From its literal combining form, glassy eyes mean that the eyes appear to be glazed or shiny. To be exact, it refers to an appearance of a fixed staring, wide eyes but listlessness. Those who suffer from viral conjunctivitis or low blood sugar would manifest the symptom of glassy eyes. In addition, not blinking the eyes frequently can cause the eyes to become dry and lifeless, giving rise to glassy eyes. Therefore, if you do not want to get glassy eyes, you should control the consumption of drugs and alcohol, because they would depress the central nervous system and make you blink less frequently, hence appearing the glassy eyes.
Well, generally speaking, it is normal to have glassy eyes. First, you should know that if a person's eyes appear shiny or have a glassy appearance that means he/she is suffering from glassy eyes. In other words, when someone have glassy eyes, his eyes will have a feeling of listlessness, and the eyes are unfocused, and without any luster. For causes, the habit of not blinking the eyes too often can lead to it. Because of it, it will cause the eyes to become dry, and leading to glassy eyes. Also, some people who are heavy drinkers will have glassy eyes too.
When you are told to have the glassy eyes, your eyes look watery because of the infection and other things. You'd better take great notice of your health in eyes. You'd better go to see the doctor and find the real reason to cause the glassy eyes. Then you could accept the medical treatment to cure it. You will get the bright eyes again.
Glassy eyes can be understood as a fixedly staring and wide-eyed appearance. Originally, I though this to mean watery eyes wherein there seems to be a transparent film covering the eyes, but this was wrong. It's just that the eyes are so wide and unblinking that they simulate a pair of glasses. Glassy eyes is one of the criteria for determining if a person has been driving drunk. Alcohol depresses the nervous system, and affects the eyes' functions, such as size control and blinking. If a person's has been found driving with wide eyes that don't blink, along with other criteria, that could be a candidate for arrest for substance abuse.