September 6, 1971
Robert S. Hepler, MD; Ira R. Frank, MD
Abstract
To the Editor.— It is accepted widely that the physiologic effects of smoking marihuana are not well known, despite an acknowledged high incidence of usage. Even the President of the United States has called for a major effort to study drug effects in a scientific manner. In an attempt to investigate the effects of marihuana smoking upon the human visual system, complete ocular examinations were performed in a group of youthful subjects, before and one hour after smoking. Selection of subjects, medical and other safeguards utilized, and details of the protocol will be presented in a later publication.
The purpose of this letter is to present preliminary data concerning the most impressive change observed so far, namely, a substantial decrease in intraocular pressure observed in a large percentage of subjects. Applanation tonometry was performed by the same experienced examiner, using the same tonometer for each pair of observations.
Marihuana was Mental Health, and assays proved the concentration of tetrahydrocannabinol to be high (0.9%). Two grams were smoked by each subject using an ice cooled water pipe. It is our hope that further investigations by clinicians and basic scientists will be stimulated by the observations recorded in the Table. The possible implications, including the mechanism of action, and even possible therapeutic action in the treatment of glaucoma, are obvious.
