There’s nothing worse than being hit over the head with an allegory. Books are forever at it, but within the subtle didacticism of prose they can pull it off. Film, on the other hand, with its demand for psychological realism, struggles badly with allegory, often leaving only malformed ciphers and eat-your-veg pedagogy.

It’s hardly surprising then that Blindness, the hotly anticipated new film from Fernando Meirelles (The Constant Gardener), is crippled by a debilitating tension between reality on screen and allegory in the story. Adapted from a dystopian fable by the Portuguese Nobel laureate José Saramago, it describes an unnamed cosmopolitan Every City where White Sickness, a sinister blindness virus, attacks overnight, transforming the government into totalitarian crazies and sending into brutal makeshift prisons great swaths of the population.

Among them are an ophthalmologist known only as Doctor (Mark Ruffalo), his wife, known as Doctor’s Wife (Julianne Moore) and a host of memorable symbols acting as people. The Brazilian actress Alice Braga plays the archetypal saintly prostitute, but is simply called the Woman with the Dark Glasses, presumably because the Tart with a Heart didn’t fit with the sombre mood.

The majority of the film unfolds within the packed prison, a former mental asylum that, without any outside intervention and under the kindly guidance of Doctor, becomes a template for democratic governance. Until, that is, the arrival of the prison bad boy, Bartender (Gael García Bernal), who sets up a dictatorship in the adjacent ward and begins his own Mugabe-style reign of terror. It’s all very ponderous and po-faced, and should really have accompanying “Geddit!” flash cards at the end of every scene.

Meirelles, perhaps aware of this, goes on a technical bender, lathering each frame in milky-white light to capture, you know, the blindness. His actors do their best, and Moore certainly remains a powerhouse presence whenever she’s on camera. But mostly they struggle to be seen beneath the leaden messages.

18, 120 minutes

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