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Journal Français d'Ophtalmologie
Volume 39, n° 8
pages 711-715 (octobre 2016)
Doi : 10.1016/j.jfo.2016.07.005
Received : 5 Mars 2016 ;  accepted : 7 July 2016
Frequency of prepapillary vascular loops in Congolese patients
Fréquence des anses vasculaires papillaires chez les patients congolais
 

D. Kaimbo Wa Kaimbo
 Department of Ophthalmology, University of Kinshasa, Kinshasa, Democratic Republic of the Congo 

BP 16540 Kinshasa 1, Democratic Republic of the Congo.
Summary
Purpose

To determine the frequency of prepapillary vascular loops in the population of Congolese patients.

Methods

We performed a retrospective cross-sectional and descriptive analysis of the data collected between January 2005 and August 2014 from patients diagnosed with prepapillary vascular loops, in an outpatient eye clinic, a general ophthalmology practice.

Results

Out of 16,016 patients seen during the study period, 24 patients (27 eyes) were diagnosed with prepapillary vascular loops, for a frequency of 0.15%. The mean age of the patients with prepapillary vascular loops was 37.8 years±14 (SD) (range, 18 to 60 years). Male were more frequently diagnosed with prepapillary vascular loops than female (62.5% vs 37.5%). Unilateral prepapillary vascular loops were found in 77.8% and bilateral in 22.2% of eyes. Most of PPLs were estimated to be arterial (88.9% of eyes) based on clinical observation alone, as fluorescein angiography was not systematically performed. Ophthalmoscopically, the vessels appeared as simple (44.6%) or took more serial turns (corkscew or spiral-shaped) (55.6%). The average length of PPLs was 1.02mm (range 0.6 to 1.5mm) with an orientation (an axis orientation) in the superior nasal sector (50%), inferior nasal sector (33%) and superior temporal sector (17%); and a mean axis of 143° relative to the horizontal. Refractive errors were found in 16 eyes (59.3%) and included simple myopia (4 eyes, 14.8%), myopic astigmatism (8 eyes, 29.6%), hyperopic astigmatism (one eye, 3.7%), hyperopia (3 eyes, 11.1%); One patient (one eye, 3.7%) with high hyperopia had anisometropia. Primary open angle glaucoma was found in 5 (18.5%) eyes; vascular tortuosity was seen in two (7.4%) eyes. No complication such as retinal arterial occlusion, vitreous hemorrhage, or any other complication was found.

Conclusion

The frequency of 0.15% found in this study suggests that although rare, prepapillary vascular loops seem to be a bit more common in black people than in white and Asian people. An association between PPLs and refractive errors may be possible.

The full text of this article is available in PDF format.
Résumé
But

Déterminer la fréquence des anses prépapillaires (APP) chez les patients congolais.

Méthodes

Durant la période allant de janvier 2005 à août 2014, nous avons réalisé une étude transversale et descriptive des données des patients avec diagnostic d’APP, dans une clinique d’ophtalmologie générale.

Résultats

Sur un total de 16 016 patients examinés durant la période d’étude, 24 patients (soit 27 yeux) avaient un diagnostic d’APP, ce qui donne une fréquence relative de 0,15 %. L’âge moyen des patients avec APP était de 37,8ans ±14 (intervalle, 18 à 60ans). Les APP ont été diagnostiquées plus chez les hommes que chez les femmes (62,5 % vs. 37,5 %). L’atteinte a été unilatérale dans 77,8 % et bilatérale dans 22,2 %. La majorité des APP étaient classées artérielles (88,9 %) sur base de l’ophtalmoscopie. Les APP sont apparues simples (44,6 %) ou en tournevis (55,6 %). La longueur moyenne des APP a été de 1,02mm (intervalle, 0,5 à 1,5mm) avec une orientation dans le secteur nasal supérieur (50 %), dans le secteur nasal inférieur (33 %) et dans le secteur temporal supérieur (17 %) ; et un angle d’orientation de 143° par rapport à l’horizontale. Des vices de réfraction ont été retrouvés dans 16 yeux (59,3 %) et comprenaient une myopie simple (4 yeux, 14,8 %), un astigmatisme myopique (8 yeux, 29,6 %), un astigmatisme hypermétropique (un œil, 3,7 %) et une hypermétropie (3 yeux, 11,1 %). Un patient (un œil, 3,7 %) avec une hypermétropie forte a présenté une anisométropie. Le glaucome primitif à angle ouvert et la tortuosité des vaisseaux ont été retrouvés respectivement dans 5 yeux (18,5 %) et deux yeux (7,4 %). Aucune complication genre occlusion artérielle, hémorragie du vitré ou autre complication n’a été retrouvée (associée).

