1. Six young male volunteers were exposed to
sarin vapour (isopropyl methyl phosphonofluoridate) at a concentration of 0.5 mg/m(3) for 30 min (concentration time (Ct) 15 (mg min)/m(3)).2. The resulting clinical syndrome was treated by instilling 0.06 ml of a 1%
solution of
cyclopentolate into the conjunctival sac.3. Visual acuity, retinoscopy, objective and subjective refraction and pupil sizes were noted before the trial, after exposure to
sarin and
after treatment with
cyclopentolate.4. No appreciable difference was demonstrated between the control objective retinoscopy values and those obtained after
cyclopentolate treatment of the clinical syndrome induced by
sarin. Reduced near visual acuity was observed in some subjects treated with
cyclopentolate as compared with acuity after exposure to
sarin alone, considered to be due to the partial cycloplegia produced by treatment. Visual acuity after exposure to
sarin alone was improved in some instances by the
miosis produced.5. It is suggested that unless full dark adaptation is a consideration, treatment of the ophthalmic condition resulting from exposure to this dosage of
sarin should be reserved for those experiencing distressing ocular symptoms.