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ARTICLES
Year : 1972  |  Volume : 20  |  Issue : 4  |  Page : 141-144

Vessels at the disc margin (cilioretinal and other simulating cilioretinal vessels)


Department of Ophthalmology, Postgraduate Institute of Medical Education and Research, Chandigarh, India

Correspondence Address:
I S Jain
Department of Ophthalmology, Postgraduate Institute of Medical Education and Research, Chandigarh
India
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Source of Support: None, Conflict of Interest: None


PMID: 4671303

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How to cite this article:
Jain I S, Singh K, Nagpal K C. Vessels at the disc margin (cilioretinal and other simulating cilioretinal vessels). Indian J Ophthalmol 1972;20:141-4

How to cite this URL:
Jain I S, Singh K, Nagpal K C. Vessels at the disc margin (cilioretinal and other simulating cilioretinal vessels). Indian J Ophthalmol [serial online] 1972 [cited 2021 Mar 4];20:141-4. Available from: https://www.ijo.in/text.asp?1972/20/4/141/34648

Table 1

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Table 1

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  Introduction Top


LANG AND BARRET [7] defined a cilioretinal artery as the one which dips into the nerve near the margin of the optic disc and which can be seen to arch outwards. They did not regard a vessel without this curve as cilioretinal. SALZMANN [12] and DUKE ELDER [4] also described this sharp loop as a diagnostic feature of the cilioretinal- artery. These authors did not comment about the other vessels which may be seen to be coming out near the disc margin or just inside the margin. Whether these vessels are branches of central retinal artery or of posterior ciliary arteries is not quite a settled question.

The incidence of cilioretinal arteries has been reported to vary from being 'exceptional' (DUKE ELDER) [3] to "so common" (MANN) [10] .

SALZMANN [13] reported the disappea­rance of cilioretinal arteries in his own eyes with age and believed that the process was similar to the dis­appearance of the hyaloid artery. If this were really so, then a difference in the incidence of cilioretinal arteries in the young and the old should be marked. To verify this, a detailed study regarding these vessels was undertaken.


  Material and Methods Top


A thorough ocular survey of the total population of 921 people living in 3 villages near Chandigarh' was undertaken. The fundii were examin­ed in detail with special emphasis on the vessels originating at or just inside the disc margin, the nature of the vessels (whether arterial or venous), their size as compared to the branches of the central retinal artery (small, medium or large) and their distribu­tion and branching pattern (whether they divided nasal or temporal to the macula).


  Observations Top


Out of the 921 persons examined, 515 were males and 416 females. The examined male and female dis­tribution (0.548 : 0.452 is almost in the same proportion as the popula­tion distribution (0.536:0.462).

Cilioretinal artery was observed in 210 persons as against only two, per­sons who showed corresponding cilioretinal vein. The general incidence found was 22.8% [Table - 1].

In the male population this was encountered in 22.3% while in the females 23.4%. The incidence was highest in the second decade in either sex. Taking the total population as a whole the incidence was seen to fall progressively from 2nd decade on­wards after showing a rise from 1st decade to 2nd decade, the slight rise in the 6th decade in males and in the 5th decade in females may - be considered insignificant.

Amongst the persons having cilioretinal artery, its distribution was noticed to be common in the upper temporal region (37.8%). Next in frequency was lower temporal 27.8%, direct temporal 30.8% and nasal 3.6%. This pattern was maintained in almost all the decades.

In three persons the vessels were seen to originate from lower temporal region and after crossing the macula got distributed to the upper temporal region.

Unilateral cases were more than bilateral in the ratio of 3:2. This relationship was maintained in almost all the age groups. Unilaterality was slightly more common in females 15% as against 12.6% in males, while bilaterality was 9.7% in males and 8.1% in females.

As far as the distribution pattern of the branches was concerned, it was `nasal to macula' in 30.6% `temporal' to macula in 45.8%, while it was combined (both nasal and temporal to macula) in 23.6%.

In 3.1% of the total population moer than one branch was encountered. These were noticed in the first and second decades only. In the other decades, there was only one vessel present.

The vessels were large in size in 28.4% medium in 37.8% and small in 34.8%.

As the age advanced the size showed a progressive decrease, so much so, that after the 5th decade there was hardly any big vessel present. In the 5th decade only two large vessels were observed. In one patient it was seen only in one eye and that eye had a long standing glaucoma. The vessel was unusually large, in that patient for his age.

There was no special predilection noticed for right or left eye.

The distribution between right (64) and left (63) eyes in all the age groups was about equal.


  Discussion Top


The reported incidence of ciliore­tinal arteries varies from author to author (6.9% - 25%). MANN [10] pointed out that it was so common that its existence in man may be regarded as normal, while BLUNT [1] found no cilioretinal artery in 72 eyes studied anatomically.

