|Year : 1982 | Volume
| Issue : 4 | Page : 227-228
Timolol for glaucoma
Eye Department, Medical College, Amritsar, India
Eye Deptt Medical College, Amritsar-143001
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Singh D. Timolol for glaucoma. Indian J Ophthalmol 1982;30:227-8
Philips discovered that beta-adrenegic blocking agents used in cardiology could reduce intraocular pressure. It took almost a decade to advance from the systemic use of beta-blocking agents to arrive at a local glaucoma treatment that did not cause any local or general side effect. The following is the list of 11 beta-blocking agents that have been studied by various workers for ocular hypotensive effects
Very potent drugs : Sotalol and Timolol Their action is stronger than pilocarpine.
Drugs with intermediate potency : Pindolol Oxprenolol, Bupranolol, Labetolol and Propranolol. Their action is comparable to pilocarpine.
Less active drugs : Atenolol, Tiperanolol, Butidrine and Metoprolol.
Sotalol is 18 times inferior to Timolol, when used as local drops but equally effective in I/V experimental studies. That promotes Timolol to the highest place, as regards intraocular pressure reducing activity.
Mode of action
Timolol causes reduction in aqueous formation. The action is different from the carbonic anhydrase inhibitors and therefore the two drugs can have additive effect. This is an important advance. Facility of outflow is not affected. Pupil size is not affected, therefore cases of narrow angle glaucoma, without a peripheral iridectomy are unsuitable for Timolol therapy.
Timolol is available in two strengths : 0.25%and 0.5%. The medicine needs to be instilled only once or twice a day. Only one drop is to be instilled. Every drop is costly and wastage should be avoided.
Duration of Action
The action of Timolol lasts much longer than 12 hours. Therefore twice a day is the maximum needed. Many patients need only one drop in 24 hours.
| Materials and methods|| |
We have used Timolol in the 40 patients (22 Chronic simple glaucoma, Aphakic glaucoma : (2 patients had I.C.L.), 12 Secondary glaucoma following intraocular inflammation)
The choice of the patients for Timolol was made as follows
1. Where pilocarpine therapy had failed.
2. Where pilocarpine + diamox therapy had failed to control intraocular pressure.
3. Where conventional therapy with, with pilocarpine alone or pilocarpine -1- diamox was causing unwanted symptoms.
| Observations|| |
Intraocular pressure in the patients varied from 26 and 58 mm Hg. Addition of Timolol achieved a fall of intraocular pressure ranging from 20 to 40 %.
1.0 P. was controlled in 31 out of 40 eyes. Addition of Timolol saved 7 eyes from surgery.
In 6 cases addition of Timolol made the ingestion of diamox unnecessary. Follow up : was of 4 months to 20 months. Side effects noted were nil.
| Discussion|| |
Advantages of Tirnolol over miotics are : no pupil constriction, no accommodation, no ocular discomfort, no retinal detachment, no shallowing of anterior chamber, no cataract formation and no iridocyclitis. The advantages over epinephrine : are no pupil dilatation, no maculopathy in aphakics, no conjunctival hyperaemia, no adrenochrome deposits and no ocular irritation. The advantages over carbonic anhydrase inhibitors are effective topically, no CNS effects, no GI effects, no kidney stones, no parasthesias, no acidosis and no weight loss. Thus Timolol has come out to be an important weapon in "therapeutic arsenal" of the ophthalmolo , gists in their fight againt glaucoma. This weapon is however not yet imported in India. We therefore, will have to depend upon bow . and arrow technology of pilocarpine and surgery for the time being.
The possibility of fighting glaucoma by Timolol, is especially welcome, since the mode of action is different from the medicines currently available. The action is also additive with other medicines. Therefore it will be possible to treat a greater number of patients by medical means and save them from surgery and its natural complications.
| References|| |
Philips, C.I., Howitt, G. and Rowlands, DJ. 1967, Brit. J. Ophthalmol, 51 : 222.