Blindness was the condition of lacking visual perception due to physiological or psychological factors. There were varying degrees of blindness, ranging from minor visual impairment to total loss of eyesight.
Burning one's eyes, for example with taranium, could lead to such a state of blindness, (TV: "Devil's Planet") as could, in the case of Time Lords, prolonged exposure to the vacuum of space. The Twelfth Doctor himself became blind after walking outside in a vacuum without a helmet for too long. The Doctor's attempts at restoring his sight failed, leaving him unable to see at all. (TV: Oxygen)
Some conditions, like cataracts, could lead someone to effectively be "practically blind", as they could not differentiate between colour and light. King Henry VIII, for example, saw everything as a blur, even with glasses, until the Third Doctor cured his cataracts in 1539. (PROSE: Hiccup in Time)
As his visit to Ravolox was reviewed during his trial at Space Station Zenobia, the Doctor protested that it was "obvious to a blind speelsnape" that he only worked for Drathro under duress. (TV: The Mysterious Planet)
Blindness in humans Edit
Ada Gillyflower was blind from her mother, Winifred's, experiments with red leech poison to create an antidote from the toxins. Winifred claimed that she was blinded by her father in a drunken rage. (TV: The Crimson Horror)
Parkinson was a blind vicar who lived in Shoreditch in 1963. His blindness was caused by a German mustard gas attack at Verdun during World War I. (PROSE: Remembrance of the Daleks) He prepared a grave for the Hand of Omega at the request of the First Doctor, and later presided over the burial of the coffin containing the Hand at the request of the Seventh Doctor. He stated to the Doctor that he had noticed the Doctor's voice had changed since they last met, to which the Doctor replied, "Yes it has changed, several times". (TV: Remembrance of the Daleks)
Rita-Anne Smith was blind. In 2002 she broke her neck and died when she tripped on carpet Mickey Smith forgot to fix. In a parallel universe in 2007, Rita-Anne Smith was also blind, and after her grandson died Mickey fixed her carpet so she would not suffer the same fate as her counterpart and stayed with her, allowing her to believe he was Ricky. (TV: Rise of the Cybermen)
Blindness in other species Edit
Davros was left blind after he was crippled in a Thal attack. (AUDIO: Davros, Corruption) He was later able to see via a cybernetic third eye embedded in the middle of his forehead. (TV: Genesis of the Daleks) At some point, his eyes were at least physically restored, although he still relied on the cybernetic eye. (TV: The Witch's Familiar)
Daleks could be blinded if their eyestalk was destroyed or if the lens was covered. (TV: "The Escape", Destiny of the Daleks, Resurrection of the Daleks, Revelation of the Daleks, Remembrance of the Daleks, The Parting of the Ways) However, by the time of the Time War, the Daleks had developed a means of protecting their eyestalks. (TV: The Stolen Earth)
Mother Finsey was blinded when the Master attempted to kill her after they had spent some time travelling together. She was able to learn how to compensate for her lack of sight, and eventually created a set of lenses that allowed her to 'see' in infrared, as well as giving her an artificial version of the Master's hypnotic ability (AUDIO: The Transcendence of Ephros).
Some species were naturally blind. The Cimmerian race was totally blind and had no concept of either sight nor eyes. They accidentally blinded Orllensa, Mike Ferras and Haliard, but later healed them. (AUDIO: Embrace the Darkness) Slithergees were also naturally blind, but compensated for this with a keen sense of smell. (AUDIO: Flip-Flop) The Masters of Dorada lost the organs for sight and hearing when they became disembodied brains, but could still sense others' thoughts. (PROSE: The Dream Masters)
The Time Lady Solenti had been blind in her current incarnation for ninety-one years since she witnessed some catastrophic event that damaged her eyes. However, the neural pathways controlling her sight were still intact in her brain, with the result that she would regain her vision when she regenerated, although even after this was confirmed she decided to remain in her current incarnation until she absolutely had to change rather than regenerate just to regain her sight. (PROSE: The Suns of Caresh)
The Twelfth Doctor was left blind after being exposed to the vacuum of space. (TV: Oxygen) He subsequently compensated for this by using the sonic sunglasses to transmit information directly to his mind, giving him a framework to allow himself to walk and interact with others without anyone recognising his loss of sight, the glasses presenting the Doctor with basic images[disputed statement] of his surroundings and quick biological details of anyone around him. (TV: Extremis) His eyesight was eventually restored by the Monks when Bill Potts made a deal with them to restore the Doctor's vision in exchange for surrendering Earth to them when the Doctor was trapped in a lab with an explosive and could only escape if he could see the locking mechanism. (TV: The Pyramid at the End of the World)