In the present series we had an overall incidence of 22.8%. This figure was roughly in agreement with the figures reported by many other authors (LORENTZEN [8] 26%, COLLIER [2] 21.6%). However, it was in striking contrast to the figure of 6.9% reported by MEHRA [11] from India. Taken in terms of eyes involv­ed, we observed these vessels in 15.9% of the eyes examined. Corres­ponding figures available from other authors are 15% (LORENTZEN [8] , 4% MEHRA [11] , 12.5% COLLIER [2] , 17% SALZMAN [12] and 19.1% JACKSON [6] ). Considering decade wise, it was observed that the maximum incidence was seen in the second decade and then there was a gradual decline, it being least common in 5th and 6th decades, and later. We feel that the presence and disappearance of the vessel, as is clear from the falling incidence, should be seen in the light of retinal need rather than implying that these vessels are atavistic in nature (MANN [9] SALZMANN [13] ). The mere rise in percentage from 1st to second decade, viz: from 24.4% to 32.2% is inconsistent with its atavistic nature. This is also inconsistent with the contention of HEYREH [13] that cilioretinal artery is just a congenital anomaly, as this also cannot explain the increase in the second decade and subsequent fall with age. It does not imply that these vessels are formed anew at a later stage. However, the possibility of some defunct vessels getting opened up later cannot be ruled out. The observation that these vessels may replace branches of central retinal artery does seem to indicate that the appearance and fate of these vessels is nutritionally oriented. The relative anoxia during development might be a stimulus for this to develop and so help the macular nutrition. The decreasing retinal need with age, might, there­fore, be responsible for the subse­quent disappearance. This latter contention has been supported by the observation in a patient of unilateral glaucoma 45 years old, where the artery was present only in the glaucomatous eye. The artery was as thick as could be expected in a young individual. The reason for this lack of disappearance might presumably be the need of the retina. This theory, however, does not explain the absence of the vessel in the large majority, having strangulat­ed retinal pathologies.

As regards the distribution pattern of these vessels, our findings are in conformity with those described by COLLIER [2] . The common pattern encountered by the author was superior temporal distribution. Then in order of frequency were infero­temporal, macular superior nasal and lastly infero-nasal. In our series the pattern of distribution has been in the following order: supero-temporal, direct-temporal, infero-temporal and nasal. Except this frequency reversal in the distribution of macular and inferior temporal vessels, our findings are in agreement with COLLIER'S [2] . One peculiar observation made by us was that in three cases the cilioretinal vessel originated in one quadrant of the optic disc and was distributed to the opposite quadrant.

The branching pattern of these vessels has not been described by earlier workers. Most of the macular (direct temporal) vessels showed branching nasal to the macula while the upper temporal and the lower temporals divided either before or after the macula was crossed. The significance of this peculiar branching pattern remains speculative.

In unilateral cases the predilection for right and left eyes has been variously reported; some authors re­port it to be more common on the left side (COLLIER [2] ) 60% on left side or equal on the two sides (JACKSON [6] ). We found the incidence to be almost equal on the two sides. The number of cilioretinal vessels in one eye has been reported to vary from one to three (JACKSON [6] ). In our series it was one vessel only in 96.9% of the cases and more than one vessel in 3.1%.

The cilioretinal vein was again a rarity in our series. We observed only two cases with cilioretinal vein. That again leads us to assume that cilioretinal artery is a part of the general macular blood supply and as the drainage with the rest of retina is efficient, the necessity of the ciliore­tinal vein is obviated.


  Summary and Conclusions Top


22.8% of the 921 persons residing in villages in the vicinity of Chandigarh were found to have cilioretinal artery. The corresponding vein was en­countered in 0.217% only. The incidence was highest in the second decade in either sex. The commonest distribution was in the "upper temporal", next being "lower temporal", "direct temporal" and "nasal" in that order. Unilateral cases were more than bilateral in the ratio 3:2, unilaterality being common in females. Branching pattern "temporal to macula" was common. The significance of these vessels is discussed. It is surmised that their appearance and fate is nutritionally orientiated rather than these being atavistic remmants.

 
  References Top

1.
Blunt, M. N.: Implications of the vascular anatomy of the optic nerve and chiasma. Proc. Roy Soc. Med. 49: 433 (1956).  Back to cited text no. 1
    
2.
Collier, M.: Bull. Soc. Ophthal. Trac. 598, 60 (1957).  Back to cited text no. 2
    
3.
Duke Elder, S.: Text book of Ophthalmology H. Kimpton London 1938. Vol. II, p. 1389.  Back to cited text no. 3
    
4.
Duke Elder, S.: Text book of Ophthalmology H. Kimpton London 1938 Vol. 1. p. 1949.  Back to cited text no. 4
    
5.
Heyreb, S. S.: The cilioretinal arteries. Brit. J. Ophthal. 47: 71-89, (1963).  Back to cited text no. 5
    
6.
Jackson, E.: Cilioretinal and other retinal vessels. Ophthal. Rev. 30: 264 (1911).  Back to cited text no. 6
    
7.
Lang, W. and Barret, J. W.: On the frequency of cilioretinal vessels and of pulsating veins. Roy. London. Ophthal. Hosp. Rep. 12: 59, 1889. Quoted by: Lorentzen, S. E. Acta Ophthalmologica, 48: 518, 1970.  Back to cited text no. 7
    
8.
Lorentzen, S. E.: Incidence of cilioretinal arteries Acta Ophthal­mologica, 48: 518-525 (1970)  Back to cited text no. 8
    
9.
Mann, I.: The development of the human Eye. University Press, Cambridge, 233 (1928).  Back to cited text no. 9
    
10.
Mann, I: Developmental abnor­malities of the eye IInd ed. p. 136 BMA Lond. 1957.  Back to cited text no. 10
    
11.
Mehra, K. S.: The incidence of cilioretinal arteries in Indians. Brit. J. Ophth. 49: 52-53 (1965)  Back to cited text no. 11
    
12.
Salzmann, M.: The anatomy and histology of human eyeball in the normal state. Its development and senescence. Trans. Evl. Brown Chicago, 183, 1912.  Back to cited text no. 12
    
13.
Salzmann, M.: V. Graef Arch Ophth. 153: 451 (Ophthal Lit. London) 7: 308, 1953. (Quoted by): Heyreh, S. S.: The cilioretinal arteries Brit. J. Ophthal. 47: 17: 1963.  Back to cited text no. 13
    



 
 
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Introduction
Material and Methods
Observations
Discussion
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