Abstract
Forty patients with an intraocular pressure (IOP) between 30 and 49 mmHg in either eye (57 eyes) were recruited into a trial of timolol 0.25% versus timolol 0.5%. Patients were randomised to receive the two concentrations of drug in the order ABA or BAB. The study period was 12 weeks for each patient, with changes in drug concentration at 4 and 8 weeks. IOPs were measured at the same time every 2 weeks. Mean IOP of both eyes was used, excluding any eyes with initial IOPs of less than 30 mmHg. There was no difference between the 2-week and 4-week pressure readings, which were therefore combined. There was no statistically significant difference in the initial IOPs of the two groups (0.5%, 33.45 mmHg; 0.25%, 32.63 mmHg) nor in the initial fall in IOP with either concentration (0.5%, 12.03 mmHg; 0.25%, 11.31 mmHg). Furthermore, changing from one concentration to the other had no significant effect on IOP. Mean IOPs over the whole study period averaged 21.12 mmHg for timolol 0.25% and 20.75 mmHg for timolol 0.5%. Again these differences were not statistically significant. The statistical power of the study was estimated to exceed 85%. The authors suggest that there is no justification for use of the 0.5% strength, which is more expensive and has no advantages.
Similar content being viewed by others
Article PDF
References
Mills KB . Blind randomised non-crossover long-term trial comparing topical timolol 0.25% with timolol 0.5% in the treatment of simple chronic glaucoma. Br J Ophthalmol 1983;67:216–9.
Uusitalo RJ, Palkama A, Stjernschantz J . A study of the efficacy of two commercial preparations of timolol maleate with special reference to side effects. Acta Ophthalmol (Copenh) 1985;63:634–41.
Novack GD . Ophthalmic beta-blockers since timolol. Surv Ophthalmol 1987;31:307–27.
Hickey-Dwyer M, Campbell SH, Harding SP . Double masked three period crossover investigation of metipranolol in control of raised intra-ocular pressure. J Ocular Pharmacol 1991;7:277–90.
Davson H . Physiology of the eye. London: Macmillan, 1990:50–1.
Ray WA, O'Day DM . Statistical analysis of multi-eye data in ophthalmic research. Invest Ophthalmol Vis Sci 1985;26:1186–8.
Gore SM, Altman DG . Statistics in practice. London: British Medical Association, 1982:6–8.
Oldham PD . Measurement in medicine: the interpretation of numerical data. London: English Universities Press, 1968:148–52.
Gill JS, Zezulka AV, Beevers DG, Davies P . Relation between initial blood pressure and its fall with treatment. Lancet 1985;1:567–9.
Mottow-Lippa LS, Lippa EA, Naidoff MA, Clementi R, Bjornsson T, Jones K . 0.008% timolol ophthalmic solution: a minimal-effect dose in a normal volunteer model. Arch Ophthalmol 1990;108:61–4.
Author information
Authors and Affiliations
Additional information
Annual UK sales figures for timolol (0.25% and 0.5%), hospital and retail combined: 0.25%= 1,179,900 units= 39%; 0.5%= 1,826,700 units= 61%.
Rights and permissions
About this article
Cite this article
Campbell, S., Hickey-Dwyer, M. & Harding, S. Double-masked three-period crossover investigation of timolol in control of raised intraocular pressure. Eye 7, 105–108 (1993). https://doi.org/10.1038/eye.1993.22
Issue Date:
DOI: https://doi.org/10.1038/eye.1993.22
Keywords
This article is cited by
-
Long-term drift and timolol therapy: possible role for pulsed therapy
International Ophthalmology (1992)