ACTA OPHTHALMOLOGICA VOL. 4 0 1962

From the University Eys Debt., Rikshospitalet, bslo (Head: P r o f . Dr.med. T . L. Thomassen)

THE EFFECT OF STREPTOKINASE IRRIGATION ON EXPERIMENTALLY CLOTTED BLOOD IN THE ANTERIOR

CHAMBER OF HUMAN EYES")

BY

Bjorn Berger

Plasminogen (profibrinolysin) is a proenzyme found in the plasma globulin fraction. It can be activated to form plasmin (fibrinolysin), a proteolytic enzyme which dissolves fibrin, by various activators such as streptokinase, a bacterial product, and urokinase, extracted from human urine. Streptokinase cannot act directly on plasminogen, but interacts first with a proactivator, the resulting complex forming the actual activator. Human plasma contains con- siderable quantities of proactivator, whereas animal plasma contains much smaller amounts. Experimental results in animals and man will not, therefore, be exactly comparable.

Alkjaersig ( 1 ) states that a fibrin clot may be dissolved in two ways: external action of plasmin, breaking down the clot from the surface, or activation ot

plasminogen adsorbed to fibrin by means of an activator. The latter appears to be the more effective in dissolving preformed fibrin ( 1 ) . This observation is of importance in choosing therapeutic fibrinolytic agents.

In theory, fibrinolytic therapy may be carried out by means of an activator, for example streptokinase or urokinase, by means of plasmin, or by a mixture of plasmin and activator.

Several commercial streptokinase preparations are available on the market today. Kabikinas Kabi is a relatively pure streptokinase preparation, ad- ministered intravenously to large series of patients with no serious toxic side effects (13). Other products include mixtures of streptokinase and plasmin (14) (Actase Ortho and Thrombolysin M. S. D.). Sawyer (14) reported that the effect of these products was mainly due to their streptokinase content, as

") Received 12th May 1962.

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plasmin quantities were relatively negligible. Reports are available of probable thrombolysis following intravenous use of several of the preparations men- tioned above (6, 7). Local application, i. e. in the anterior chamber of the eye, is also possible.

Varidase Lederle is an oral streptokinase preparation, which has also been used in treatment of ocular thrombosis and haemorrhage (9, 10). Berger and Blix (2) found that the effectiveness of this preparation is doubtful.

Use of fibrinolytic therapy in ophthalmology is still at the experimental stage. Jukofsky, in 1951 (11), injected large amounts of streptokinase into an eye

with post-traumatic hyphema, the anterior chamber of which was filled with apparently coagulated blood, signs of rise in ocular pressure being present. The blood had practically disappeared from the anterior chamber within an hour. No serious complications could be detected in the anterior parts of the eye as the result of streptokinase injection. Friedman, in 1952 (8), injected streptokinase into the anterior chamber of human eyes with resulting disastrous side effects. Braley, in 1955 (4), had the same experience. Fletcher, 1959 (7), used intravenous streptokinase four days running, in treating a 71 year old man with an intraocular infection following cataract extraction, which resulted in a dense fitxinous exudate filling the anterior chamber. Slit lamp observations showed gradual resorption of the fibrin with complete disappearance at the completion of treatment. Scheie, in 1961 (15), used Thrombolysin irrigation in two eyes with total hyphema, the blood being washed out 15 and 30 minutes later, respectively. No serious side effects, due to Thrombolysin, were observed.

Thrombosis of the central retinal vein and central retinal artery, are amongst other conditions treated experimentally with fibrinolytic agents (5 ) .

The purpose of the present investigation is to determine whether strepto- kinase irrigation can dissolve coagulated blood in the anterior chamber of human eyes, and whether any local side effects of irrigation can occur in the anterior parts of the eye.

