Blindness
Blindness was the condition of lacking visual perception due to physiological or psychological factors. There are varying degrees of blindness, ranging from minor visual impairment to total loss of eyesight.

Causes of blindness 
Most visual impairments are caused by disease and malnutrition, though blindness could also be caused by various abnormalities, injuries, genetic defects and poisoning. Temporary vision loss could also be a side effect of some vaccinations. ()

Genetic defects – Geordi La Forge was born blind due to a birth defect
Physiology – Some species, like the Aenar, were born blind
Injury – Martok's eyesight was impaired when he lost an eye in a battle with Ikat'ika
Magnetic fields – Prolonged exposure of humanoids to the intense magnetic fields on Galorndon Core resulted in synaptic breakdown, which rendered La Forge blind even though his VISOR worked perfectly. ()
Other intense energy – Tuvok was blinded by a detonating chroniton torpedo in an alternate timeline. () 
Spock was rendered temporarily blind after intense light was used to destroy a flying parasite infection, his sight saved only due to his inner eyelids. () 
Dukat was temporarily blinded by a burst of energy released from the Book of the Kosst Amojan by the Pah-wraiths. ()
  asked  whether he was trying to go blind after the captain admitted in 2263 of the alternate reality that he was downing the last of the Saurian brandy they'd picked up on Thasus. ()

Attitudes towards blindness 
On Earth, the practice of institutionalizing the blind in asylums had a history extending back into the 9th century, and it was not until the 18th century that authorities created schools where blind children, particularly those more privileged, could obtain an education in specialized settings. Despite the negative connotations associated with blindness, many blind Humans throughout history led rich lives despite their handicap, including the famous poets Homer and John Milton, artist Claude Monet, and musician Stevie Wonder. ()

Romulans killed children who were born with blindness or other such defects. When La Forge told Bochra that he had been born blind, he asked incredulously "And your parents let you live?", stating that the Human race was weak because "You waste time and resources on defective children." ()

On some planets, genetic engineering was utilized to ensure that blindness is a condition of the past. On Moab IV, someone with such a disability would have been terminated as a fertilized egg. ()

Adaptive technologies for the blind 

 A sensor web was a garment of finely woven sensor units, typically utilized by the blind during the 23rd century. The web could be worn naturally over everyday clothing, and emitted low-level sonar scans undetectable to the Human senses. The web then translated the return signals into media perceptible by the trained wearer. Dr. Miranda Jones wore such a web which she used, along with her telepathic prowess, to hide her blindness from others. () 

The VISOR was an external medical device used in the Federation to aid patients who had suffered loss of eyesight. The VISOR detected electromagnetic signals across the entire EM spectrum, and transmitted those signals to the brain through neural implants in the temples of the individual via delta-compressed wavelengths. Geordi La Forge, born blind, was given a VISOR after his fifth birthday. ()

Ocular implants were internal, surgically-implanted medical devices which replaced or enhanced the eyesight of an individual. Geordi La Forge received ocular implants in 2373, which eliminated his need for an external VISOR. The Borg also utilized ocular implants as enhancements for their drones. (; )

The tactile interface was a feature of 24th century LCARS panels, which altered the normally flat panels (intended to be read) so that beings with visual impairments could use the consoles. ()

Blind species 
Aenar, intelligent beings native to the planet Andoria, were completely blind, though they had highly-evolved telepathic abilities that largely compensated for it.
The Tiberian bat was a blind, winged mammal.

See also 
 Color blindness

External links 
 
 
de:Blindheit
Medical conditions