No, no eyes!

leading from

Creating the Alien 

and

Physicality of the alien humanoids head

Giger's Alien head at the Giger museum

a) Bulbous Eyes

The creature from Giger's painting Necronom IV had slanted bulbous eyes perhaps inspired by motorcyclist goggles and it became too much like a Hells Angel, (also with this creatures bulbous head from the front it looked a bit like depictions of reports of extra-terrestrials from Zeta II Reticuli known as The Greys which would not have been easily known at the time)

b) Removal of the eyes

Giger and Ridley were staring at the alien head, and Ridley put a plastic bucket over its head. Giger's response was "Ah, no eyes. It's very good"

Giger decided that it looked more frightening with no eyes and that it looked more dangerous when you never know where it's looking, and so they went ahead with this.  

c) Glowing lamps behind the eyes 

The next step was for Ridley and Giger to convince the producers that the eyes should be removed, and getting as far as that, then the producers wanted him to include lamps behind the eyes but he decided "No, no eyes".

They producers said to him to "Please try it" but they came to realise that it didn't work.

quote source

1. H.R.Giger: The big problem was with the [full-grown] monster. In the first design, head had big black eyes, but somebody said he looked too much like a Hell's Angel, all in black with the black goggles. Then I thought it would be even more frightening if there were no eyes. So when the camera comes close, you see only the holes of the skull. Now that's really frightening. Because even without eyes he always knows exactly where his victims are, and he attacks directly. (Cinescape vo.3 no.9, p22)
2. H.R.Giger: All these beasts are blind. I think it is very frightening to have beasts with no eyes. At first they wanted it to have eyes with lamps behind them. Other people always wanted that  but I decided No, no eyes. They said please try it but it didn't work. I think the final version looks quite believable. (Film Monsters # 158, p31)
3. H.R.Giger: And all these beasts are blind. I think it's very frightening to have blind beasts. At first they wanted eyes with lamps behind them. But I said no, no eyes. They said please, but it didn't work. (Warren Present Alien Collectors Edition, p35)
4. Stewart Jamieson: Did you immediately know how to design the creature
   HR Giger: Ridley had already decided it should be based on Necronom IV, which I then refined. Ridley and I convinced the producers to remove its eyes because it was more dangerous when you never know where it's looking. ( December 2003 Total Film , p14)
5. Interviewer: Firstly Ridley, tell me about the Alien movies, just gets people really excited
   Ridley Scott: Well, it narrows down to on very special thing, and that's the alien himself. I think the alien is really primordial, disturbing, and it's got no eyes, people don't con....if you look, the alien, the original alien had eyes in the design, then Giger and I were staring at it and I put a plastic bucket over its head and he said "Ah, no eyes. It's very good" and so we had an aspic forehead (TORYmax)