M A T E R I A L S A N D M E T H O D S

Streptokinate. The streptokinase preparation used was Kabikinas Kabi, kindly supplied by A. B. Kabi, Stockholm, in vials containing 250,000 units. It was diluted to 625 unitdml with physiological saline, stored frozen and thawed just prior to use. This concentraticm was chosen because it excerted optimal effect in a plasma clot system (3).

Thrombin (Topostasin, Roche) was dissolved in physiological saline to 30 unitdml.

Eyes. Eight human eyes were used, six with absolute glaucoma, one with a posteriorly situated int rabulbar malignant melanoma and one painful blind eye.

Collection of blood. Nine parts of blood were collected in one part of 3. i3 g per cent sodium citrate dihydrate solution and shortly afterwards injected into the anterior

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chamber of the same patients eye. For platelet poor plasma, blood was collected as mentioned above and immediately centrifuged at 4 O C. for 30 min. at 2,500 r. p. m. (1,400 G). The plasma was at once pipetted off and shortly afterwards injected into the interior chamber.

Anesthesia. 2 O/o Xylocain-Exadrin w Astrau was injected retrobulbarly a short time before start of the test. 1 O/o Tetracain was applied to the cornea during the test.

Chamber puncture was performed at the limbus, in the temporal part of the bulbus, using a no 23 hypodermic needle.

INVESTIGATIONS AND RESULTS

I . Production 5f blood clots in the anterior chamber. Almost the entire aqueous was removed from the anterior chamber and approximately 0.15 ml of the patients citrated blood was injected (platelet poor citrated plasma was used in one eye), followed by injection of 0.05 to 0.1 ml thrombin.

2. Irrigation was usually started 20 minutes after formation of the clot. In one case the time interval was 20 hours and in another 48 hours. Continuous irrigation was performed using a 2 ml. syringe, alternate careful aspiration and injection being carried out. a) Physiological saline irrigation was used initially in all cases, to ascertain that the anterior chamber contained clotted blood only. 2 of the eyes were irrigated with saline for 20 and 30 minutes respectively, without signs of clot lysis. Irrigation was impossible in the eye containing a plasma clot. The explanation for this can only be that the anteror chamber was filled with fibrin. 6 ) Streptokinase irrigation was carried out immediately after the saline irri- gation in all 8 eyes, using an average of 6-8 ml. A finaI rinse with physiological saline was given.

3. Results. Clots in all the eyes showed signs of lysis within 1 minute of commencing streptokinase irrigation. Time for total lysis varied from 20 to 55 minutes (average 40 minutes). In most cases a minute portion of the clot did not dissolve, remaining as a thin layer covering the pupil or approximately 1/4 of the iris. 2 eyes were observed further and in these, clot remnants were found to dissolve within a few hours. The 2 days old clot dissolved in 35 minutes and the 20 hour clot in 45 minutes.

4. Complications. 6 eyes were enucleated immediately after conclusion of irrigation. Observation period for 'one eye with absolute glaucoma and the eye with intrabulbar tumor, was 6 days.

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A severe chemosis and iridocyclitis developed in the glaucoma eye, with increasing fibrin deposits in the anterior chamber, more than half the chamber being filled by the end of the 6th day. Tension remained throughout at the high initial levcl.

Reaction was moderate in the tumor eye. A mild iridocyclitis developed and the cornea showed a few descemetfolds and a slight roughening of the surface, though some fibrin threads were present in the anterior chamber. No changes other than iridocyclitis were observed. The lens was not affected, and a transient impaired vision was over by the 6th day, visual acuity being as at the $tart of the test, i. e. fingercounting at a distance of 1 m. Tension remained normal throughout. Topical hydrocortisone was used from the 3rd day.

Special \ignificance cannot be attached to the severe reaction observed, as we know that eyes with absolute glaucoma are usually very sensitive. The relatively mild local reaction observed in the tumor eye, however, is of much greater interest for practical purposes; though one cannot know what the long term reaction in this eye would have been.

