system
Given the following post, respond as if you're commenting on Reddit:
human
How do doctors know the prescription for glasses for babies/children who are too young to do the usual sight tests?
gpt
They can map the shape of the eye pretty easily and get about 90% of the way to knowing the prescription. Then they need feedback from the patient for the fine tuning. Babies just can’t give that last little part that doesn’t matter much.