Vision Impairment - What is it?

Everyone's vision is different. There is no exception for those who have vision impairments  - every impairment is also different. There are a few distinct ways that vision impairments usually manifest though, so we do have a good idea of what they can look like. 

Different areas of the eye may be affected, which can localise the impairment. This can be the case for a person may lack central vision due to macular degeneration. Sometimes, the way light passes through the eye can be affected so that their vision lacks detail or sharpness - this can happen in the case of cataracts. We also see a lot of cortical visual impairment - this is when there is no defect in the eye itself, but there is an inability for the brain to process the vision that is being sent to it via the eyes. In this case, vision can appear to be scrambled or may fluctuate while being processed.

There's also the classic question - do blind people see black? 

No! It's a fair question to ask, but it is a misconception based upon our own experience of seeing. When a person has a vision impairment, patches of their vision may not be providing their brain with the information that is there. In its absence, the brain may actually confabulate (create or make up) vision. This means that such patches may have nondescript texture, colour or a seamlessness from areas of good vision that can make it hard to identify what we can or cannot see.

In people who experience no vision, there is no visual information being conveyed to the brain. This means that rather than a blackness, there is nothing. This is why people who have no vision learn to use their other senses for many daily tasks - usually they are working just fine! There are lots of ways that we can adapt to our senses and it's not necessary to be able to see to live a long, happy and normal life.