Conclusion

La fréquence d’APP de 0,15 % trouvée dans notre étude, suggère que bien que rare, l’affection semble être un peu plus fréquente chez les mélanodermes que chez les Caucasiens ou les Asiatiques. L’association entre vices de réfraction (astigmatisme) et APP pourrait être possible.

The full text of this article is available in PDF format.

Keywords : Prepapillary vascular loops, Frequency, DR Congo, Refraction, Black race, Central Africa

Mots clés : Anses vasculaires prépapillaires, Fréquence, République démocratique du Congo, Race noire, Afrique centrale


Introduction

Prepapillary vascular loops (PPLs) are congenital abnormalities (anomalies) characterized as blood vessels that project from the optic disc into the vitreous cavity and then return to the disc to continue their natural course [1]. Described for the first time by Liebrich in 1871 [2], PPLs formations are uncommon congenital vascular malformations and the majority is of arterial origin [3]. Although cases of PPLs have been reported in Caucasians and Asians [3, 4, 5, 6, 7, 8, 10, 11, 12, 13, 14, 15, 9], there is no data available on prevalence of PPLs in black Africa. The purpose of the study was to determine frequency of PPLs in Congolese patients from Central Africa.

Material and methods

We performed a cross-sectional and descriptive analysis of the data of the patients with PPL diagnosis. Data were collected between January 2005 and August 2014 in an outpatient eye clinic, a general practice of ophthalmology. The study was conducted according to the Helsinki Declaration. Patients received a complete ophthalmic examination which included visual acuity, refraction, slit-lamp examination of the anterior segment, Goldmann applanation tonometry, and indirect ophthalmoscopy. The refraction was determined by an objective refraction by automated refraction (using a Topcon RM 2000) that was refined by subjective refraction using a trial lens set. Because of the age of the study population, cycloplegia was not used for refraction. All refractive errors were converted to the spherical equivalent diopters by adding the spherical component of refraction to half of the cylindrical component. For this report, myopia was defined as a refractive error less than −0.50 D; hyperopia was defined as a refractive error greater than +0.50 D and emmetropia was defined as refractive error between +0.50 and −0.50 D. After a complete examination, the pupils were dilated with tropicamide 0.5% and phenylephrine 10% for funduscopy. The diagnosis of PPLs was based on ophthalmoscopic findings. The figure shows a fundus photography of a PPL in the right eye of one patient.

Results

Out of 16016 patients seen during the study period, 24 patients (27 eyes) were diagnosed with PPLs, giving a frequency of 0.15%. The mean age of the patients with PPLs was 37.8 years±14 (SD) (range, 18 to 60 years). Male were more frequently diagnosed with PPLs than female (62.5% vs 37.5%). Of 24 patients, 21 (87.5%) had PPLs in one eye (77.8%) and three (12.5%) patients had PPLs in the both eyes (22.2%).

Most of PPLs were estimated to be arterial (88.9% of eyes); the classification of these vascular anomalies as arterial or venous was based on clinical observation alone, as fluoangiography was not systematically performed. Ophthalmoscopically, the vessels appeared as simple (44.4%) or took more serial turns (corkscew or spiral-shaped) (55.6%) (Figure 1, Figure 2). The average length of PPLs was 1.02mm (range, 0.6 to 1.5mm) with an orientation (an axis orientation) in nasal superior sector (50%), nasal inferior sector (33%) and temporal superior sector (17%); and a mean axis of 143° relative to the horizontal (from the horizontal).



Figure 1


Figure 1. 

A fundus photography of a prepapillary arterial loop in the right eye of a 40-year-old patient.

Zoom



Figure 2


Figure 2. 

Fundus photographs of a 59-year-old man showing a bilateral and large prepapillary loop. Two ascending and descending branches are present. Temporal cilioretinal vessel can be seen (left).

