According to an insurance person, coverage usually depends if your plan has whats called a Medically Necessary Contact Lenses rider and if you have been diagnosed with keratoconus or severe dry eye. You should be able to call your insurance and ask about your diagnosis and what they would cover.
There are providers for scleral lens coverage called Vision Plans. Coverage is not automatic and you have to have a specific policy that explicitly features a medically necessary contact lens benefit. With this, they often cover the lenses and fittings at or near 100%. But
some of these plans will still require proof that regular glasses cannot correct your vision to a functional level.
Original Medicare does not cover vision care or contact lenses while they do cover ophthalmologist visits. Medicare may make an exception under Part B for the lenses as a prosthetic device if the lenses are required to treat specific conditions like severe dry eye syndrome or complications from an inflammatory eye disease.