What type of nystagmus may indicate the presence of a dissociative anesthetic drug such as PCP?

The presence of vertical nystagmus is commonly associated with the effects of dissociative anesthetic drugs like PCP. Vertical nystagmus refers to the involuntary movement of the eyes in an up-and-down pattern, which can indicate a specific type of impairment often linked to certain substances. PCP, in particular, is known to cause significant alterations in motor control and perception, and vertical nystagmus can be a clear sign of such influence.

Furthermore, while resting nystagmus does occur, it is not specifically tied to the use of dissociative anesthetics and instead may result from a range of other conditions. Understanding these nuances can aid officers and those trained in SFST in accurately assessing a driver's impairment and making informed decisions based on observable signs.