Inspirational 15-year-old Charly Sissons lost her sight altogether in the space of a week and doctors still don't know why.
Her vision has improved slightly but is restricted to grey dots and shadows and doctors hope her sight will return.
In the meantime she is still pursuing her dream of representing Great Britain at windsurfing and has carried on competing against able-bodied windsurfers thanks to someone guiding her on a radio.
Charly, of Bourne Road, Essendine, said: "I first started getting blurred vision and it felt like I was seeing through black rings. Then a few days later I couldn't see out of my right eye and I had blurred vision in the other.
"The next day it seemed to be slowly clearing up. But a few days later everything started going grey. It was frightening but I thought it was just a version of a headache."
For a while Charly could only see blackness but she is noticing improvements. She said: "If I calm down and concentrate I can see some things. When I'm going really fast on the board I can see white lines going past my eyes."
Charly is on a phased return to The Robert Manning College in Bourne and is being allowed time to recover and adapt. She can carry out normal day-to-day tasks but needs assistance when leaving the house.
Charly said: "My friends have been understanding and caring. They try not to mention what's been on TV and instead talk to me about music and things I can listen to."
The windsurfing fanatic is taking the positives from her circumstances. She said: "Losing my sight made me more confident and I feel as if I'm even faster. My hearing is much more clear now – which isn't always a good thing!"
Charly is determined to carry on competing in the sport that has been her passion since a nine-year-old when she went on a school trip to Tallington Lakes. And it has been a positive focus for her over a difficult few weeks.
She vowed: "Whatever happens, nothing will get in my way."
Charly has represented the East of England team and wants to step up to international class. Next year she will aim to qualify as an instructor.
At the weekend she represented Ipswich-based windsurfing team the Alton Water Wipeouts in the T15 Champions Cup at Rutland Water. She was assisted by a "buddy" boat to monitor her and the team finished eighth out of nine competing.
Proud mum Gill, 53, said: "She's stubborn-minded and determined. She comes alive when she's able to go out on the water."
Dad Steve, 50, added: "She just will not give up. She's heading in the right direction and we're both extremely proud of her. The world doesn't exist when she's out on the water."
Robert Manning principal Laurence Reilly said: "This was a very unfortunate occurrence for such an active student, but I am pleased that she is making good progress and will hopefully make a full recovery.
"Charlotte is a conscientious and able student who is set to do well in her GCSEs next summer. She has made every effort to keep up with her studies."