An optician makes and fits glasses, and isn’t a doctor.

An optometrist prescribes the lenses that you’ll need, and can also do some tests for a few eye problems. While optometrists are called doctor, they aren’t a medical doctor (sort of like a chiropractor).

An ophthalmologist is a medical doctor who specializes in the eye.  If there is reason to believe you are prone to cataracts it would be an ophthalmologist that you’d see to have it checked.