DISCUSSION

Prognosis in the case of traumatic hyphema and secondary hamorrhage in an eye may bz grave (12, 16). There is reason to assume that prognosis can be improved in some of these cases with clotted blood in the anterior chamber if the clot can be dissolved at an early stage, using a reagent which does not cause severe local side effects.

The tests carried out in this study have demonstrated that coagulated blood (up to 2 days old) and fibrin deposits in the anterior chamber of the human eye, can bc dissolved almost completely, using streptokinase irrigation at a strength of 625 unitsiml.

Side effects of streptokinase irrigation in the 2 eyes in this series with a 6 day obsei vation period, are described and discussed under complications.

The problem of clot lysis, in experimental hyphema, as produced here, does not differ substantially from that encountered in the case of natural hyphema. The anterior chamber is not filled completely with blood, but this is not significant, as the capacity of streptokinase to dissolve a clot is independant of the size of the clot.

Local side effects as a result of streptokinase irrigation in the anterior chamber are possibly due, in part to a toxic effect, and partly to an immuno- logical reaction of antigen-antibody type. Irrigation itself, and the pressure variations in the anterior chamber, will also play a part. W e are still uncertain as to whether irrigation, or one or more injections of streptokinase, is the best

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method to dissolve coagulated blood in the anterior chamber; or whether streptokinase is preferable to streptokinase-plasmin preparations. Other sub- stances such as urokinase or very high concentrations of plasmin, may perhaps be preferable in dissolving blood clots in the anterior chamber of the human eye.

S U M M A R Y

Coagulation of blood by means of thrombin was obtained in the anterior chamber of 8 eyes prior to enucleation. The resulting clots were almost com- pletely dissolved within 20 to 55 minutes by streptokinase irrigation.

2 of the eyes were observed for 6 days. Severe iridocyclitis developed in one eye with absolute glaucoma. The other eye, with a posterior intrabulbar tumor and normal anterior parts, showed mild signs of iridocyclitis which cleared considerably during the observation period.

A C K N O W L E D G M E N T

My sincere thanks to Dr. S. Blix from the Medical Department A for his kind cooperation and assistance.

REFERENCES

1 . Alkjuersig, N . , Fletcher. A . P . & Sherry, S . : The mechanism of clot dissolution

2. Berger, B. & Blix, S.: An evaluation of the effectiveness of streptokinase in buccal

3 . Blix, S.: Antibodies after streptokinase treatment, and their importance for re-

4. Brnley, A . E., in discussion of paper by O'Rourke, J. F.: An evaluation of intra-

5 . Cl i f f ton , E. E.: Early experience with Fibrinolysin. Angiology 1959: 10: 244. 6. C l i f f t o n , E. E.: Fibrinolysin as an agent for treatment of thromboembolic accidents.

J. A. M. A. 1961: 175: 302. 7 . Fletcher, A . P . , Sherry, S . , Alkjnersig, N . , Smyrniotis, F. E . & l i c k , S . : The main-

tenance of a sustained thrombolytic state in man. 11. Clinical observations on patients with myocardial infarctions and other thromboembolic disorders. J. Clin. Invest. 1959: 38: 1 1 1 1 .

8 . Friedman, M . W.: Streptokinase in ophthalmology. Am. J. Ophth. 1952: 35: 1184. 9. Hurwitz , P.: Buccal Varidase in Ophthalmology. Am. J. Ophth. 1959: 48: 823.

10. Jonkers, G. H.: Die Anwendung von Varidase in der Augenheilkunde. Klin. Mbl.

11. l u k o f s k y , S . L.: A new technique in the treatment of hyphema. Am. J. Ophth.

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13. Olow, B. & Nilsson, I . M . : Streptokinase induced fibrinolysis in man. Proceedings of the eighth congress of the European Society of Haematology. Vienna 1961. 11. 444.

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16. Thygeson, P . & Beard, C.: Observations of traumatic hyphema. Am. J. Ophth. 1952: 35: 977.