Year : 1991 | Volume
: 39 | Issue : 2 | Page : 48--49
One point low volume peribulbar anaesthesia versus retrobulbar anaesthesia. A prospective clinical trial
NS Athanikar, VB Agrawal
H.B.M.G. Hospital, Borivli(W), Mumbai, India
N S Athanikar
H.B.M.G. Hospital, Borivli(W), Mumbai
A prospective trial was conducted on 142 patients who underwent cataract surgery, to compare the efficacy of a single point, low volume peribulbar with that of retrobulbar anaesthesia. It was found that peribulbar anaesthesia is as efficacious as retrobulbar anaesthesia without the associated complications. It also avoids the facial block used by most ophthalmologists to supplement a retrobulbar block, thus markedly reducing the post-operative patient discomfort as well as the total volume of anaesthetic used.
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Athanikar N S, Agrawal V B. One point low volume peribulbar anaesthesia versus retrobulbar anaesthesia. A prospective clinical trial.Indian J Ophthalmol 1991;39:48-49
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Athanikar N S, Agrawal V B. One point low volume peribulbar anaesthesia versus retrobulbar anaesthesia. A prospective clinical trial. Indian J Ophthalmol [serial online] 1991 [cited 2022 Jun 30 ];39:48-49
Available from: https://www.ijo.in/text.asp?1991/39/2/48/24472
Various studies have been documented to emphasise the salientfeatures of retrobulbar anaesthesia and some for peribulbar anaesthesia in ophthalmology. However, little data is available comparing the two. The present study was designed as a single blind prospective trial to compare the two modes of anaesthesia for cataract surgery.
In the past, most methods of peribulbar anaesthesia were multipoint and thus cumbersome . We have used the one point, low volume approach of Weiss et al (1989). Thus in addition to proving the efficacy of peribulbar anaesthesia in comparison with retrobulbar anaesthesia, this study also proves the utility of the single point, low volume method. This method of anaesthesia is advantageous in that it eliminates all the various complications of retrobulbar anaesthesia (eg. retrobulbar haemorrhage, central artery occlusion, ocular perforation, subarachnoid injection, brain stem anaesthesia, cardiopulmonary arrest) and the postoperative pain and edema of a facial block ,,,,,.
MATERIAL & METHODS
142 patients who underwent cataract surgery were randomly divided into 2 groups with the aid of a randomisation chart.
Group A: Retrobulbar anaesthesia. Group B: Peribulbar anaesthesia.
The administration and evaluation were done by separate individuals.
Group A: 5 cc Lignocaine (2%) + 1:200000 Adrenaline + 150 IU Hyaluronidase injected with a 23 no. 3.75 cm needle placed at the junction of the medial 2/3 and the lateral 1/3 of the inferior orbital rim and directed backwards and upwards. Aspiration was done before injection to check I.V. penetration.
Group B: 5cc Lignocaine (2%) + 1:200000 Adrenaline + 150 IU Hyaluronidase injected with a 25 no. 1.5 cm needle in the same manner as retrobulbar injection except that it was directed straight down with the needle buried upto the hub at the skin.
No facial blocks or additional injections for lid akinesia were used. Following the ocular injection massage was done by applying a super pinky ball to exert uniform pressure for 10 minutes with intermittent release of pressure in both groups of patients.
At the end of 10 minutes the eyes were evaluated for:
1) Lid akinesia
2) Globe akinesia
3) Globe anaesthesia
Each of the above was graded on a scale of 0 to +++ as follows:
0 Akinesia/Anaesthesia inadequate to continue.
+ Akinesia/Anaesthesia not ideal but adequate
++ Akinesia/Anaesthesia not ideal but more than
+++ Total akinesia/anaesthesia.
Any complications of anaesthesia were also noted.
Of the 142 consecutive patients of cataract surgery 71 received peribulbar and 71 received retrobulbar anaesthesia. The scale evaluation of each parameter is as tabulated in [Table 1].
There was no significant difference in the assessment between the two methods i.e. peribulbar anaesthesia is as effective as retrobulbar anaesthesia.
However, the incidence of chemosis [Table 2] was significantly higher in the patients who received peribulbar anaesthesia. One patient of Group A had a retrobulbar haemorrhage.
This study proves one point, low volume peribulbar anaesthesia to be as effective as retrobulbar anaesthesia.
In addition to completely eliminating the need for additional facial and lid anaesthesia it also has some advantages over retrobulbar anaesthesia .
1) Injection is less painful.
2) Reduces total quantity of anaesthetic agent required in comparison with the conventional retrobulbar and facial block technique. (However, a recent study has shown a retrobulbar block without facial block also to be effective)
3) Anaesthetic spreads diffusely in the posterior orbit, therefore less posterior pressure and thus a softer eye.
4) Eliminates the risk of retrobulbar haemorrhage.
A clinically insignificant point probably of some concern to a new person would be that the time of onset of anaesthesia/ akinesia in peribulbar technique is 8-10 minutes unlike retrobulbar anaesthesia which shows a quicker onset.
Though the exact mechanism of action is unknown it is probably a combination of direct inhibition of the neuromuscular transmission from orbital diffusion into the extraocular muscles themselves and diffusion into the III, IV, V, VI nerves and the ciliary ganglion.
The method of peribulbar injection utilised in this study is less cumbersome than peribulbar injections used by other authors and simpler than combined retrobulbar and lid injections even when this is used without the facial block.
The complications of retrobulbar anaesthesia are usually due to direct/indirect trauma to the intraconal structures as well as perforation of the globe . All of these are completely eliminated with the use of a 1.5 cm. needle to inject in the peribulbar region, as it is then not possible to even accidentally enter the cone and cause damage to structures within.
Thus peribulbar injection is not only as effective as retrobulbar anaesthesia but safer due to the non-entry into the muscle cone.
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