|Year : 1991 | Volume
| Issue : 1 | Page : 12-14
Achievement of surgically soft and safe eyes--a comparative study
RN Sud, R Loomba
Dept. of Ophthalmology Dayanand Medical College and Hospital, Ludhiana, Punjab, India
R N Sud
Dept. of Ophthalmology Dayanand Medical College and Hospital, Ludhiana, Punjab
Source of Support: None, Conflict of Interest: None
With the advent of intra ocular lens implantation at the time of cataract extraction, especially by intracapsular method, it has become very important to prevent the loss of vitreous during surgery. This can be achieved by lowering the intraocular pressure by various methods. In order to find out the best method to achieve a soft & safe eye before surgery, a study was conducted on 90 patients, undergoing intracapsular cataract extraction. The patients were divided into 9 groups of 10 each, & different methods of lowering intraocular pressure were tried and results compared. It was observed that intravenous mannitol given preoperatively and pressure with mercury column together, formed the best combination to achieve the maximum tension lowering effect.
|How to cite this article:|
Sud R N, Loomba R. Achievement of surgically soft and safe eyes--a comparative study. Indian J Ophthalmol 1991;39:12-4
| Introduction|| |
A surgically soft & safe eye is essential during cataract operation, especially when intraocular lens implantation is to be done, and this can be achieved by pre-operative reduction of intraocular pressure. If the eye is soft before surgery the vitreous phase will remain concave after lens extraction and this will prevent its loss and help in quick and successful implantation of the intraocular lens.
Intraocular pressure can be lowered by the following methods:
1. Use of medicines like carbonic anhydrase inhibitors, e.g. Diamox; or osmotic agents like oral glycerol, intravenous urea or mannitol.
2. Orbital decompression by (a) digital massage, (b) pressure with Super Pinky ball, (c) pressure with mercury column (d) Honan intraocular pressure reducer.
The present study was undertaken to find out the best method to achieve a soft & safe eye before intracapsular cataract extraction, especially for intraocular lens implantation.
| Material and methods|| |
90 patients admitted to the hospital for cataract extraction, were included in the study. A thorough general physical and ophthalmological (including slit lamp) examination was done in each case. The patients were divided into 9 groups (A to I) of 10 each. In group A (control group), intraocular pressure was recorded 3 times i.e. before retrobulbar anaesthesia, after retrobulbar anaesthesia & 3-5 minutes after digital massage. In each of the remaining 8 groups, B to I, the intraocular pressure was recorded by Schiotz tonometer and the initial reading was labelled as To, while the subsequent ones were labelled as T1, T2 & T3. Diamox 2 tablets (500 mg) were given 3 hours before surgery, to patients in groups B,C,D & E. 300 ml of 20% mannitol was given by intravenous drip in 30 minutes to patients in groups F,G,H & 1, and the patients were observed for any drip reaction or any other complication. Retrobulbar anaesthesia was given as a mixture of 1 ml of 2% xylocaine & 1 ml of 5°/ bupivacaine (Marcaine) with a fine needle. Digital pressure was applied for 3-5 minutes after keeping a sterile pad over the eye, the pressure being released for 5 seconds after every minute. Mercury column pressure was applied in patients of groups D,E,H & I, by using a paediatric sphygmomanometer cuff which was connected with the mercury column. The off was tied around the eye to be operated, after .keeping 2-3 eye pads. A pressure of 40 mm Hg was applied for 15 minutes and during this procedure, blood pressure and pulse rate were monitored. Intracapsular cataract extraction was performed by cryo, Smith Indian technique or by intracapsular forceps.
| Observations|| |
Out of 90 patients included in the study, 51 were males & 39 females. The age of ~patients varied from 45-75 years, with an average of 64 years.
[Table - 2] shows the total reduction of intraocular pressure in each group. The effect of Diamox on intraocular pressure, as observed by comparing groups A & C, was found to be statistically insignificant (P is greater than 0.05).
The effect of mannitol on intraocular pressure, as found out by comparing group A with G, was highly significant (P is less than 0.01).
