Always encourage eye contact. When you say his name and he looks at you, that very moment praise him for his eye contact by saying “Good eyes” and immediately give him a reinforcer.
If he does not make eye contact after saying his name do not keep repeating his name. Using hand over hand, raise his hand to your eye and as he follows his/your hand gets to your eye say, “good eyes” and give reinforcer. Fade your prompt as soon and as much as you can.
If hand over hand does not work, use the reinforcer by bringing it toward your eyes, beside your eyes.
Using the words “good eyes” will help later to promote good eye contact with objects he needs to look at as he works. You could later use the word “eyes” to prompt him to look at the object as you point to what he needs to look at. So, the words “eyes” could be your prompt. Your goal will be for him to associate the term eyes with him needing to look.
With that said I don’t believe eye contact is solely necessary for him to understand or pay attention to what is said or even what is in his environment. I do believe there are times and in certain individuals it is a challenge for them to look at you and process what you are saying or the environment around him.