|Year : 1976 | Volume
| Issue : 2 | Page : 32-36
Raised intraocular tension following the use of alpha-chymotrypsin in cataract surgery
L.T.M.G. Hospital and L.T.M.M. College, Sion, Mumbai, India
M D Oomrigar
L.T.M.G. Hospital and L.T.M.M. College, Sion, Mumbai
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Oomrigar M D. Raised intraocular tension following the use of alpha-chymotrypsin in cataract surgery. Indian J Ophthalmol 1976;24:32-6
|How to cite this URL:|
Oomrigar M D. Raised intraocular tension following the use of alpha-chymotrypsin in cataract surgery. Indian J Ophthalmol [serial online] 1976 [cited 2021 Apr 19];24:32-6. Available from: https://www.ijo.in/text.asp?1976/24/2/32/31533
The use of alpha-chymotrypsin in cataract surgery is a significant milestone in the clinical uses of enzymes. Although it was first used by Jenkins for clearing vitreous opacities and by Barraquer for clearing vitreous haemorrhage, since both of them discovered that the lens got dislocated in its use, they settled down to use it for weakening the zonular ligaments of the lens in intracapsular surgery. However, its indiscriminate use in intracapsular extraction of the lens began to show the limitations of its use. Its use now is being restricted in intracapsular surgery in the not so old; preferably those between 40 and 55 years of age. One of the side effects of its use was increased intraocular tension, and the object of this present study is confined to the possible role of the enzyme in causing increased intraocular tension.
| Transient Glaucoma|| |
Use of alpha-chymotrypsin predisposes the eye to develop transient glaucoma during the post-operative period, which from experimental evidence on owl monkeys appears to be due to the blocking of the trabecular meshwork by lysed zonular fragments. The tissue debris flows forward from the posterior chamber and becomes trapped in the trabecular meshwork.
Glaucoma ensues and lasts till the debris is absorbed. Pilocarpine benefits the glaucoma because it opens the trabecular spaces. Corticosteroids are not beneficial because the mechanism is non-inflammatory. Enzyme glaucoma is accompanied by a decrease in facility of outflow. Deep anterior chamber and open angle differentiate enzyme glaucoma from pupil-block glaucoma.
Enzyme glaucoma is dose related, in that its frequency and severity increase with larger quantity of the enzyme solution used. Even a dose as small as 0.25 ml. of the solution may cause enzyme glaucoma. For that reason the smallest quantity of enzyme should be used for successful zonulysis.
Another cause of enzyme glaucoma is that it may be due to oedema of the angle near the incision where the enzyme may exaggerate the oedema of the incision.
The peculiarity of such glaucoma is that it may be asymptomatic. However, with a high rise in intraocular tension, pain and epithelial oedema may arise. The anterior chamber is normally deep, and the chamber angle is gonioscopically open.
The peak pressure remains high for two to five days after the operation, which may be as high as 45 to 60 mm. of Hg. The average duration is about a week. The condition appears to be a self limited and the glaucoma usually disappears after a period of three weeks. No correlation exists between preoperative intraocular pressure and susceptibility to enzyme glaucoma.
The clinical importance of enzyme induced glaucoma relates to differential diagnosis and wound problems. It must be differentiated from the post-operative pupil block and angle closure glaucoma that require immediate care. It is responsible for the higher incidence of wound closure problems clinically well recognised to follow enzymatic zonulysis. Wound disruption is due to pressure and not to an effect of the enzyme on wound edges. Hence, multiple sutures help to prevent the more frequent wound problems that follow the use of alpha-chymotrypsin.
| Material, Methods and Observations|| |
This is a short term study of 50 normal cases (Group 1) of cataract extraction where the enzyme was not used; and of 50 cases (Group II) of cataract extraction where the enzyme alpha-chymotrypsin was used. An intensive post-operative study of these cases was carried out and the cases were followed up for a period of three months. In all the cases the intraocular tension was measured by means of a Schiotz tonometer daily from the third to eighth day and on alternate days from the eighth to 22nd day. Only those cases have been included in the study who came for a regular post-operative follow-up.
In all the cases, routine clinical examination was done pre-operatively. This included vision, projection, reaction of the pupil, tension, patency of sac and fundus examination before surgery. The patients having high pre-operative tension or any other ocular complications like corneal dystrophy etc. were not considered. Usual systemic investigations like blood pressure, blood sugar, septic foci and any cause of strain, etc. were carried out.
In Group I all the fifty cases were randomly selected (all the cases were over 50 years of age).
In Group II, the study of 50 cases were between the ages of 30 and 50 years. Most of the cases selected were of a younger age group who were unable to carry on with their occupation due to poor vision. The preoperative vision ranged from F. C. 1/2 metre to 6/24.
In all cases the standard technique for cataract extraction was adopted using a sclerocorneal incision without a conjunctival flap. Button-hole iridectomy was done in all cases. In the group II cases, injection of 314 to 1 c.c. of 1:5000 freshly prepared Quimotrase solution was injected under the iris. The Quimotrase solution was prepared by dissolving the powder in 5 ml. of distilled water. The solution was allowed to act for 3 minutes or till the lens appeared_ to bulge forwards, whichever was earlier. The enzyme solution was washed away by irrigation with normal saline.
