Been experiencing vision problems like halos. what age do cataracts appear?

Any age: While cataracts can occur at any age, they typically begin to appear in the 50s. Vision does not generally start to suffer until the 60s in most people, but it can start earlier. Halos around lights are certainly a common symptom, but they are not exclusive to cataracts. See an ophthalmologist for a dilated eye examination to determine the cause of your vision problems.

At any time: Most people develop visually significant cataracts in their 60's, although by time you're 40 most people probably have mild changes consistent with early cataracts. You can be born with cataracts as well. Seeing an ophthalmologist would confirm whether you had cataracts or not.