Hello again, and thanks so much for your reply and update.
I'm sorry to hear that the vet believes she may have hydrocephalus or the fontanel has reopened. Typically, the fontanel closes within a couple of months after birth, but in some cases, it can take up to a year. Open fontanels usually don't cause any kind of brain damage, but if the vet feels she may be blind at this time, she may have experienced a head trauma you were not aware of, which either reopened the fontanel or it wasn't completely closed. The soft spot is really quite small.
If she is blind, blind cats can live normal lives as long as they can navigate their environment and you don't move any furniture, etc. I'm glad to hear that she's eating well, now, and I'm sure you're helping her get along as well as possible, with the litterbox, etc.
Has any imaging been done, like an x-ray, ultrasound or CT of her head/brain, so more information can be learned? I'm sure you're continuing to consult with your vet to get a definite diagnosis and then, see if any treatment is needed.
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Also, please keep me posted on how your kitten is coming along and if you find out any new information. Thanks!