To compare the tension lowering effect of digital massage and pressure with mercury column, groups B & D, C & E, F & H and G & I were compared. Mean reduction in intraocular pressure, after pressure with mercury column, was more (8.8+0.3 mm Hg) as compared to that after digital massage (5.4 ± 0.3mm Hg) and the difference was statistically significant. There was no statistically significant difference in intraocular pressure before (9.3 ± 0.6 mm Hg) and after retrobulbar anaesthesia (10.29 ± 0.5 mm Hg). In fact, in 45 patients (50%), there was a statistically significant increase in intraocular pressure (2.8 mm Hg) after retrobulbar anaesthesia.
| Discussion|| |
The importance of preventing operative loss of vitreous during intracapsular cataract extraction, has been known for a long time, but it has gained more significance these days, because of the advent of intraocular lens implantation surgery. It is generally believed that low intraocular pressure immediately before the anterior chamber is opened, reduces chances of vitreous loss.
Becker sub showed that Diamox in a dose of 500-1000 mg reduced intraocular pressure in normal and glaucomatous eyes, though the effect was much less in normal eyes. Aggarwal & Malik  reported a decrease in incidence of vitreous loss during cataract surgery, following Diamox administration. On the other hand, Gartner ; Gundzik & Mayer ; and Robbins et al  did not find Diamox to be of any benefit in patients undergoing cataract surgery. In our study too, we did not find any statistically significant fall in intraocular pressure, following Diamox administration.
Hill ; Venturi & Barca sub ; Jaffe ; and Engelstein  recommended the use of intravenous mannitol before cataract surgery. Hill  found a mean reduction of 7.2 mm Hg in intraocular pressure. In our study, the mean fall in intraocular pressure, following mannitol administration (as seen in group G) was found to be 5.6 mm Hg, more as compared to the control group (group A) and this difference was highly significant statistically (P is less than 0.01). Comparing the effect of mannitol with Diamox, on intraocular pressure, we found the effect of mannitol to be highly significant and that of Diamox insignificant.
Kirsch & Steinman , in a study on 100 cases, observed an average fall of 9.6 mm Hg in intraocular pressure following digital massage. Kirsch  in a further study, found a fall of 8.0 mm Hg after 2 1/2 minutes of massage. The value for the same was 7.2 mm Hg in studies conducted by Metz . In our study, the value was 5.4 mm Hg., less than that of other workers.
Quist et a1  used Honan's device after retrobulbar injection, at a pressure of 30 mm Hg for 5 minutes and noted an average fall of 6.5 mm Hg in intraocular pressure. Martin et al , following application of Honan's reducer for 40 minutes after retrobulbar anaesthesia, noted an average fall of 6.7 mm Hg in intraocular pressure. In the present study, the fall in intraocular pressure obtained with mercury column was 8.8 mrn Hg., slight more than that obtained by Quist et a1  &Martinet al .
On comparison of groups B & D, C & E, F & H and G & I, in our study, it was observed that a fall in intraocular pressure, after pressure with mercury column (8.8 ± 0.3 mm Hg) was significantly higher than that after digital massage (5.4 ± 0.3 mm Hg). There are controversial reports on the role of retrobulbar anaesthesia in lowering~ intraocular pressure. Gifford ; and Kirsch & Steinman  noted a marked fall in intraocular pressure after retrobulbar anaesthesia, whereas Metz ; Herschenfield & Breslin ; and Quist et a1  failed to record any observable effect in lowering intraocular pressure. In contrast, Kim et a1  and Jay et a1  noted an increase in intraocular pressure in most eyes after retrobulbar anaesthesia.
In the end, it may be concluded that intravenous mannitol produces a marked fall in intraocular pressure; and digital massage & pressure with mercury column both produce a significant fall in intraocular pressure but the effect was more marked after pressure with mercury column, especially after retrobulbar anaesthesia. It is further concluded that the ideal combination to reduce intraocular pressure before cataract surgery would be intravenous mannitol and pressure with mercury column.
| References|| |
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[Table - 1], [Table - 2]