Media reports indicate that an Australian woman is blind three days out of every six because her eyes involuntarily shut and she cannot open them. This is a mysterious medical condition that has puzzled doctors.

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)," said Adler.

Doctors from the Royal Victoria Eye and Ear Hospital said 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."

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 Adler's eyes closed according to a routine.

When Adler's eyes are closed, she can't 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.