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ARTICLES
Year : 1981  |  Volume : 29  |  Issue : 4  |  Page : 459-462

Methods of study of aqueous veins


Gurunanak Eye Centre, Maulana Azad Medical College, New Delhi, India

Correspondence Address:
J D Batra
Gurunanak Eye Centre, Maulana Azad Medical College, New Delhi
India
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Source of Support: None, Conflict of Interest: None


PMID: 7346478

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How to cite this article:
Batra J D, Patnaik B, Kalsi R, Singh G, Jain B S, Aggarwal D P. Methods of study of aqueous veins. Indian J Ophthalmol 1981;29:459-62

How to cite this URL:
Batra J D, Patnaik B, Kalsi R, Singh G, Jain B S, Aggarwal D P. Methods of study of aqueous veins. Indian J Ophthalmol [serial online] 1981 [cited 2020 Jun 3];29:459-62. Available from: http://www.ijo.in/text.asp?1981/29/4/459/30954

Table 1

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Table 1

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Following Ascher's description of aqueous veins in 1942 as vessels containing either colourless fluid or diluted blood or both and intercalated between Schelemm's canal and conjunctival or episcleral veins and his exten­sive investigations on these in the fiftees, the interest in their study had been confined to the very serious among the students of Ophthalmology. However lately the interest in aqueous veins has been revived coinciding with the growing popularity of trabeculectomy as a glaucoma operation.


  Method and material Top


1. Simple slit lamp examination

Twenty eyes were examined by a Haag Streit slit lamp-900 with white light, red-free (green light) illumination under IOX, and 16X magnification. Both diffuse and focal illumination used. While the blood vessels around the limbus were being observed through the slit lamp to detect any aqueous veins, the globe was pressed intermittently through the lower lid to induce changing of patterns aqueous flow.

2. Local Instillation of Fluorescein

In 10 eyes of this group, 1 drop of 2% sodium fluorescein solution was instilled every minute for 5 minutes. The conjunctival sac was irrigated with normal saline. The eyes were examined with a slit lamp using a cobalt blue filter while the lamp supercharged with 7.5 volts. To improve fluorescence perception the observer dark adapted himself for 30 to 45 minutes in a dark room.

The eyes were examined at every 10 minu­tes interval for 30 minutes and at 20 minutes interval thereafter.

3. Intravenous Technique

All the 16 eyes were examined by the slit lamp as above at every 10-20 minutes interval starting 30 minutes after injecting 5 ml. of 10% or 20% sodium fluorescein solution intravenously-till no new information could be had. At suitable interval fluorescence photog­raphs were taken using preplanned camera settings on a photo slit lamp optical system and flash illumination and the Robot camera of the fluorescein fundus camera of Zeiss (West Germany)

4. Intracameral Technique

In the operation theatre, after surface anaesthesia with 4% xylocain facial block and retrobulbar injection of xylocain was given. A scratch incision was made obliquely starting 2-3 mm behind the limbus. In either case about 2/3rd thickness of cornea was incised. Then the anterior chamber was entered with a sharp 26 gauze short stem needle fitted to a tuberculin syringe, contain­ing 0 5 ml of sodium fluorescein. Nearly 0.15 ml of the solution was then injected and the needle withdrawn. A small amount of dye leaked out is thoroughly washed away. The globe was then examined for aqueous veins while intermittent digital pressure was applied on the globe. Solution used : 0.1 % in 2 eyes 0.2% in 4 eyes. 0.3% in 1 eye.


  Observations Top


Simple slit lamp examination

Aqueous veins could be detected in 8 out of the 20 eyes examined with white light. Redfree (green) light has no advantage.

Local instillation of Fluorescein.

The cornea, perhaps also aqueous, acqui­red some fluorescence. But this was of little use in identification of the aqueous veins.

Intravenous Injection

The dye gives a greenish hue at the pupil­lary margin after 3-5 minutes after injection of the dye when examined with a blue filter. The conjunctival vessels fill up with the dye seconds after the retinal vessels receive the dye. The dye freely leaks out to stain i he subconjunctival tissues. However, dye decrease of concentration in the conjunctive can be noticed after 3-5 minutes. By 30-45 minutes after injection the fluorescein concentration in the aqueous is the highest and that in the subconjunctival tissues is fairly low. As such this was the optimum time for study of aqueous veins. The intermittent pressure on the globe is important for demonstrating these channels. Dark adaptation was of immense value in visualising the faint fluorescence of the aqueous veins. Aqueous veins could be visualised in 14 eyes which include all the 8 eyes studied by intracameral method. The method was simple, safe and very effective.

However, the fluorescein staining of the subconjunctival tissues and perhaps the sclera seriously reduced the contrast.

Intracameral Injection Technique

  1. The dye concentration of 0.1% was rather too low for fluorescence photography. Both 0.2% and 0.3%. provided adequate dye concentration. However, the case where 0.3% dye was injected had a mild iritis. On a suspi­cion that this concentration could be responsi­ble for iritis, 0.2% was taken as standard con­centration.
  2. Retrobulbar anaesthesia had no advan­tage. It did create some problem in photo­graphy for ocular movements were restricted. Hence considered unnecessary.
  3. Fixation of the globe : Fixation with a forceps often caused injury to the conjunctiva making it difficult to visualise aqueous veins in the area. Stabilising with a cotton swab was found adequate.
  4. Conjunctival Flap. Raising a flap pro­vides no advantage. On the other hand, traps some regurgitated dye which cannot be washed away. This procedure was abandoned.
  5. Perpendicular incision at the limbus was associated with rapid leakage of aqueous causing frequent hypotony. The dye drainage with low ocular pressure was poor. The oblique incision solved this problem.
  6. Eight blind eyes were studied by this method.


