Slipstream

Slipstream is set in a dystopian future, following a global environmental disaster. A voice over at the beginning of the film explains that a doomsday event, the "Convergence, has destroyed the balance of the world's weather systems, with the result that the jet stream has expanded to the planet's surface, with the surface scoured by winds far surpassing anything ever seen before, destroying cities and entire nations. Many bizarre communities have survived in the valleys and caves, some regressing to primitive states, others embracing advanced technologies. Many are isolationist and some are attacked by marauding bandits. Ground transport is no longer possible due to the atmospheric conditions, but skilled pilots can travel by air, following the fierce winds and travelling with their flow, a practice known as "riding the slipstream". The remnants of society have therefore become airborne; most now reside on high precipices or in caves beneath the howling Slipstream. It is also stated that nobody has ever been to the ends of the Slipstream, because atmospheric conditions there make human survival impossible.
The film opens with an unnamed man (Peck), running down a canyon, being harassed by an aeroplane, which drives him onto a precipice. The plane lands and its occupants, two bounty hunters, Will Tasker (Hamill) and Belitski (Kitty Aldridge), chase the man and shoot him through the arm with a grappling hook. The fugitive looks at his arm, but seems intrigued rather than distressed. Tasker pulls on the rope, and the man tumbles down the side of the canyon, but once again is not harmed. Immediately after his fall, the fugitive recites the words of famous World War II aviator and poet John Gillespie Magee, Jr., "I have slipped the surly bonds of Earth - put out my hand and touched the Face of God.", from the poem High Flight.
The bounty hunters take the man prisoner and fly to a busy civilian airstrip, where he stands beside them, handcuffed, as they eat in the airstrip's diner. There they encounter Matt Owens (Paxton), a hustler and smalltime arms dealer. He makes a pass at Belitski and she nearly breaks his arm, and he then tries to sell contraband grenades to Tasker. It is then revealed that Tasker and Belitski are part of the remnants of a law enforcement agency, trying to keep the peace in what is left of society. Byron is wanted for murder, and they are bringing him to justice. Tasker seizes Owens' weapons, but as the pair are leaving, Owens kidnaps Byron so that he can claim the large reward for himself, and they flee, but not before Belitski shoots Owens with a dart, both poisoning him and planting a tracking device in his body, enabling Belitski and Tasker to follow the fugitives.
Owens and Byron land at the home of a cult of cave-dwellers who worship the Slipstream and who have recently been under attack by bandits. After Byron heals a boy blinded by cataracts, Owens realises that Byron is more than he appears to be. Byron then reveals that he is a humanoid android. When the wind cult finds out about Byron's abilities, they tie him to a massive kite, and let the wind decide what to do with him. The bounty hunters arrive in the middle of a windstorm, and Belitski and Owens are forced to work together to get Byron down. Belitski then allows Byron and Owens to get away, along with another visitor to the valley, Ariel who soon becomes emotionally attached to Byron. Ariel takes them to her people, a group of hedonists, who inhabit a fortified underground museum. Byron and Ariel spend the night together in an African Savannah exhibit, while Owens gets drunk and hooks up with a local girl. Later, Byron explains more of his past, revealing that the man he killed was his master. Byron also excitedly tells Matt that he has slept for the first time, and that he dreamed of a land at the end of the Slipstream, inhabited by other androids.
Soon after, having tracked the trio to the museum, Tasker and Belitski force entry, killing the guards and some of its inhabitants. After beating the Curator (F. Murray Abraham), Tasker forces the rest to find the fugitives. Byron is captured, and Owens is knocked down. Belitski confronts Owens and shoots him in the chest with a dart; Owens retaliates by knocking her out, but then realises that the dart is the antidote to the poison, so instead of killing her, he handcuffs her to a bed while he sets off after Tasker. A shootout ensues in which Tasker kills Ariel. Enraged, Byron pursues Tasker to his plane. Tasker shoots Byron, to no effect, so he then tries to run Byron down as he takes off, but Byron manages to jump on, and smash his way into the cockpit. The pair struggle, but as Byron is on the verge of killing him, Tasker quotes the Magee poem and Byron relents. He then attempts to regain control of the damaged aircraft by using the control wires, but he is unsuccessful, and it crashes. Tasker is killed, but Byron, being an android, survives. He returns to the museum to find that Belitski and Owens are now a couple. The film ends with Byron leaving to seek his 'promised land'.

Question: What does Byron heal the boy of?
Answer: Cataracts