No: Myths & Misconceptions.
18 Myths About Hypnosis
The eyes must be closed for hypnosis to be present.
Closing the eyes does not imply hypnosis. The eyes can actually be opened in a hypnotic state.
There are many different styles of hypnosis. In a traditional hypnotic induction it is more accepted to ask a client to keep her eyes closed to minimize distractions, yet one of the techniques used to deepen the state is eye opening and closure invented by Dave Elman in order to perform what is called a fractionation. Every time a subject opens and closes her eyes she goes deeper into the state of hypnosis, which, believe it or not, has a compounding effect, i.e. it multiplies the effect of a hypnotic suggestion. Nevertheless, you would still expect a hypnotic subject to keep her eyes closed after deepening is achieved.
In conversational hypnosis, which I am also certified in, and with most NLP techniques, it works quite differently: a client may have her eyes open at all times and still go into a very profound trance in order to create a beneficial subconscious change.
In stage hypnosis, it is a combination of styles and often a hypnotist asks the client to open her eyes after a certain suggestion is given. When it happens, the client talks and bahaves as if nothing happened but still acts upon the suggestion with her eyes open. For example, a partial amnesia to forget the number 5 can be given during the induction and when the client comes out of it and opens her eyes, number 5 is still temporarily erased from her mind. In order for this to work, however, there must be a genuine desire to act upon the suggestions and if it is not there, i.e. the client does not believe this process is beneficial for her, hypnosis cannot occur against her will.