Visualisation of Aqueous Veins

Since very high concentration of the dye was achieved by intracameral injection, the aqueous veins were clearly visible. Furtermore, the absence of background tissue staining with fluorescence resulted in excellent contrast for photography. However the number of aqueous veins visualised in 8 cases studied by this method was same as studied by intraven­ous technique.

Though the dye could be detected even after 10 hours after injection the best time for study was first 3-4 hours.

Undoubtedly this was the most dramatic method for study of aqueous veins and the method of choice for 'Fluorescence photo­graphy'. However, it is a potentially risky procedure. As such should be resorted to with extreme care when photographic record is desired.

Types of Aqueous Flow in the Aqueous Veins

Interestingly the classical 'unilateral lami­nar flow' was less commonly detected than mixed flow or even 'central laminar flow'. The flow pattern often changed with variable degree of bulbar pressure. If one compares the same aqueous veins complexes following findings are noted :­

(A) The aqueous veins on the right of the frame. An aqueous vein with high dye concentration joins 2 other aqueous channels at their meeting point (fork of the 'y'). Of the latter 2 the right carries a thin lamellar flow of aqueous but the left is almost completely filled with blood. After the meeting the common channel now shows a central laminar - flow. In the left channel is seen carrying a lot of aqueous, while the right carries a mixed flow. The common trunk shows a mixed flow with left laminar pro­minence. Lastly the aqueous flow in the right tributary has improved resulting in a wide aqueous flow with a thin blood laminar flow on right.

(B) The aqueous vein on the left of the frame. The right tributary is seen carrying very high concentration of aqueous (complete filling or pure fluid). The corresponding aqueous vein is carrying a mixture of blood and aqueous. Another tributary aqueous channel joining this channel (corresponding channel is not in the picture) is showing a classical unilateral lamination of aqueous flow.

Thus the aqueous flow in aqueous channels may assume following patterns : (i) Lateral laminar flow (ii) Central laminar flow (iii) mix­ed flow (iv) Pure flow.

Fluorescence Photography of Aqueous Veins

The fluorescence photographs were obtain­ed most satisfactorily under following condi­tions and settings :­

A. 1. Slit aperture wide open

2. Excitation Filter : B.G. 12

3. Flash intensity : Step IV

4. Image magnification : x 16

5. Image aperture : f = 16

B. Robot Motor Camera :

1. Shutter speed : 1/30 sec.

2. Barrier Filter : Schott. G.G. 14, 3 mm.

3. Flash setting : X

4. Film : 400 ASA, Panchromatic black and white (ORWO)

The films were exposed at appropriate moments to capture different patterns of aqueous flow under variable digital bulbar pressure. While it was easy to obtain high quality fluorescence photographs after intra­cameral injection of fluorescein, it has not been possible to get satisfactory results after intravenous injections.


  Discussion Top


It is evident that it is not possible to detect all aqueous veins by simple slit lamp examina­tion [Table - 1].

Local instillation of fluorescein/does not offer any advantages over this method.

Number of aqueous veins seen by intraven­ous technique was significantly greater than detected by first 2 methods.

Intracameral injection of fluorescein in 8 cases did not reveal any more aqueous veins than noted by intravenous technique in the same 8 cases. However, the detection was far easier and fluorescence photography was high­ly satisfactory. Yet, it remains a potentially risky procedure.

Thus the slitlamp & local fluorescein in­stillation methods are sufficiently unsatis­factory to be discarded as not meaningful methods for study of aqueous veins.

Intravenous injection technique is con­venient, safe and highly effective in detection of aqueous veins. However in 2 eyes out of 16 eyes examined no aqueous veins could be detected. Intravenous injection of the fluores­cein should be recommended for routine demonstration of aqueous veins.

Intracameral injection technique is by far the most ideal method to demonstrate aque­ous veins and it is the only method where fluorescence photographs could be taken. Intracameral injection should be reserved for cases where fluorescence photography is desired.


  Summary Top


Methods of study of Aqueous veins are evaluated[3].

 
  References Top

1.
Ascher, K.W., 1961, Appearance of aqueous veins. The Aqueous Veins. pp. 38-52-Charles C. Thomas U.S.A.  Back to cited text no. 1
    
2.
Arkin, W. and Przodka, L. 1973. : The role of fluorography in the detection of filtering scars after antiglaucoma operations. Ophthalmologica, 166 : 436.  Back to cited text no. 2
    
3.
Benedikt, O. Die Darstellung des Kammer Wasserabflusses normaler and glaukornkranker men schlicher Augen durch Fullung der Vorderkammer mit Fluorescein. Albrecht V. Graefes. Arch. Klin. Exp. Ophihal. 109: 45, 1976.  Back to cited text no. 3
    



 
 
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