On the list of campy sci-fi, this film ranks high. Although it was a British import, it had many elements of American sci-fi (namely, a passable plot and low-budget special effects). The difference is that the acting is more credible, Forrest Tucker notwithstanding.
The plot revolves around mysterious deaths in the Alps, near an Austrian town called Trollenberg. It seems several mountain climbers have met grisly deaths, including one at the very beginning who gets his head ripped off. They don't show it, but seeing the body from the neck down, covered in blood is effective enough. Also, for some reason, a telepath named Anne Pilgrim (played by Janet Munro, who went on to do such movies as "Darby O'Gill & The Little People" and "Swiss Family Robinson" before dying of acute myocarditis at age 38) feels the need to stop at Trollenberg instead of continuing on to Vienna. She and her sister Sarah (Jennifer Jayne) are part of a mind-reading act. While on their train, they incur the interest of Alan Brooks (Forrest Tucker playing another fish-out-of-water role as a serious leading man), a man with hazy United Nations connections, who is heading to Trollenberg for mysterious reasons.
It seems aliens are trying to acclimate themselves to Earth's atmosphere so they can take up shop. They use a radioactive cloud to hide their activities and kill mountain climbers who get too close. They also take some of the climbers and make them into zombies so they can kill potential enemies. In this case, it's Anne Pilgrim who, as a telepath, can sense the aliens' presence.
The action takes place at a brisk pace, simply because the aliens need to get acclimated before their activities invoke a response from mankind. We also learn that Tucker and Professor Crevett (Warren Mitchell), head of the Trollenberg Observatory that first noticed the cloud, were involved in a similar situation in the Andes Mountains in South America. They were too late to stop that situation as the aliens bailed when it got too hot. Now, however, they may get the chance to put an end to them for good.
The acting is crisp, save for Tucker. Veteran British stage actor Lawrence Payne does a nice turn as Phillip Truscott, a newspaper reporter and love interest for Anne. If you can ignore the fact that he was assigned to investigate the Andes incident and just happens to be in town for this invasion, that is. Particular menacing is Andrew Faulds as Dewhurst, a local climber who becomes a zombie. With an eerie sneer, he decapitates a climbing companion, kills two would-be rescuers with a climbing pole to their heads, then attacks Anne Pilgrim twice, getting bashed in the head, then shot for his trouble.
The film has a few glaring flaws. The special effects are low-budget. Close-up scenes of the aliens (as giant eyeballs, hence the title) are creepy, but when they move up the mountain, they're laughable. When Tucker and Payne hit them with Molotov cocktails, they burn up like matches (a common complaint I have about British sci-fi is the way they don't even attempt to make explosions or fire look like anything other than match heads flaring). Another flaw is when Brett, Dewhurst's climbing partner, is killed, rescuers find his cabin door barred from the inside and the windows locked and intact. Yet, his head is missing. A neat trick. Also, when UN bombers torch the mountain to get at the crawling eyes, the whole attack looks totally cheesy.
A few notes in parting. Janet Munro is not related to Caroline Munro ("Golden Voyage of Sinbad," "The Spy Who Loved Me"), despite rumors to the contrary. Also, the original title of the movie is "The Trollenberg Terror." "The Crawling Eye" was the American title. For some reason, American audiences were believed incapable of understanding the cerebral titles of British films and needed titles that were sensational. Thus, "The Quatermass Experiment" became "The Creeping Unknown"; "Quatermass 2" became "Enemy From Space"; "Quatermass and the Pit" was changed to "Five Million Years to Earth," and "Trollenberg Terror" became "The Crawling Eye." Finally, this film was first shown on a twin bill with "The Strange Case of Planet X" (changed, of course, for American audiences to "Cosmic Monsters"). It also starred Forrest Tucker, who is even more wooden than in "Crawling Eye." If you want to see some good acting from Tucker, stick to "The Abominable Snowman of the Himalayas" where he plays a selfish, conceited and boorish American businessman clashing with Peter Cushing while in pursuit of the fabled monster.
Review by pv71989 from the Internet Movie Database.