|Year : 1966 | Volume
| Issue : 1 | Page : 26-30
Hypotony in cataract surgery
DG Mody, TN Ursekar
Ophthalmic Department, King Edward Memorial Hospital, Parel, Bombay, India
|Date of Web Publication||12-Jan-2008|
D G Mody
Ophthalmic Department, King Edward Memorial Hospital, Parel, Bombay
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Mody D G, Ursekar T N. Hypotony in cataract surgery. Indian J Ophthalmol 1966;14:26-30
Advances in cataract surgery have taken place in recent years with the advent of various anaesthetics and drugs given prior to the operation. However with these newer drugs, fresh complications have also been seen to occur after surgery. The worst complication is that of vitreous escape. In order to avoid it a really soft eye is needed prior to surgery. Although retrobulbar injection of an anoesthetic (Xylocaine) along with digital compression brings about a lowering in the intraocular pressure, it was found that this effect varies significantly with age and the method was not sufficient to soften the eye in all cases. Reese does not use retrobulbar injection prior to cataract surgery in order to avoid retrobulbar haematoma and pressure over the eye. He believes that such an injection is prone to give rise to vitreous prolapse or bulging during the operation. Recently Urretts Zavalia has shown that acetazolamide has another action besides the inhibition of the enzyme carbonic anhydrase, namely alteration of the colloidal state of the vitreous by reducing its water content. This increases the viscosity of the vitreous and reduces its volume. By using acetazolamide pre-operatively, one can further reduce the intraocular pressure, rendering intraocular manoeuvers easy without any risk of vitreous escape.
He uses acetazolamide two days prior to the operation in the dosage of 250 mgm - 6 hourly and 250 mgm to 500 mgm intravenously an hour before operation. When we used this dosage schedule, number of patients complained of paraesthesias, anorexia and gastrointestinal upset. It was therefore decided to find out the lowest dose of acetazolamide that can be used in our patients without much of side effects but with the advantages of hypotony during cataract surgery.
| Method and Material|| |
Two hundred and thirty six consecutive cases of cataracts were studied for this series. One hundred and fortytwo cases were given acetazolamide in various dosages whereas the others served as controls. The cases were divided into various age groups along with control groups. The table opposite is prepared according to the following schedules.[Table - 5]
As a premeditation besides acetazolamide all the patients were given Tab Siquil 10 mgm mid Medomin 200 mgm - half an hour before the operation.
Intraocular pressure was taken on admission, before retrobulbar and after retrobulbar injection of novocain and adrenalin in all cases.
[Table - 1] shows the intraocular pressures in the various age group in control and acetazolamide series. A significant fall in intraocular pressure is seen when acetazolamide was started two days prior to the operation. If acetazolamide is given a day before the operation as shown in schedule IV one again sees a definite fall in the intraocular pressure, compared to that in the control group. This dosage schedule was found adequate as it did not cause any side effect of acetazolamide in our patients.
The control cases got the same premedication and retrobulbar injection of novocain with adrenalin but no acetazolamide.
Observations were made on the following lines during and after the operation in each case: (1) Positive pressure effect (2) Condition of the eye ball, selera and cornea (3) Iris whether it collapsed after removal of the lens or not and (4) the status of the vitreous.
| Results|| |
The results are shown in a tabulated form in [Table - 1],[Table - 2],[Table - 3].
The five cases in which vitreous disturbances occurred in spite of giving acetazolamide prior to the operation belong to the group (V & VI) where acetazolamide was given a day before the operation and a few hours before the operation respectively. In cases where diamox was given in sufficient dosage no vitreous disturbance was noted. There were no other complications seen after the cataract operation in this series. [Table - 4].
| Comments|| |
It will be evident from the study that if acetazolamide is given in sufficient quantity, the dreaded complication of vitreous escape can be avoided effectively in almost all cases and in almost any age group. The need for such a soft eye is invariably felt when one is performing operations in complicated cases and in younger age groups.
Urrets Zavalia and Byod claimed that there was no vitreous escape in a series of 100 cases in their hands where acetazolamide was given preoperatively. Although vitreous disturbance was observed in 5 of our cases, it is to be noted that in these cases the dose of acetazolamide was inadequate. Even then whatever vitreous disturbance occured consisted of escape of fluid vitreous in 3 cases and solid vitreous in two cases. The three cases where fluid vitreous came out, were patients between the ages of 55 to 65 years and the two cases of solid vitreous escape were young patients with complicated cataracts. In the latter cases, there were firm adhesions between the iris and the lens and the extraction required more manipulation of the eye ball which probably was the cause of vitreous prolapse.
In order to avoid the side effects of acetazolamide, we reduced the dose in such a way that it was cliclinically useful. [Table - 2] shows the average fall of intraocular pressure in three age groups in various dose schedules in both the diamox and the control series. It will be evident that there is a significant fall in intraocular pressure in groups III and IV in the diamox series. A minimum dose of 250 mgm 6 hourly a day prior to the operation and 500 mgm 2 hour before operation was found useful in bringing down the intraocular pressure. In higher dosage schedule, some of the patients do complain of gastrointestinal upset or anorexia, especially where aceta7olamide has been started 2 days prior to the operation in a 6 hourly dosage schedule.
With a reduced pressure, we found that the extraction of the lens was easier and quite often the iris diaphragm was seen to fall back after the lens was removed. Where the intraocular pressure became very low, the cornea was seen to become concave after the removal of cataract. The post operative course was uneventful in all the cases. Because of such hypotony, there was no incidence of a shallow chamber prior to the operation. Diamox was not given after the operation.
Clinically the hypothesis of Urretts Zavalia (that of retraction of the vitreous due to reduction of its water content) seems to have some significance. No positive pressure effect was seen nor was there any bulging of the anterior vitreous face after the removal of the lens. On the contrary the anterior vitreous face was either flat or concave.
Besides premedication and retrobulbar anesthesia, acetazolamide does play a major role in bringing down the intraocular pressure especially if one gives Diamox as denoted in Schedule No. III. This table shows that the intraocular tension does come down significantly. This has been amply proved even statistically when one takes a look into [Table - 3].
| References|| |
Boyd B. F., Highlights of Ophthalmology 1962.
Urrets Zavalia, Quoted by Boyd B. F. in Highlights of Ophthalmology 1962.
Armaly M. F. and Halasa A. TI., Effect of external compression of the eye on intraocular pressure. Pt. 1, Invest. Ophth. 2, 591, 1963.
Ibid: Pt. II Invest. Ophth. 2; 599,1963.
[Table - 1], [Table - 2], [Table - 3], [Table - 4], [Table - 5]