[Note that this review contains a spoiler]
This is one of the quintessential krimis, part of a select group along with The Hexer and The Sinister Monk that would inspire sequels or remakes. It is also noteworthy for having a relatively famous predecessor in the form of the Bela Lugosi vehicle The Dark Eyes of London, one of the few pre-war Wallace adaptations to reach a wider audience; here we might have a quick straw poll on how many have heard of the Weimar German versions of, say, The Hexer or The Squeaker, or have seen them?
It is also important for being the series debut of Alfred Vohrer, who would go on to direct approximately half of all the titles in the series, far outstripping his closest rival Harald Reinl. Putting it another way, Vohrer was to the krimi what Terence Fisher was to Hammer horror, or Mario Bava to the giallo: the man without which the genre would otherwise be just about impossible to imagine.
As Tim Lucas and others have noted, Vohrer and Reinl's directorial styles are different, each man putting his own particular stamp on the material. The thing that really stands out here is how much fun he and his team appear to be having with all sorts of trick shots.
Though some, like the impossible POV shot from inside a man's mouth as he cleans his teeth with a water pick, exist purely as moments of cinematic spectacle, others, like the repeated use of anachronistic irising effects; the device of having a character move in front of and away from the camera in lieu of an obvious cut; or the reflection of one character in another's mirror shades, are more neatly intertwined with the theme of vision running through the film.
Another of Dead Eyes's merits is the sadistic glee with which Vohrer handles the murder set pieces, ranging from the burning of a man's hands with a lighted cigarette so that he plunges to his death down an elevator shaft, to a strangulation to a shot-through the eye a la Argento's Opera some 26 years later. (The killer, along with almost everyone else, wear black gloves, extending the 'fashion to fetish' trajectory identified by Gary Needham in relation to Bava's The Girl Who Knew too Much and Argento's The Bird with the Crystal Plumage; giallo fans will also appreciate some loving close-ups of gleaming knife blades.)
Plot wise it's the usual clotted affair, where just everyone who shows up on screen is improbably inter-related and involved in one way or another, beginning with the recruitment of Karin Dor's Eleanor Ward - a meaningful surname in the Wallace universe, where very few young women appear to have been brought up by their natural parents - to read a barely legible Braille message on a scrap of paper. Said scrap was found in the pocket of a wealthy Australian gentleman fished out of the Thames, an apparent accident of a type that has been occurring with alarming frequency of late, leading to well-founded suspicions of foul play.
But there are also those near certainties you can use to make sense of it all; I say near because as the series wore on the film-makers would occasionally experiment with casting someone against type for an added frisson.
To wit: Joachim Fuchsberger's Inspector Larry Holt is above suspicion and reproach, as is Eddi Arent's comic relief, Sergeant "Sunny" Harvey, while Klaus Kinski's Edgar Strauss is either a suspect or red herring and Dor's foundling the woman-in-peril cum love interest for Fuchsberger. (Is it just me or would anyone else like to see a krimi where it's the Scotland Yard man who is behind the conspiracy as a means of capturing the love interest and the fortune she typically seems about to inherit.)
The nature of Ady Berber's Blind Jack, the henchman who provides the murder gang with muscle is also of interest. A mentally subnormal ape-like throwback, with a tendency towards violence and a string of previous convictions behind him, he's the type of somewhat un-politically correct 1920s Wallace character whose existence in a 1960s German krimi seems daring, naive or something of both in the light of the Nazi period with eugenics, extermination und so weiter.
Since we see Blind Jack in the pre-credits scene, bundling a victim into a van, his role is not a mystery, rather it is the identity or identities of the leaders of the gang, the ones controlling him.
On the krimi-giallo connection it also worth noting here the occupation of one of the gang's leaders, as a presumably Protestant counterpart to the Catholic priests and fake priests who pop up with alarming regularity in the giallo.
Heinz Funk's score again mixes the conventional and the unusual, with some of those not quite sure what they are, or are supposed to be, timbres. It's all in good fun, nonetheless, just like the rest of the film.