First comprehensive eye examinations are recommended at 6 months of age, where the optometrist is evaluating your baby for any signs of ocular health issues (like retinoblastoma, congenital cataracts, blocked tear ducts), checking for binocular vision (strabismus / eye turns), and are looking for refractive error (prescription) that is outside of normal ranges for their age (farsightedness, astigmatism, or nearsightedness).
We have many ways to check the health and vision of a 6 month old, even though they cannot talk!