The clearest proof of the boundary comes from the plan documents themselves. A vision plan’s general exclusions typically list medical treatment of eye disease or injury, eye surgery to correct vision including LASIK, drugs or medicines, and vision therapy. If a service treats a disease, it is medical care, and it runs through your medical insurance rather than your vision plan.
The two coverages also use different networks, even when the same company name appears on both cards. A practice can be in-network for your routine exam and out-of-network for your medical visit — on the same day, in the same building — so it is reasonable to ask us to check both. The most common surprise bill happens when a routine glasses exam turns up something medical, such as raised eye pressure or a retinal change: the refraction stays a vision-plan service, while working up that finding is medical care with its own copay and possibly a deductible.
Cataract surgery and LASIK fall outside the vision plan for different reasons. Cataract surgery with a standard lens is a medical benefit, covered under Medicare Part B or a commercial medical plan. LASIK is elective vision-correction surgery that medical plans generally do not cover either — what a vision plan may offer for it is a discount, not coverage.