Year : 1982 | Volume
: 30 | Issue : 4 | Page : 269--271
Quantitative assessment of ocular anaesthesia by anesthesiometer, orbiculomyometer distantometer and tonometer
HS Chundawat, MK Punjabi
Deptt. of Opthalmology, R.N.T. Medical College, Udaipur and S.M.S. Medical College, Jaipur, India
H S Chundawat
Dept, of Ophthalmology, R.N.T. Medical College Udaipur, Rajasthan
|How to cite this article:|
Chundawat H S, Punjabi M K. Quantitative assessment of ocular anaesthesia by anesthesiometer, orbiculomyometer distantometer and tonometer.Indian J Ophthalmol 1982;30:269-271
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Chundawat H S, Punjabi M K. Quantitative assessment of ocular anaesthesia by anesthesiometer, orbiculomyometer distantometer and tonometer. Indian J Ophthalmol [serial online] 1982 [cited 2020 Apr 4 ];30:269-271
Available from: http://www.ijo.in/text.asp?1982/30/4/269/29446
An ideal anaesthetic should have an early onset, sustained effect and with minimum side reactions. For ophthalmic surgery it should produce complete akinesia, analgesia, anaesthesia, dilated pupil and lower intraocular tension.
There is no unanimity about the strength of lignocaine hydrochloride to be used and whether alone or in combination with adrenalir and hyaluronidase. Higher concentrations may not add to the effectiveness. The present study was conducted for critical, quantitative evaluation of presently used anaesthetic and to recommend the balanced ocular anaesthesia.
MATERIALS AND METHODS
One hundred and twenty patients were the subjects for this study. Lignocaine 1%, 2% and 4% alone and in combination with epinephrine (1:80,000) and hyaluronidase (50 1.U./ ml) were tested. The behaviour of corneal sensations, orbiculus oculi muscle power, change in pupillary size and intraocular pressure were measured quantitatively by using anesthesiometer, orbiculomyometer and distantometer tonometer respectively.
Anesthesiometer used for this study was reconstructed using the principle of Boberg Ans which consisted of graduated cylinder with a piston and nylon thread attached to it. The free end of the nylon thread was touched to the cornea and touch sensations felt by the patient were recorded. Definite touch point was just twisting of nylon thread in place of its straightness. The readings so obtained in millimeters were converted into milligrammes by conversion table. The force required by touch sensations to be appreciated is inversely proportional to the external length of the thread. Size of thread was 0.112 mm. which covered about 4 to 10 epithelial cells containing nerve endings.
Orbiculomvometer was reconstructed on the principle of Muller and Droescher which measured force required to close the eye lids by amplitude of deflection of a pointer which moves on scale. The unit of force is calculated in grammes by using conversion table. The instrument consisted of an eye speculum, to one limb of which was attached an eight centimeter long pointer and to the other end a scale which was marked from zero to sixty.
Lignocaine hydrochloride (Gesicaine Suhrid Geigy) was the anaesthetic used in various strengths and effects were studied in the following headings :
Group A (50 cases) -
Surface analgesia : 1%, 2% and 4% drops of each concentration were instilled in the conjunctival sac and loss of corneal sensations were studied by anesthesiometer.
Group B (40 cases) -
Retrobulbar block : 1 % and 2% concentrations of 2 nil were used alone and with hyaluronidase and epinephrine. Group C (30 cases)
Facial nerve block: by Obrien's method 1% and 2% concentration of 4 ml were used along and with hyaluronidase.
OBSERVATIONS AND DISCUSSION
Surface Analgesia - Present study show that corneal sensations disappeared with I drop of Lignocaine 1 % and 2% in an average of 3.5 minutes and duration of anaesthesia was maintained for 10 . 15 minutes. With Lignocaine 4% corneal sensations disappeared in 2 minutes and the effect remained for 10-20 minutes. Intraocular tension and pupillary size were not affected.
Retrobulbar block - 1% solution brought a change in pupillary size from an average of 3.85 mm to 5.40 mm. The effect was observed after 10 minutes and was maintained for total period of 82.7 minutes. The average change in size of pupil after retrobulbar injection of ligno caine 2% alone and when used in combination with epinephrine and hyaluronidase, gives 3.30 mm, 3.20 mm, and 3.05 mm respectively. These changes were maintained for 124, 157.5, and 146.5 minutes respectively. Contrast in pupillary dilatation was quite obvious from 1 % to 2% solution alone and when combined with potentiating agents.
Hypotony, relaxation of extra ocular muscles, constriction of arteries and dehydration of vitreous are the advantages of epinephrine and hyaluronidase.
Intraocular tension recorded an average reduction of 4.46 mm Hg. (Schiotz) with Lignocaine I % : while it was 7.42, 7.51 and 7.50 mm Hg. with Lignocaine 2% alone, combined with epinephrine and hyaluronida respectively.
Average loss of ocular movements wit retrobulbar injection of 2% lignocaine in com bination with epinephrine and hyaluronidas was complete, much quicker (2.01 minutes and lasted for longer (151.0 minutes). Where motor akinesia was incomplete, started Jai (6.16 minutes) and lasted for a short (42.5 minutes) with 1 % solution.
Facial nerve block - By O'berien's method paralysis of orbicularis oculi took place within 5 minutes with Lignocaine 1 % and in 1 . 2 minutes with Lignocaine 2% alone and combined with epinephrine and hyaluronidase, Total duration was 30-45 minutes (with 1% solution) and 90-105 minutes with 2% solution in combination with epinephrine and 60-75 minutes with combination of hyaluronidase.
It is concluded that the use of 4% lignocaine for surface anaesthese is the best. Lignocaine 2% when combined with epinephrine and hyaluronidase has an early onset, sustained and complete effect after retrobulbar injection and facial nerve block. The effect remained for quite a sufficient period during which intraocular surgery could be performed well, With 1% and 2% solutions alone the effect was delayed and incomplete and lasted fora t shorter duration.
Authors express their sincere thanks for kind guidance and help rendered to them by Late Dr. Saket Bhatnagar, and Professor R,G, Sharma.
|1||Boberg Ans, 1955, Brit. J. Ophthalmol„ 39:105. |
|2||Muller and Droescher, 1938, : Text Book of Ophthalmology, Duke E'der London, p. 5165.|