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Refractive errors were found in 16 eyes (59.3%) and included:

simple myopia (4 eyes, 14.8%);
myopic astigmatism (8 eyes, 29.6%);
hyperopic astigmatism (one eye, 3.7%);
hyperopia (3 eyes, 11.1%).

One patient (one eye, 3.7%) with high hyperopia had anisometropia. Open angle glaucoma was found in 5 (18.5%) eyes; vascular tortuosity was seen in two (7.4%) eyes. No complication such as retinal occlusion, vitreous hemorrhage, or any other complication was found. Diabetes mellitus (one patient), prostatic adenoma (one patient) and gout (one patient) were systemic associated conditions found.

Discussion

Liebreich, in 1871 [2], first described the PPL, a congenital vascular anomaly that originates from a main branch of the central retinal artery on the optic disc [3, 7, 11, 15]. To the best of our knowledge, this study is the first to report PPLs in black patients from Central Africa. The population examined was recruited from an outpatient clinic and we found the frequency of PPLs to be 0.15%, approximately one in about 700 patients; this frequency found in this study is relatively high when compared to that reported in previous studies in Caucasians and Asians, ranging from one in 2000 to one in 9000 patients [3, 5, 7, 14].

In the study by Degenhart et al. [3], out of eighteen patients with PPLs, fourteen were black and four white. Our findings, together with the report of Degenhart et al. [3], suggest that PPLs could be more frequent in black than white patients. However, it is difficult to know the true prevalence of PPLs as most loops are asymptomatic and therefore remain either unseen or merely documented as a chance finding. All of our patients were asymptomatic on presentation and consulted for another problem, PPLs were diagnosed on routine examination. Population based studies based on systematic research of PPLs are necessary to determine the true prevalence of PPLs in black people.

Embryologically, the origin of PPLs if they are derived from the hyaloids or retinal arterial system has been debated [16]. Earlier hypotheses believed that the PPLs were remnants of the hyaloid artery. Hirschberg [17] suggested that PPLs are independent from the embryonic hyaloid's artery. Mann [11] hypothesized that the loops originate at about the 100mm embryonic stage (3.5–4months) at the time when retinal vascularization begins (developing). It has been proposed that the loop requires Bergmeister's papilla as a scaffold for growth and postulated that the retinal artery first extends forward within Bergmeister's papilla (glial tissue anterior to the optic nerve) instead of turning 90 degrees to grow radially onto the retina. When the Bergmeister's papilla atrophies (after regression of the surrounding glial tissue), the vessel loop is left protruding into the vitreous cavity. Thus, its growth is limited, since Bergmeister's papilla usually does not extend more than one third of the distance into the vitreous cavity. The origin of venous loops is thought to parallel that of arterial loops [11]. Two anatomic studies have supported the view of retinal arterial connection [15, 18]. Goldstein and Wexler studied prepapillary histopathologically and found them to be branches of the central retinal artery [15]. These preretinal arterial loops originate from a main branch of the central retinal artery on the optic disc. Histopathology demonstrates vessels without an internal classic lamina. The loops may be either arterial (83–95%) [19, 20] or venous and are independent from the embryonic hyaloids artery, as suggested by Hirschberg [17]. Shakin et al. [18] reported an anatomic study of prepapillary vascular loop that the latter communicated with the retinal arterial system and did not have an internal elastic lamina. Additionally, the connective tissue matrix of the vascular loop contained less hyaluronic acid than the vitreous. Their findings supported the embryologic deviation of prepapillary vascular loops from the retinal arterial system, rather than from the hyaloid artery because of the anatomic separation from the primary vitreous.

The clinical and fluorescein angiographic features of these vascular anomalies are well described in the literature [3, 7, 11, 13, 15, 16, 18, 21]. Though usually asymptomatic and are considered to be benign, they are usually detected incidentally on routine fundus examination. Visual acuity is usually normal unless events such as vitreous hemorrhage, branch retinal artery occlusion [22].