Cataract extraction either intracapsular or extracapsular type was done. In the Group II cases, out of 50 cases with the use of the enzyme, in 8 cases the capsule broke, and in the remaining 42 cases the lens was removed intracapsularly.
Three interrupted corneoscleral sutures were applied in all the cases. Air was injected in the anterior chamber in all the cases.
Post-operatively from the third to the eighth day, using the utmost care, the intraocular tension was taken daily by the Schiotz tonometer. In the absence of any complications, the case was discharged after 8 days.
Atropine and chloramphenicol with hydrocortisone were prescribed post-operatively for a period of one month. The patients attended the eye operation theatre regularly on alternate days till the 22nd post-operative day. Each time the tension was noted by Schiotz tonometer. After this, a post-operative follow up was maintained once a week till one and a half months when the glasses were prescribed.
| Results|| |
In Group I, the post-operative tension taken till the 22nd day [Table - 1], of all the 50 cases was normal.
Out of the 50 cases of cataract extraction in which the enzyme alpha-chymotrypsin was used, in six cases (12%), the post-operative tension taken on the third post-operative day was found to be high. The range of tension varied from 29.4 mm of Hg. to 50.6 mm of Hg. In five cases out of six, the tension became normal on the fourth day. The dose of diamox was increased from 1 bd to 1 tds in all the cases and then gradually reduced to 1 /2 bd on the 8th post-operative day when the patients were discharged. In one case, the tension remained persistently high in spite of increasing the dose of diamox to 1 Q.I.D. The tension gradually came down and was normal from the eighth day onwards. The dose of diamox was then reduced to 1/2 tablet twice a day from the eighth post-operative day. In all the six cases the cornea appeared to be hazy. There were however no other complications in these six cases. In all the six cases, the lens was removed intracapsularly. [Table - 2]
The accompanying graph shows the comparison of tension in 50 cases of cataract extraction without the use of zonulysin as compared to the increased tension in 6 cases after the use of zonulysin, where the postoperative tension increased. (Graph I)
In Group II, the lens removal became extracapsular in eight cases due to rupture of the capsule, but there was no rise in tension recorded in any of these cases. This excluded the factor of capsular remnants causing increased tension.
An interesting feature was that in one case, both the eyes were operated using alpha-chymotrypsin and the tension was found to be high in both eyes.
| Discussion|| |
The invention of alpha-chymotrypsin for its zonulytic property has contributed significantly to the smooth intracapsular extraction.
Chee and Hamasaki made a study to determine the pathogenesis of enzyme glaucoma on owl monkeys. They came to the conclusion that the glaucoma results from the blocking of the trabecular meshwork by lysed zonular fibres.
A similar study by Schiotz tonometry was performed by Kirsch in the first post-operative week on 343 eyes after uncomplicated intracapsular extraction with the use of alpha-chymotrypsin. He found a transient, occasionally severe, glaucoma occurred in 72.5% of the eyes in which the enzyme was used. He found that despite the high tension in many cases, the glaucoma always resolved spontaneously. The cases are usually asymptomatic and unless one specifically looks for the corneal oedema and measures the tension, the glaucoma could be easily overlooked. Kirsch used filtered solution of chymotrypsin in 20 cases and found that 75% developed typical post-operative glaucoma. This excluded the cause that glaucoma could be due to suspended particulate matter.
The chief clinical importance is the recognition of the syndrome and the exclusion by differential diagnosis of the other causes of acute aphakic glaucoma which in contradistinction to the enzyme glaucoma, usually require immediate therapeutic intervention. Since elevated intraocular pressure can interfere with wound healing, it is possible that the enzyme glaucoma may be the initiating factor leading to many of the post-operative complications like flat anterior chamber, iris prolapse and wound disruption.
The finding that it does cause an increased intraocular pressure which is transient in 12% of the cases brings us to the conclusion that diamox should be used routinely in all cases post-operatively where alpha chymotrypsin has been used. This will keep the transient rise of intraocular pressure under control if it occurs.
No significant complications were observed after the use of alpha chymotrypsin, like increased incidence of striate keratitis, or wound rupture of iridocyclitis.
| Summary|| |
It was found that out of the 50 cases of cataract extraction where alpha- chymotrypsin was used, 6 cases developed transient increased intraocular tension. In the 50 cases of cataract extraction without the use of alpha-chymotrypsin, there was no increase intraocular tension.
The increased intraocular tension following the use of alpha-chymotrypsin is a transient glaucoma which usually subsides within three weeks after cataract extraction.
Thus diamox should be used routinely in all cases post-operatively, where alpha-chymotrypsin has been used for cataract extraction.
| References|| |
Barraquer, J., 1961, Arch. Ophthal., 66, 6.
Chee and Hamasaki, 1971, Arch. Ophthal., 85, 103.
Kirsch, R. E., 1964, Arch. Ophthal., 72,612.
[Figure - 1]
[Table - 1], [Table - 2]