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   Table of Contents      
ARTICLE
Year : 1961  |  Volume : 9  |  Issue : 2  |  Page : 25-29

Use of alpha-chymotrypsin in cataract surgery with special reference to the duration of application


Department of Ophthalmology, School of Medicine, Tokushima University, Japan

Date of Web Publication31-Mar-2008

Correspondence Address:
Yukihiko Mitsui
Department of Ophthalmology, School of Medicine, Tokushima University
Japan
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Source of Support: None, Conflict of Interest: None


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How to cite this article:
Mitsui Y, Takagi Y. Use of alpha-chymotrypsin in cataract surgery with special reference to the duration of application. Indian J Ophthalmol 1961;9:25-9

How to cite this URL:
Mitsui Y, Takagi Y. Use of alpha-chymotrypsin in cataract surgery with special reference to the duration of application. Indian J Ophthalmol [serial online] 1961 [cited 2020 Aug 5];9:25-9. Available from: http://www.ijo.in/text.asp?1961/9/2/25/39679

Since a-chymotrypsin* was introduc­ed by J. Barraquer in (1958), there have appeared a number of reports [2],[3],[4],[5],[6] discussing about the merits and demerits of the employment of this new agent in cataract surgery. To date three problems have been dis­cussed concerning the use of this new agent. They are as follows

1) Does the agent actually faci­litate the lens-extraction ?

2) Does the agent show any un­favourable side-effect on the surgery ?

3) What are the best concentration and duration of application ?

During the past one year period we have evaluated the use of this new enzyme in lens-extraction. The result of the surgery with this new agent was compared with that of the surgery without this agent (forceps and suction method) as done by the present authors during the past ten years. At the same time the most suitable method to employ in combination with this enzyme was investigated among for­ceps, suction and pressure techniques. In the present communication a sum­marized conclusion with technical dis­cussions will be given.

Selection of Extraction Procedure.

The following three procedures were compared to find the most suitable method to employ in combination with a-chymotrypsin,

a. Capsule forceps (Castroviejo­type )

b. Suction apparatus (Bell-type)

c. Pressure technique

The first two procedures using either of the forceps or the suction apparatus showed some disadvantages. By a-chymotrypsin the suspensory liga­ment became ready to cut and the removal of the lens was facilitated very much. However, when such in­struments as forceps and suction ap­paratus were introduced into the anterior chamber, they naturally gave mechanical injuries to the posterior surface of the cornea and caused an opacity of this tissue along with fold­-formation of Descemet's membrane. Such an injury and corneal opacity occurs even without a-chymotrypsin but the injury was apt to be great when a-chymotrypsin was used. This may be due to a ferrnentative action of a-chymotrypsin which affects the posterior surface of the cornea chemi­cally and thus accelerates the mechanical injuries by the instruments. The opacity was transitional and was roughly cleared in a course of some one week. But a trace of injury as seen by slit lamp microscopy persisted longer and frequenter with a-chymo­trypsin than without a-chymotrypsin.

The pressure method as first in­troduced by Smith (1911) long before the introduction of a-chymotrypsin. This method has been ignored for a long time as the forceps and suction method were far better and safer for intracapsular extraction. After the in­troduction of a-chymotrypsin, how­ever, the pressure method warranted attention. The following advantages were encountered when the pressure method was employed in combination with a-chymotrypsin.

1) The extraction of the lens was as easy as the extraction of the lens nucleus by extracapsular technique.

2) The extraction did not fail so far in patients over 30 years of age. Only in a few cases between 20 and 30 years of age (they were extractions for the removal of the lens due to high myopia), the pressure method was substituted by forceps.

3) The injury of the posterior surface of the cornea was negligible. The cornea was used to be perfectly clear on the second day of surgery.

4) Eventual rupture of lens cap­sule did not occur during delivery.

Determination o f Duration of Alpha-chymotrypsin Application. In case of employing capsule forceps and suction apparatus in combination with a­chymotrypsin, the duration of enzyme application is not an essential problem. These methods can be employed by themselves for intracapsular extraction and a-chymotrypsin, though it assists extraction very much, is rather op­tional at least in patients over 40 years of age. When a-chymotrypsin is used with these techniques, the only care to be taken is to avoid an overaction.