The loops have at least one ascending and one descending limb, and 85 to 95% are arterial in origin. The vessels may appear as simple hairpin loops (180° turns), in a figure eight, or in a corkscrew configuration. Occasionally, an arterial loop emerges from the disc and returns to the retina, whereas its venous counterpart may arise from the retina and exit into the disc. Rarely, a loop arises from the retina and returns to the retina; this particular anomaly has been termed a preretinal vascular loop [23].

In about 30% of cases, the loop is surrounded by a white, glial-appearing sheath [18]. The average arterial loop extends approximately 1.5mm into the vitreous cavity, probably within Cloquet's canal [3, 7]. The longest loop previously recorded was estimated to be 7.88mm long (in height) [16].

On fluorescein angiography, prepapillary loops demonstrate a rapid flow. However, there may be a sector delay in filling of the optic disc or the area of retina supplied by the loop caused by the increased distance that blood must travel through the loop. Fluorescein angiography demonstrates whether the loops are arterial or venous and if there is any relation to a cilioretinal artery. Cilioretinal arteries were most frequently reported in association with PPLs [3, 19, 22] and have been seen in up to 75% of eyes with prepapillary loops [3, 19, 22].

The anomaly has been reported to occur bilaterally in about 9 to 17% of cases of arterial loops, but the percentage with venous loops is uncertain [13]. We found bilaterally in 22.2% of our cases confirming that the PPLs are usually unilateral.

The differential diagnosis of PPLs includes persistent hyaloid artery, acquired venous loops, neovascularization of the optic disc. A persistent hyaloids artery should not be confused with a prepapillary loops. The hyaloids artery is a simple vessel that extends anteriorly to the posterior lens capsule, without ascending and descending branches. Congenital venous prepapillary loops must be differentiated from the acquired variety [24]. Congenital loops usually are single and unassociated with other ocular abnormalities, whereas acquired venous loops usually are multiple, and referred to as optociliary collateral vessels, and are seen with disease entities such as retinal venous obstruction and optic nerve tumors [25]. Neovascularization of the optic disc can occasionally mimic a PPL when it extends into Cloquet's canal. Neovasclarization is typically associated with abnormalities such as diabetic retinopathy, retinal venous obstruction and the ocular ischemic syndrome resulting from carotid artery obstruction. Neovascularization of the disc leaks on fluorescein angiography, but prepapillary loops do not leak fluorescein.

No consistently associated systemic abnormalities have been found in conjunction with prepapillary loops. In our study, PPLs were associated with refractive errors in 59.3% of eyes; refractive errors included myopic astigmatism (29.6%), simple myopia (14.8%), hyperopia (11.1%). Mireskandari et al. reported a case of a 21-year-old female with unilateral PPLs and high myopia of 10 diopters in both eyes [16]. The association of PPLs and refractive errors found in our study, especially with astigmatism has not been reported. It could probably be a fortuitous association or a link between the different conditions. In our study, open angle glaucoma was found in 18.5% of eyes with PPLs.

Ocular complications associated with prepapillary vascular loops include branch retinal artery obstruction in the area of retina supplied by the loop (in the sector of the retina supplied by the loop), the major complication [3, 19]. Approximately 10% of cases of loops reported have been associated with arterial obstruction. The mechanisms of occlusion of the PPLs are not clear. Some authors have postulated a mechanical effect secondary to the spiral makeup of the loop leading to increased turbulence or torsion especially in association with posterior vitreous detachment (slowed circulation within the loops secondary to anatomical kinking or twisting with the resultant raised hydrostatic pressure).

Other complications reported included amaurosis fugax, vitreous hemorrhage, particularly in association with posterior vitreous detachment, persistent hyperplastic primary vitreous [9], choroidal veins tortuosity [3, 26, 27, 28].

In summary, this study reports a higher frequency of 0.15% (one out of 700 patients) of PPLs when compared with frequencies reported previously in Caucasians and Asians (one out of 2000 to 9000 patients). Refractive errors (astigmatism) seem to be associated with PPLs. Further studies are needed.

Disclosure of interest

The author declares that he has no competing interest.


 Le texte a fait l’objet d’une présentation orale lors du 121e congrès de la Société française d’ophtalmologie à Paris.

