|Year : 1985 | Volume
| Issue : 1 | Page : 15-17
Clonidine in chronic simple glaucoma
Usha Mehta, HC Agarwal, NN Sood
Dr. Rajendra Prasad Centre for Ophthalmic Sciences, A.I.I.M.S. New Delhi, India
S-12, Greater Kailash-1 New Delhi-1 10048
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Mehta U, Agarwal H C, Sood N N. Clonidine in chronic simple glaucoma. Indian J Ophthalmol 1985;33:15-7
Ophthalmologist is often faced with the problem of side effects of pilocarpine in the form of myopia, ciliary spasm and headache etc. In the event of development of resistance (tachyphylaxis) to pilocarpine, the only alternative drug available is epinephrine and sometimes timolol. It is a common observation that epinephrine takes a few weeks before producing its maximum effect. Unforeseen delays in the availability of timolol are inevitable too. Epinephrine is often contraindicated in the glaucoma age group on account of systemic hypertension. On such occasions, there is a pressing need to switch over to a drug which is free of the side effects, has a quick action and is easily available.
The topical use of clonidine in cases of chronic simple glaucoma was first suggested in 1969 by Hasslinger. Subsequently, experimental and very few clinical trials have been conducted. The results indicate that clonidins can reduce lop by 10-40% in conditions of raised lop and its action persists for at least four hours. The minor changes in the blood pressure were dose related and had no clinical significance. No ocular side effects have been reported. The use of clonidine in Angle Closure Glaucoma is under publication.
The present study was aimed at establishing the potential use of clonidine in the treatment of chronic simple glaucoma (Open Angle Glaucoma OAG). The efficacy, duration of action and side effects were studied with a single dose instillation of 0.125% solution of clonidine hydrochloride.
| Material and methods|| |
Twenty cases of chorine simple glaucoma with basal intraocular pressure (IOP) over 21 mmHg were selected for the study. All the cases had their diagnosis established after ocular examination, ophthalmoscopy, tonometry, gonioscopy and field charting. Ocular history included the details of the past and present therapy. Systemic hypotension and cardiac disease were ruled out by history and examination. Systemic hypertension was not considered a contraindication.
The control group was constituted by eleven cataract patients belonging t o the same age group i e. 45-65 years, same as the disease group. I. O. P., B. P. and pulse rate were recorded before and 1/2, 2, 4 and 6 hrs. after instillation of single drop of 0.125% clonidine (in distilled water) into the eyes under study. The patients were asked questions regarding local or systemic side effects felt during the study.
| Observations|| |
1, lop :
Control Group : A drop in lop was observed during the course of the study. The average drop was 2.45 mmHg and 2.54 mm Hg in the right and left eyes respectively [Table - 1].
OAG Group ; In this group of 20 patients, two patients had high IOP with pilocarpine therapy and one patient was uncontrolled on epitrate drops. The patients were divided into four groups based on their pre-treatment values of I.O.P. [Figure 1].
The average drop in IOP varied from 5.35 mmHg to 11.10 mmHg [Table - 1]. The peak effect was observed in 5 eyes at 1/2 hour recording, in 25 eyes at 2 hrs and in 6 patients at 4 hrs recording. The pressures were nearly the same as pre-treatment levels at 6 hrs recording.
II. B. P.
Control Group : The subjects exhibited a mean fall of 9.27'X 0 in their systolic pressures. All except two patients had a corresponding drop in diastolic pressures. The average drop was 9.61 % [Table - 2].
OAG Group : Out of the twenty, 17 patients had a drop in systolic pressure and 14 patients had a drop in diastolic pressure during the trial. Others showed no alteration. The mean drop calculated in terms of percentage was 7.73;0 systolic and 7.92% diastolic [Table - 2]. One patient had no change in either. The fall was recorded at z hr in 11 patients and at 2 hrs in 8 patients.