The pressure method, on the con­trary, can be employed as a safety measure for intracapsular extraction only in combination with a-chymo­trypsin_ In this case an excess and deficiency of the enzyme action should be avoided as far as possible, parti­cularly the deficiency. Because a delivery by pressure may suffer badly from a deficiency of enzyme action.

The best duration of a-chymotrypsin application differs from one case to another considerably. It must be determined in individual cases. After a series of trials, the following pro­cedure was found to be suitable for the checking of the expected end point of enzyme application.

After irrigation of the posterior chamber with the enzyme solution, two spatulas (a combination of one Daviel's spoon and one Hess' half­loop can be used as illustrated in [Figure - 3] are put on the sclera 12 and 6 o'clock position. A see-saw pressure is given to the sclera in the perpendi­cular direction to the eye-ball just like the motion to extract lens nucleus by an extracapsular technique.

The iris has been given a peripheral iridectomy at 12 o'clock prior to the enzyme application. The movement of the lens by the see-saw pressure can be observed from the iridecto­mized hole of the iris. The observation is facilitated if an assistant pulls the corneal flap frontwards by forceps. [Figure - 3]. Unless the lens-equator elevates into the iris hole the effect of the enzyme is insufficient. When the lens-equator elevates into the iris hole, it indicates the completion of the enzyme effect sufficient for intra­capsular delivery by a pressure method. Without any delay the pos­terior chamber is irrigated with saline. A considerable delay of saline irriga­tion may cause an overaction of the enzyme.

This checking procedure is also useful even if forceps or suction ap­paratus is used for delivery. The time until the lens-equator elevates up to the iris hole differs greatly according to cases. In our experience it varies from one half minute to four minutes, when the enzyme solution is used at the concentration of 0.2 in and is warmed to 37°C before use.

Irrigation of the posterior chamber with the enzyme and saline requires some precautions. When a pressure method is employed for delivery, it is wise to deliver the lens from the top. A delivery with tumbling is useless; it may even cause an eventual com­plication during delivery.

For obtaining a smooth delivery without tumbling, the following pro­cedure of the enzyme application is recommended.

a. The irrigation with enzyme solution should be done through the iridectomized hole of the iris [Figure - 1],[Figure - 2]. The posterior chamber at the upper portion is thus irrigated first. Slightly later, the bilateral and lastly the lower parts of the chamber should be irrigated.

b. The irrigation with the saline solution after checking the end­point of enzyme application is better to be done through the pupil and not through the iri­dectomized hole [Figure - 4]. The syringe needle should be insert­ed into the lower part of the posterior chamber and this part should be irrigated first. Then the bilateral sides are irrigated. It is not necessary to irrigate the upper part specially. The upper part can readily be irri­gated by the backward flow from the lower parts.

The combination of these two pro­cedures allows the enzyme to affect the suspensory ligament more inten­sively at the upper parts, at 12 o'clock position in particular, than the lower. As a natural result, a delivery without tumbling takes place by an eye-ball compression with two spatulas. [Figure - 5],[Figure - 6].

Side-Effects of Alpha-chymotrypsin.

When the pressure method is employ­ed in combination with a-chymotry­psin with the checking-method describ­ed above, the side-effect is not obvious. The incidence of vitreous loss is con­siderably lower than the "forceps or suction method without a-chymotry­psin". The vitreous hernia into the anterior chamber was carefully examin­ed by slit-lamp after surgery. The degree of the hernia - was so far less pronounced than the forceps or suction method without a-chymotrypsin.

Occasionally, a slight irritation for which a-chymotrypsin might be .res­ponsible was observed during several days after surgery. Thus we tried prednisolone application immediately after surgery. Two tenth of ml of 2.5% prednisolone suspension was injected subconjunctivally at 6 o'clock position immediately after surgery. Since this procedure was employed, incidence of irritation reduced. On the average, post-operative irritation became less pronounced than simple forceps or suction method.

