No abstract

Astereotaxic atlas of the forebrain and 127, 46-50.The Rat Brain. Baltimore: Williams and Wilkins. lower parts of the brain stem. Actapharmac. lox., 31, Suppl., 1, 26. research, 11. Amsterdam: Elsevier.

tests so that those in whom 5 consecutive measurements showed a difference of more than 3 mmHg were excluded. Measurements in 62 of 94 eyes showed a variation of 3 mmHg or less, and these were considered suitable for the definitive studies. All preparations were administered by a third party to ensure double-blindedness on the part of subject and investigator, and were instilled into the left eye. Intraocular pressure' 3 and radial pulse rate over 1 minute after 5 minutes at rest (sitting) were measured before and at 30, 60, and 90 minutes after drug instillation. Three recordings of intraocular pressure in each eye were taken on each occasion and the means recorded.Two studies were carried out, the first comparing timolol 0 25 and 0 5% with normal saline, and the second pindolol 1%, timolol 0-25%, and normal saline. In each study 12 subjects were studied, no subjects taking part in more than 1 study. They attended on 3 occasions at least 1 week apart for instillation of 1 drop into the conjunctival sac (a) timolol 0.25%, 0.5%, or saline 0. 9%, or (b) pindolol 1 %, timolol 0-25 %, or saline 09 %, given in a balanced design based on 4 Latin squares.

In a preliminary experiment in 12 healthy volunteers, one drop of thymoxamine 0.5% instilled into the conjunctival sac completely reversed the mydriasis produced by phenylephrine 2.5%, 5% and 10% after 20 minutes. In a second study in eight volunteers, thymoxamine 0.5% completely prevented the mydriasis produced by phenylephrine 2.5% and produced a miosis. It also completely reversed the mydriasis produced by tropicamide 0.5%. The mydriatic effect of tropicamide 0.5% plus phenylephrine 2.5%, however, was not completely reversed by thymoxamine 0.5% over a period of 180 minutes. Phenylephrine, tropicamide and thymoxamine are freely available for use by registered optometrists.

A study was carried out in 12 healthy volunteers to determine the effects of 0.25% and 0.5% pindolol eye drops on intraocular pressure. The results showed that both concentrations produced similar and highly significant falls in intraocular pressure after single instillation into the conjunctival sacs, the effect being measured with a non-contact tonometer. No significant changes were found in resting heart rate.