An Australian woman is blind three days out of every six because her eyes involuntarily shut and she cannot open them, a report has said.

The woman's mysterious medical condition has left doctors puzzled.

Natalie Adler, who experts believe may be the only person in the world with this condition, said she has had this medical predicament since she was 17.

"I woke one Sunday and my eyes were swollen. It was the day before an English exam," the 21-year-old told Melbourne's Herald Sun.

"My eyes started closing intermittently, really randomly, but within a few weeks they were closing for three days [at a time]."

Doctors from the Royal Victoria Eye and Ear Hospital said Ms Adler's condition was baffling.

"She's a one-off and we don't have a diagnosis," said Professor Justin O'Day of the hospital's neuro-ophthalmology department.

"It's unusual to see somebody with this degree of spasming and eyelid closure, especially at this age. There is no known cause."

Professor O'Day said the medical condition blepharospasm, which causes an involuntary closing of the eyes, could be used as a reference but that it did not explain why Ms Adler's eyes closed according to a routine.

Botox treatment

When Ms Adler's eyes are closed, she cannot see at all except through a small slit in her left eye. On the days when they are open, she can see clearly but her left eyelid droops.

For almost two years, doctors treated her by injecting Botox around her eyes, allowing her to see for five days out of six.

But the treatment no longer works for Ms Adler, who also suffers from fatigue and nausea, and she is now hopeful that electrical stimulation tests around her eyes might help.

Ms Adler plans her life around her condition, but still misses some important dates.

"On my 18th birthday, my eyes were closed, but on my 21st they were open, so I had a party," she said.

"Not being able to go to the football or seeing my friends as much is what I miss the most."

- AFP