What the phrase means
In general insurance terms, medically necessary care is care needed to diagnose or treat an illness, injury, condition, or disease, or its symptoms, that meets accepted standards of medicine.[1]
For contact lenses, plans use it to separate two situations:
- Elective contacts: you prefer contacts to glasses. Glasses would work.
- Medically necessary contacts: an eye condition means glasses can’t give you adequate vision, or the lens is treating the eye itself.
Scleral lenses are usually prescribed for the second reason. But whether your plan agrees is decided by its written criteria, not by the type of lens.
Conditions published criteria commonly list
These come from payer policies we read. They show what plans tend to look for. Your plan’s list may be shorter, longer, or worded differently.
A vision plan’s list. Davis Vision’s criteria, dated July 2026, say medically necessary contact lenses are available only for these diagnoses:[2]
- Keratoconus, documented with topography, OCT, or corneal mapping (preferred) or keratometry
- High prescriptions: an eyeglass prescription of at least -8.00 or +8.00 diopters, with best corrected vision in glasses of 20/40 or worse and at least two lines of improvement with contacts
- Anisometropia: a difference of at least 3.00 diopters between the two eyes
- Aphakia (no natural lens in the eye)
- Aniridia (underdeveloped or absent iris)
- Irregular astigmatism of 2.00 diopters in either eye, with a further measurement requirement
The same document says the criteria “do not imply or guarantee approval” and are only valid for three months from the date published.[2]
An earlier version of the same company’s policy, from 2022, also listed scleral lenses for symptomatic dry eye disease, but only after a patient had failed a comprehensive trial of other treatments such as non-preserved artificial tears, prescription anti-inflammatory drops, and punctal plugs.[3] That shows how criteria for the same company can change between versions.
A medical plan’s list. Aetna’s medical policy considers scleral lenses medically necessary prosthetics when they’re used as moist corneal bandages for severe ocular surface disease, including corneal stem cell deficiency (such as after Stevens-Johnson syndrome or chemical injury), neurotrophic corneas, severe dry eye (such as from Sjögren’s syndrome or chronic graft-versus-host disease), and corneal exposure.[4] For keratoconus and other irregular corneas, it covers the evaluation and fitting, but not the lenses under plans that exclude contact lenses.[4]
Medicare. Medicare’s national coverage policy describes scleral lenses used to protect the eye in severe dry eye as a prosthetic device that “would be covered as a prosthetic device in the rare case” when used that way.[5] See the Medicare guide for more.
The proof plans ask for
A diagnosis alone usually isn’t enough. Published policies ask for evidence.
- Test results. Keratoconus criteria call for corneal topography, OCT, or keratometry.[2] High-prescription criteria call for specific prescription and vision measurements.
- A statement of medical necessity. The 2022 Davis Vision policy required a signed statement of medical necessity that documents the specific indication and is accompanied by the medical record, including relevant history, examination, and test results, plus the lens prescription.[3]
- History of other treatments, for conditions like dry eye where a plan expects other options to be tried first.[3]
Your fitter’s office normally prepares this. Your part is to make sure they know which plan to send it to and what that plan asks for.
What to ask your plan
- Do you have written criteria for medically necessary or visually required contact lenses? Can you send them to me?
- Is my diagnosis on the list? What measurements or test results do you need?
- Is this handled under my medical plan or my vision plan?
- Does the fitter need prior authorization before ordering lenses?
- What does the benefit pay, and does it cover replacements?
- When were these criteria last updated?
What to ask your fitter
- Which of my diagnoses and test results support medical necessity?
- Have you submitted medically necessary claims to my plan before?
- Will you send the documentation and request prior authorization if it’s needed?
- If the plan says no, will you help with an appeal?
Common questions
My doctor says I need scleral lenses. Doesn't that make them medically necessary?
To your doctor, yes. To your insurer, 'medically necessary' is a coverage decision made against the plan's own written criteria. Your fitter's documentation has to show that you meet those criteria.
Is keratoconus always considered medically necessary?
Keratoconus is on the published lists we've seen, but plans usually require proof, such as corneal topography, and some cover the fitting under the medical plan while leaving the lenses to a vision plan. Ask your plans how they handle it.
Does dry eye count?
Sometimes. Some medical policies cover scleral lenses used as a bandage for severe ocular surface disease, including severe dry eye from conditions like Sjögren's or graft-versus-host disease. Some vision plans require that you've already tried other dry eye treatments. Plain dry eye without that history may not qualify.
Do I have to qualify again for replacement lenses?
Often there are separate rules for replacements. Some policies don't cover lenses that are lost, damaged, or replaced only because your prescription changed. Ask before you need one.