Side-effect of prednisolone applica­tion has not yet been observed. Anti­cipated side-effects may be on the one hand a delay of wound-healing, as a result of which a delay in the anterior chamber formation or a prolapse of the iris may take place. On the other hand an infection may be accelerated by prednisolone. So far, however, the prednisolone did not show any such tendencies.


  Detailed Procedure Top


After an akinesis, the anaesthesia is accomplished by a retro-bulbar injec­tion of 2 ml of 2% novocaine solution added with hyaluronidase and epine­phrine. Two fixation sutures are placed to the upper and lower rectus muscle.

The conjunctival flap is made at the upper part. The flap is triangular but at the base of the flap it is cut in a direction perpendicular to the limbus.

A sclero-corneal pre-incision is made by a knife. The pre-incision should reach two-thirds of the thickness of the coat at the limbus. The incision is then done by a keratome. The in­cision usually causes a retrogression of the diaphragm due to a fall of vitreous pressure by retro-bulbar an,Tsthesia. After the incision is made, therefore, the assistant pulls the con­junctival flap frontwards by forceps and the operator, holding de Wecker scissors in his right hand, pushes the sclera at 12 o'clock position back­wards. It causes a prolapse of the iris root. Then the operator, holding an iris forceps in his left hand, grasps the iris root by the forceps and makes a small peripheral iridectomy.

After placing a sclero-corneal suture at 12 o'clock position, the corneal incision is extended to both sides by scleral scissors. The corneal incision must reach up to 55% of the circum­ference.

The solution of a-chymotrypsin* is then introduced into the posterior chamber through the iridectomized hole of the iris in a manner as already described [Figure - 1],[Figure - 2].

The end-point of the enzyme appli­cation is determined by a procedure already mentioned and as illustrated in [Figure - 3]. Then the enzyme solution is washed away by irrigation with saline [Figure - 4]. The lens is then easily removed by a simple pressure method as shown in [Figure - 5],[Figure - 6].

After the first ligation of the sclero­corneal suture a reposition of the iris and any other tissues such as the sus­pensory ligaments is done by a spatula [Figure - 7]. Before giving the final liga­tion of the suture, subconjunctival tissues which have been enfolded with the suture are released. Three con­junctival sutures are added as shown in [Figure - 8].


  Summary of Conclusions Top


A pressure technique which had been widely used in classical extra­capsular surgery of the lens is worthy to employ in intracapsular removal of the lens when a-chymotrypsin is used. This technique is superior to forceps or suction techniques for combining with a-chymotrypsin, for it causes less damage of the posterior corneal sur­face. It also reduces the incidence of capsule rupture and vitreous loss dur­ing delivery. The vitreous hernia is less pronounced than by simple for­ceps or suction-method without a- chy­motrypsin.

The important point of this proce­dure is the determination of the end­point of enzyme application. The checking-procedure is described in detail in the present communication.[7]

 
  References Top

1.
Barraquer, J.: (1958), Klin. Mbl. Augenhk., 133: bog-615.  Back to cited text no. 1
    
2.
Remky, H.: (1958), Klin., Mbl. Augenhk., 133: 616-619.  Back to cited text no. 2
    
3.
Walser, E.: (1958), Klin. MIbl. Augenhk., 133: 619-624.  Back to cited text no. 3
    
4.
Cogan, T. E. H., Symons, H. M. and Gibbs, D.C.: (1959) , Brit. J. Ophth., 43: 193-199.  Back to cited text no. 4
    
5.
Ainslie, D.: (1959), Brit. J. Ophth., 43: 200-201.  Back to cited text no. 5
    
6.
Zorab E. C.: (1059), Brit. J. Ophth., 13: 202-203.  Back to cited text no. 6
    
7.
Smith, H.: Cited from Hirschberg, J.: Geschichte der Augenheilkunde, Graefe-Saemisch Handbuch der Augenheilkunde, 14 : 512, 1911.  Back to cited text no. 7
    


    Figures

  [Figure - 1], [Figure - 2], [Figure - 3], [Figure - 4], [Figure - 5], [Figure - 6], [Figure - 7], [Figure - 8]



 

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