Impairment of contrast sensitivity in long-term lorazepam users.

RATIONALE

Oculomotor balance and contrast sensitivity are known to be impaired after an intake of a single dose of lorazepam. To the best of our knowledge, these effects have not been explored in long-term users of lorazepam, despite the potential importance of such deficits in everyday life.

OBJECTIVE

We tested the ophthalmological effects and contrast sensitivity for static stimuli in long-term lorazepam users.

MATERIALS AND METHODS

There were 15 lorazepam users and 15 sex-, age- and education level-matched control subjects tested, using a simple blind procedure.

RESULTS

The ophthalmological effects were scarce, with a discrete exophoria. Visual acuity was preserved. Contrast sensitivity, however, was more markedly impaired, consistent with the effects of an acute dose of lorazepam. The effects were not correlated with anxiety or sedation.

CONCLUSIONS

The results are discussed in terms of their possible impact on everyday life. As visual acuity does not allow the detection of the impairments that are observed in the present study, it is suggested that a more systematic exploration of contrast sensitivity be carried out in long-term users of benzodiazepines.