Except that we know from the autopsy that she was blind, because her visual cortex was destroyed
Is it impossible that dehydration caused this?
A good question, but it couldn't been caused by the dehydration. The autopsy report says: "Of particular importance was the hypoxic damage [damage caused by lack of oxygen] and neuronal loss [the nerve cells were gone] in her occiptal lobes [where important visual centers are located] which indicates cortical blindness."
A quick translation: the lack of oxygen led to the death of the nerves in the part of the brain that "processes" vision. The only time she was known to be without oxygen was during the original cardiac arrest the night she collapsed.
Yes it is a good question.
[Acute cortical blindness: a reversible complication of acute kidney failure in a child with burns]
An 11 year old boy was admitted to the Department of Pediatrics Medical School of Vienna with 2nd and 3rd degree burns covering 30% of his body.
He presented with complications--high fever, vomiting, diarrhea and dehydration--which had led to acute renal failure.
After 6 hemodialyses renal function recovered after two weeks and the patient entered a polyuric phase. In connection with a transient dehydration the patient showed a sudden bilateral cortical blindness.
The computerized tomogram (CT) showed vague evidence of an occipital cortical ischemia. We assume that several factors have played a role in this sudden occurrence. As a result of hypovolemia and coincident anemia and electrolyte inbalance, cerebral edema and cortical tissue hypoxia with emphasis in the occipital cortical region developed in the brain possibly already damaged by burn injury. A complete reversal of the clinical state was achieved. The patient was discharged with normal vision and normalized renal function. www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=6835679&dopt=Abstract
She wasn't getting much oxygen or oxygenated blood for who knows how long those last few days or hours of her dehydration.