III. Pulse Rate
Control Group : All except four patients bad a slowing of pulse rate after clonidine instillation. The average drop was 4.9%. Four patients exhibited a rise in pulse rate.
OAG Group : All except five patients showed a slowing of pulse rate after clonidine. Four patients had a rise and one patient had no alteration of pulse rate. The percentage drop was 4.9% in this group.
| Discussion|| |
Clonidine has shown encouraging results in single dose instillation study in cases of chronic simple glaucoma. The intraocular pressure lowering effect has been significant. The duration of action of the drug is 4 hrs with peak effect around 2 hrs of instillation. These results agree with the observations of Heilmann and Harrison et a1. Remarkable feature of this drug was the easy acceptability on account of lack of local or systemic side effects. The absence of side effects was also recorded by German workers,. Clonidine has demonstrated an additive action with pilocarpine in 2 patients and with epinephrine in one patient.
The drop in blood pressure induced by clonidine was mild in most of the cases and had no clinical bearing. In one hypertensive patient, the drop was excessive but was not associated with any symptoms. The duration of its action on blood pressure was symmetrical in the disease and control group (P<0.05). The change in BP was transient and reverted back to pretreatment values by 4-6 hrs. However, sudden drop in BP in a patient on anti-hypertensive therapy may lower the perfusion pressure in the eye. In such cases, clonidine may be used with extra caution.
We did not come across the phenomenon of 'biphasic response' reported by Allen and Langhan in 1976 in a study on conscious rabbits. An inhibition of central sympathetic outflow by clonidine was thought to be responsible for the biphasic response which could be exaggerated by regional adrenergic denervation. Failure to elicit any such response may indicate the role of peripheral site of action of clonidine on adrenergic receptors in the ciliary body vasculature and in the angle of anterior chamber. The ability of clonidine to bind to peripheral alfa adrenergic receptors was shown in the in-vitro studies on rabbit eyes. Theoretically, simulation of the former would reduce the secretion of the aqueous while stimulation of the latter receptors would facilitate the outflow of aqueous. Tonographic studies may be carried out to analyse the point further.
In view of the observations of this study, clonidine would prove a useful adjunct in medical therapy of the chronic simple glaucoma especially in the following circumstances :
1. When miosis is not desired as in glaucoma with nuclear cataract.
2. In young patients, it is an alternative to pilocarpine (pilocarpine induced myopia).
3. In the event of development of resistance to a drug e.g pilocarpine.
4. When it is desired to shift from one drug to another, clonidine may be used in the transit period.
5. When epinephrine is contraindicated in cases of systemic hypertension.
6. When combination therapy is required clonidine may be combined with pilocarpine or epinephrine.
| Summary|| |
Clonidine in 0.1250.0 dilution has been found to be a useful adjunct in the treatment of chronic simple glaucoma by topical drugs. The major advantages are easy availability, acceptability and adequate response to drug. The results of this study would help launch a wider long term trial of clonidine in chronic simple glaucoma.
| References|| |
Hasslinger, C., 1969, Klin Monatsbi Augenheilid, 154: 95.
FIeilmann,K., 1970,K1in Monatsbi Augenheilkd, 157: 182.
Harrison, R. and Kaufman, C S., 1977,.Arch. Ophthalmol. 95 : 1368.
Mehta Usha, Agarwal. H. C. and Sood, N.N. 1985, under publication.
Merte, H. J. and Heilman, K., 1974, Stuttgart, West Germany, Ferdinand Enke Verlag.
Conrade H , 1973, Klin Monatsbi Augenheilkd, 162 : 90.
Edelhauser, E. M., 1971, Klin Monatsbi Augenheilkd, 158-514.
Allen, R. C. and Langham, M. E., 1976, Invest Ophthalmol 15 : 815.
Neufeld, A H. and Page, E. D., 1977, Invest. Ophthalmol , 16:1118.
[Table - 1], [Table - 2]