How to check someones eyes when there under the influence of narcotiics?

Pupils ...: Pupils can be smaller and more sluggish in reacting to light, but you have to know what normal looks like to note the difference. And if someone has chronically been using, might not notice much of anything unless the doses get really high.

Pupils: Depending on the narcotic, the pupils may be larger or smaller than usual (normal), and the eyes are typically very blood shot. Of course there are many other symptoms to consider besides what the eyes look like, such as tremors, mood swings, frequent nose bleeds, appetite changes, weight loss/gain, in attentiveness, seizures, unusual body odor, lack of grooming, change in school/job performance.