Inside the eye is a lens that focuses light on the back of the eye, or retina. Vision occurs at the retina. The structure of the eye is similar to a camera, which has a lens to focus light on the film. A cloudy or opaque lens is called a cataract.

Cats and dogs can become intoxicated by cannabis in various ways, most commonly by eating edibles (e.g., baked goods, candies, chocolate bars, and chips containing cannabis), or by ingesting cannabis directly (in any form). Pets can also be exposed to second-hand smoke. A small amount may affect one pet more than another, so there is no official safe level of exposure. Many of the signs of intoxication are neurological, including disorientation, dilated pupils, and hyperactivity. In severe cases, tremors, seizures, and coma can result. Regardless of the method of exposure, accurate and complete information from the owner is imperative to treat the patient successfully.