More than one-third of UK health experts are not aware of Charles Bonnet syndrome - CBS - a condition which can cause vivid, and sometimes frightening, hallucinations.
A poll of 1,100 health experts - including GPs, doctors and optometrists - found 37 per cent were not aware of CBS.
When you lose your sight, your brain gets less information from your eyes than it’s used to so sometimes it makes up for this by creating hallucinations.
Of those who are aware of it, one-tenth of health workers admit they have a very limited understanding of the condition.
CBS is widespread among the blind and partially sighted with research suggesting about one in five people who experience sight loss develop it - meaning at least one million people in the UK are living with the condition.
The research was conducted by Esme’s Umbrella, the only UK charity which offers support to those who live with CBS and their families.
Nina Chesworth, who has yet to receive a diagnosis after four-and-a-half years, spoke about her experience with the condition: “I first started experiencing the symptoms of CBS straight after I lost sight in my left eye after a traumatic incident.
“After waking up from surgery, I was seeing a lot of blaring colours, but I was just told it was my mind playing tricks on me.
“As time went on the colours began to develop into shapes, then ghost like images, faces which were Picasso-esque, zombies and animals,” she said.
“But my visions became more and more complex and I couldn’t cope any longer - at this point I spoke with my GP, but they had not heard of it.
“This was four and a half years ago and I still haven’t had an official diagnosis.
“My ophthalmologist also didn’t diagnose it, and after seeing several specialists, they all had different views of what it might be and what was causing it. Only one said they would look into the possibility of CBS after I told them what it was.
“This became so intense and frightening, so I researched what the visions could mean - and it wasn’t until I found out about Esme’s Umbrella and reached out to them until it started to make sense.
Esme’s Umbrella put Nina through to Professor Dominic Ffytche, the UK’s lead researcher into CBS, who explained all about the condition and got her in touch with others experiencing the condition too.
Nina said: “It was a massive relief knowing it wasn’t a mental health issue and it is a possible natural effect of sight loss. This made me feel confident again to deal with my situation.”