|Year : 1985 | Volume
| Issue : 1 | Page : 19-22
Clonidine in angle closure glaucoma
Usha Mehta, HC Agarwal, NN Sood
Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, India
F-12, Greater Kailash-I New Delhi-110 048
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Mehta U, Agarwal H C, Sood N N. Clonidine in angle closure glaucoma. Indian J Ophthalmol 1985;33:19-22
The exact mode of action of clonidine hydrochloride-2 (2,6-dichlorophenylamino)-2imadazoline hydrochloride on the B.P. and IOP has excited much controversy. Central and peripheral actions of the drug on the adrenergic components have been postulated. Results of in-vivo experimental studies conducted by Koss and San favoured the involvement of central adrenergic mechanism in causing Clonidine-induced mydriasis. However, no significant effects on accommodation or pupil were observed by other authors.
There has been a limited trial of clonidine by topical route in cases of chronic simple glaucoma ,,, and none at all in cases of angle closure glaucoma.
The purpose of the present study was to assess clinically the efficacy, tolerance and safety of clonidine in cases of angle closure glaucoma.
| Material and methods|| |
38 eyes of 21 patients of angle closure glaucoma (ACG) in different stages were selected for trial with clonidine 0.125% instillation including fellow eyes. The diagnosis in each case was [Table - 1] confirmed by biomicroscopy, tonometry, ophthalmoscopy and gonioscopy. The control group was constituted by 22 eyes of cataract (non-glaucomatous) patients selected to serve as age-matched non-disease controls. No attempt was made to drop out patients with systemic hypertension.
Clonidine powder was dissolved in sterilized distilled water to constitute 0.125% strength of the drug. Basal IOP, BP and pulse rate (PR) were recorded before instillation of one drop of the drug in each eye. The same parameters were recorded at 1/2, 2, 4 and 6 hrs. after instillation Note was made of any local or systemic side effects experienced during the course of the study.
| Observations|| |
I. IO P
Control Group :- The control group of patients had an average drop of 2.45 mmHg and 2.54 mmHg in their right and left eyes respectively [Table - 2]. The peak drop values were detected at 1 /2 hr. recording in 2 eyes, 2 hrs. in 16 cases and 4 hrs. in 4 eyes.
ACG group :- All eyes except one had a drop in IOP with clonidine instillation. For statistical convenience, the eyes were divided into four groups based on their pre-treatment IOP levels. The average drops in IOP varied from 3.21 to 8.99 mmHg in the different groups [Table - 2]. The results of these groups (upto IOP L.45 mmHg) were subjected to one-way analysis of variance. The average drop in IOP was found to be statistically correlatable in the three groups [Table - 2]. No definite linear correlation between the initial pressure levels and the amount of drop with treatment could be obtained. In 22 eyes, the maximum fall was evident at 2 hrs. recording, in 8 eyes at 1 /2 hrs. and in 7 eyes at 4 hrs. After 4 hrs., the IOP levels were found to approach the pre-treatment levels.
One case was excluded from the study on account of persistently high TOP. 3 eyes suffering from chronic ACG were maintaining high IOP with pilocarpine alone. Additional effect was obtained with clonidine drops.
11. Blood Pressure (BP)
Control Group :- A fall in B.P. was recorded in 8 cases at 1/2 hr. and in 3 cases at 2 hrs. recording [Table. 2]. The average fall in systolic pressure was 9.27% and 9.61 % in the diastolic pressure [Table - 3].
ACG group:-The average percentage drop in the systolic values was 8 24% and 6.54% in the diastolic pressure [Table - 3] 10 patients exhibited the maximum fall at 1 /2 hrs and 8 patients at 2 hrs recordings. Two patients had no alteration in BP, 3 cases had fall in systloic pressure and one case had drop in diastolic pressure only. The time courses did not vary to a significant extent in the two groups. However, three patients had an excessive fall in BP . No systemic or local untoward effects could be detected even on direct questioning and BP returned to near pre-treatment levels by the time the study was concluded.
Control group : - The pulse rate was found to slow down in all except 4 controls who showed a rise. The average percentage drop was 4.9%.
ACG groups:- 18 out of 20 cases showed a decrease in pulse rate by 8.77%. A minimal increase was noticed in 4 patients.
The time courses were comparable at 1/2 and 2 hrs. in the two groups.
| Side effects|| |
One patient in the ACG group complained of significant itching after drug instillation, however, no conjunctival hyperaemia could be detected
| Discussion|| |
Classically miotics like pilocarpine and eserine are used for the medical control of intraocular pressure. These drugs, however, give rise to congestion, miosis, cilliary spasm, iritis,. Hyperosmotic agents and acetazolamide are often required to lower the pressure preoperatively. Systemic hypertension and cardiac disease often preclude the use of these drugs. In such cases, clinician feels the need to resort to a drug which is free of systemic and local side effects. The present study with single instillation of 0.125% Clonidine has shown significant results in such cases. The drug has been found to achieve therapeutically significant fall in IOP in cases of angle closure glaucoma (3 21 to 8.99 mmHg.). Whenever an additional effect is required, being water soluble, clonidine can easily be combined with pilocarpine to lower the IOP and corneal oedema in these cases. The duration of action of the drug was 4-6 hrs. with peak effect appearing around 2hrs. after instillation.
It is, however, difficult to comment on the exact site of action of clonidine. In the majority of cases fall in IOP was preceded by fall in BP. Thus, the possibility of a central mechanism of action cannot be ruled out. The percentage drop in IOP (15.74, 23.19, 22.94) was far in excess of the percentage drop in BP (8.24%; 9.27% systolic & in 6.54% & 9.6% in diastolic). This observation does not favour a direct cause and effect relationship between BP and IOP.
The results at pressure levels higher than 45 mmHg. have not been conclusive due to smaller sample size in this range.
We found that the effect on B.P . has been clinically insignificant. However, a transitory fall in BP may be encountered in hypertensive patients. The effects on pulse rate have shown ma-ked scatter and were of no consequence clinically.
| Summary|| |
The present clinical trial of clonidine on 21 patients of ACG age matched with II non-glaucomatous cataract patients has established the safety of the drug far topical use. A therapeutically significant drop in IOP lasting for 4 hrs. has been obtained in cases of ACG. By and large, the effect on B.P. and pulse rate are insignificant. Hypertensive patients may occasionally show an excessive response.
| References|| |
Makabe, R., 1966, Dtsch Med Wochenscbr, 91: 1686.CA ET AL
Hasslinger C , 1969, Klin Monatsbl Augenheilkd, 154: 95.
Koss, M.C. and San, L.C., 1976, Invest, Ophthalmol., 15 (7) : 566.
Harrison, R. and Kaufman, C.S., 1977, Arch. Ophthalmol., 95: 1368.
Counads, H„ 1973, Klin Monatsbl Augenheilkd, 162: 90.
Edelhauser E.M., 1971, Klin Monatsbl. Augenheilkd, 158: 514.
Chandler, P.A., Simmon, R.J. and Grant W.M., 1968, Amer. J. Ophthalmol., 66: 495.
Elder Duke S., 1979, System of Ophthalmology Henry Kimpton 11: 619.
Junemann. G. and Schmidt, G., 1970, Klin Monatsbl Augenheilkd 157: 193.
[Table - 1], [Table - 2], [Table - 3]