In this question the answer given is prescribing spectacles

In this question the answer given is prescribing spectacles. The explanation says that the impairment has happened already and spectacles given to limit the disability. My doubt is refractive error will itself be a disease so why is it not secondary prevention?

Refractive error is not a disease , it’s a sequale of a change or a pathological state like lengthening/shortening of the eyeball, change in refractive power of two or more meridian of the cornea.

The spectacles prevent further disability but do not treat the underlying cause. Hence it’s an example of disability limitation not specific protection