Final answer:
To prevent strabismus from developing into amblyopia, the nurse should advise patching the unaffected eye, as this strengthens the affected eye by forcing it to work harder.
Step-by-step explanation:
To prevent strabismus from developing into amblyopia, the instruction that a nurse should include is to patch the unaffected eye. This is because patching forces the affected eye to work harder, thus strengthening it and preventing amblyopia. Administering mydriatic eye drops daily is not specifically related to treating or preventing amblyopia. Prescription glasses may assist if strabismus is due to a refractive error, but they don't directly prevent amblyopia. Antihistamines would not be relevant in this case unless there was an associated allergic component affecting vision. It's important to receive a personalized treatment plan from a healthcare provider to address any underlying causes and prevent progression.