References

Mitchell P.R., Fineman S., Brown G.C. Congenital fundus abnormalities. Chapter 8 Duane's clinical of ophthalmology : CD Rom Edition (2006). 
Liebrich R. Demonstration of diseases of the eye: persistent hyaloid artery and vein Trans Pathol Soc Lond 1871 ;  22 : 221
Degenhart W., Brown G.C., Augsberger J.J., Magargal L. Prepapillary vascular loops Ophthalmology 1981 ;  88 : 1126-1131 [cross-ref]
Ashton N. The mode of development of the retinal vessels in man William MacKenzie Centenery Symposium on the Ocular Circulation in Health and Disease St Louis, CV: Mosby (1969).  7-17
Awan K.J. Arterial vascular anomalies of the retina Arch Ophthalmol 1977 ;  95 : 1197
Barishak Y.R. Embryology of the eye and its adnexae Dev Ophthalmol 1992 ;  24 : 1
Brown G.C., Tasman W.S. Congenital anomalies of the optic disc  New York: Grune & Stratton (1983). 
Ding P., Chen M. Prepapillary arterial loops Retina 1999 ;  19 : 474-476
Makino S., Ohkubo Y., Tampo H. Prepapillary vascular loop associated with persistent hyperplastic primary vitreous Case Rep Ophthalmol Med 2013 ;  2013 : 259797
Mann I. Development of the human eye  New York: Grune & Stratton (1969). 
Mann I. Developmental abnormalities of the eye  Philadelphia: JB Lippincott (1957). 
Oxilia E. Anomalie vascolari della retina: ansa arteriosa prepapillare Ann Ophthalmol Clin Ocul 1946 ;  73 : 408
Romano P.E. Prepapillary vascular loops Clin Exp Ophthalmol 2001 ;  29 : 90-91 [cross-ref]
Makino S. Prevalence of prepapillary vascular loop Sch J App Med Sci 2015 ;  3 : 693-694
Goldstein I., Wexler D. The pre-retinal artery. An anatomical study Arch Ophthalmol 1929 ;  11 : 324-334 [cross-ref]
Mireskandari K., Bentley C., Aclimandos W.A. Bilateral prepapillary loops with unilateral branch retinal artery occlusion following thrombus at the loop apex Retina 2001 ;  21 : 66-67 [cross-ref]
Hirschberg J. Ein Fall von prapäpillarer Gefässchlinge der Netzhautschlagader Zentralbl Prakt Augenheilkd 1885 ;  9 : 205
Shakin E.P., Shields J.A., Augsburger J.J., Brown G.C. Clinicopathologic correlation of a prepapillary vascular loop Retina 1988 ;  8 : 55
Brown G.C., Magargal L., Augsberger J.J., Shields J.A. Preretinal arterial loops and retinal arterial occlusion Am J Ophthalmol 1979 ;  87 : 646-651 [cross-ref]
Bisland T. Vascular loops in the vitreous Arch Ophthalmol 1953 ;  49 : 514-529
Kritzinger E.E., Beaumont H.M.A. Colour atlas of optic disc abnormalities  Baltimore: Wolf Year Books (1987). 38-39
Limaye S.R., Tang R.A., Pilkerton A.R. Cilioretinal circulation and branch arterial occlusion associated with arterial loops Am J Ophthalmol 1980 ;  89 : 834-839 [cross-ref]
Brown G.C., Annesley W.H., Magargal L.E. Peripheral venous loop Retina 1981 ;  1 : 290
Wygnanski-Jaffe T., Desatnik H., Treister G., Moisseiev J. Acquired prepapillary vascular loops Arch Ophthalmol 1997 ;  115 : 1329[letter].  [cross-ref]
Bronner A., Risse J.F., Flament J. Prepapillary vascular looping and thrombosis of the retinal central vein: discussion and observations [in French] Rev Oto Neuro Ophtalmol 1976 ;  48 : 249
Giuffré G., Lodato G. Prepapillary venous loops and choroidal vein s tortuosity Acta Ophthalmolol Scand 2003 ;  81 : 665-666
Strassman I.B., Desai U.R. Prepapillary vascular loop and a recurrent vitreous hemorrhage Retina 1997 ;  17 : 166
Soltau J.B., Olk R.J., Gordon J.M. Prepapillary arterial loop associated with vitreous hemorrhage and venous retinal macrovessel Retina 1996 ;  16 : 74 [cross-ref]



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