central retinal vein, leading to endothelial damage, turbulent blood flow, and thrombus formation with subsequent edema.^[14],[15] CRVO is reported to occur in young patients with anomalous retinal vascular anatomy at the level of the optic nerve head. The proposed mechanism was a combination of turbulent flow, increased intravascular volume, and pressure from the arteriolar side of the circulation, causing a mechanical mass effect on the venous side.^[16] In our case, both the eyes had an abnormal venous anatomy at the disc. On FFA, only the looped segment showed laminar flow in the late phase in both the eyes [Figure 1] and [Figure 2]. This suggested a sluggish flow in this segment. Other systemic factors such as arteriosclerosis and diabetes mellitus would have contributed to CRVO in this case. However, the abnormal venous anatomy would have led to the sluggish flow, which could have increased the risk of CRVO. Hence, patients with an abnormal retinal venous anatomy should be treated with caution as they are considered to be at a high risk of retinal vein occlusion.

Previously, complications such as BRAO, amaurosis fugax, recurrent vitreous hemorrhage, subretinal hemorrhage, and hyphema are reported in prepapillary loop. To our knowledge, CRVO was not reported as a complication along with prepapillary venous loop, which is rare.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

References

1.	Liebrich R. Demonstration of diseases of the eye: Persistent hyaloid artery and vein. Trans. Pathol Soc Lond 1871;22:221.
2.	Kritzinger EE, Beaumont HM. A Colour Atlas of Optic Disc Abnormalities. Baltimore: Wolf Year Books; 1987. p. 38-9.
3.	Goldstein I, Wexler D. The pre-retinal artery. An anatomical study. Arch Ophthalmol 1929;11:324-34.
4.	Shakin EP, Shields JA, Augsburger JJ, Brown GC. Clinico-pathological correlation of a prepapillary vascular loop. Retina 1998;8:55-8.
5.	Brown GC, Asman WS. Congenital Anomalies of the Optic Disc. New York: Grune and Stratton; 1983. p. 31-57.
6.	Brucker AJ, Michels RG, Fine SL. Congenital retinal arterial loops and vitreous hemorrhage. Am J Ophthalmol 1977;84:220-3.
7.	Misra A, Flanagan DW, Martin KR. Recurrent transient visual loss due to intermittent occlusion of a prepapillary vascular loop. Br J Ophthalmol 2008;92:431-2.
8.	Fujiwara T, Machida S, Herai T, Tazawa Y. Case of subretinal hemorrhage that developed from a prepapillary vascular loop. Jpn J Ophthalmol 2004;48:175-7.
9.	Strassman IB, Desai UR. Prepapillary vascular loop and a recurrent vitreous hemorrhage. Retina 1997;17:166-7.
10.	Brown GC, Magargal L, Augsburger JJ, Shields JA. Preretinal arterial loops and retinal arterial occlusion. Am J Ophthalmol 1979;87:646-51.
11.	Limaye SR, Tang RA, Pilkerton AR. Cilioretinal circulation and branch arterial occlusion associated with preretinal arterial loops. Am J Ophthalmol 1980;89:834-9.
12.	Degenhart W, Brown GC, Augsburger JJ, Magargal L. Prepapillary vascular loops. Ophthalmology 1981;88:1126-31.
13.	Teramoto S, Ohno-Matsui K, Tokoro T, Ohno S. Bilateral large peripapillary venous and arterial loops. Jpn J Ophthalmol 1999;43:422-5.
14.	Green WR, Chan CC, Hutchins GM, Terry JM. Central retinal vein occlusions: A prospective histopathologic study of 29 eyes in 28 cases. Retina 1981;1:27-55.
15.	Hayreh S. Prevalent misconceptions about acute retinal vascular occlusive disorders. Prog Retin Eye Res 2005;24:493-519.
16.	Schatz H, Chang LF, Ober RR, McDonald HR, Johnson RN. Central retinal vein occlusion associated with retinal arteriovenous malformation. Ophthalmology 1993;100:24-30.