The American Optometric Association adopted a resolution at their 2011 House of Delegates endorsing the use of the Horizontal Gaze Nystagmus test by "properly trained and certified" police officers. The AOA "found" that the test is a scientifically proven reliable indicator of intoxication.
The AOA also said it supports the use of optometrists as consultants for law enforcement in the area of the HGN test.
Of course let's not forget the distinction between optometrists and ophthalmologists. An optometrist is must have a Doctor of Optometry degree. An optometrist serves as the primary provider for normal vision problems and for yearly eye exams. An ophthalmologist, on the other hand, is a medical doctor who specializes in the eyes. An ophthalmologist is able to diagnose complicated eye issues and is able to perform laser eye surgery.
You go to the optometrist to get fitted for glasses or contacts. You go to the ophthalmologist when you've got a problem with your eyes. Just who do you think is more qualified to opine on the validity of an HGN test?
But the optometrists believe that training a police officer with no knowledge of the physiology of the eye or of common eye ailments for a couple of hours is sufficient to make that officer an "expert" in the determination, by use of a pseudo-scientific eye test, of whether a motorist has lost the normal use of his or her mental or physical faculties. More than that, the optometrists apparently believe that a two-hour training session on HGN makes a police officer just as qualified as an optometrist to testify as an expert on HGN.
AOA Resolution 1901
You don't suppose that the AOA was just looking for a way to provide supplemental income for its members as whores for law enforcement, do you?