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    Question

    What's the difference between corneo-scleral and scleral lenses?

    The two sound alike and overlap in size. The real difference is where the lens rests: partly on the cornea, or entirely on the white of the eye.

    By the Scleral Lens Team · Last reviewed October 2, 2026 · 7 published sources cited

    The short answer

    A corneo-scleral lens rests partly on the cornea and partly on the sclera, the white of the eye. A scleral lens vaults over the whole cornea and rests only on the sclera, with a pool of saline in between. Corneo-scleral lenses are smaller and can work well for some irregular corneas, while scleral lenses keep the cornea bathed in fluid and avoid touching it, which matters more for fragile or very dry eyes.

    Key points

    • The defining difference is bearing: partly on the cornea for corneo-scleral, entirely on the sclera for scleral.
    • Small studies report good vision with corneo-scleral lenses in keratoconus and after corneal transplant.
    • A scleral lens keeps fluid over the whole cornea, which is why it's often used for severe dry eye and ocular surface disease.
    • Both are rigid gas permeable lenses fitted by a specialist.

    Where each lens rests

    All of these lenses are rigid gas permeable lenses. What separates them is where they bear weight:

    • A corneal lens rests entirely on the cornea.
    • A corneo-scleral lens rests partly on the cornea and partly on the sclera.
    • A scleral lens rests entirely on the sclera and vaults over the cornea.[1]

    This is the classification the Scleral Lens Education Society recommended, and it’s based on how the lens bears on the eye rather than a fixed size.[2] More recent terminology proposes that “scleral lens” means any lens that vaults the cornea and the limbus (the border where the cornea meets the white of the eye) and lands on the conjunctiva over the sclera.[2]

    Older size-based schemes did use diameter. One, summarized in a 2024 paper, labeled lenses of 12.9 to 13.5 mm corneo-scleral.[2] You may still hear a lens called corneo-scleral because of its size, so if the term comes up, ask your fitter whether the lens touches your cornea.

    How a corneo-scleral lens behaves

    Because it’s larger than a standard corneal lens, a corneo-scleral lens can be fitted with only a light touch at the top of the cornea, a better vault over the rest of it, and improved centering.[3] It’s smaller than a scleral lens, and some people choose to try one first. In one small study after corneal transplant, people preferred a corneo-scleral lens over a scleral lens because of handling or cost.[5]

    What the studies show

    The research on corneo-scleral lenses is small, and much of it comes from one research group.

    • Keratoconus. Thirty people were fitted; three stopped before a year. In the 27 who continued, average vision improved from about 20/34 with glasses to 20/20 with the lens, wear averaged about 13 hours a day, and no adverse effects were found at one year.[4]
    • After corneal transplant. Of 11 people, 2 couldn’t tolerate the lens. The other 9 had better vision than with glasses and wore the lenses about 10 hours a day, with no clinically relevant changes in corneal health measures over a year.[5]
    • Severe ocular surface disease. A 14.0 mm corneo-scleral lens was fitted successfully in 10 of 13 eyes with Stevens-Johnson syndrome or graft-versus-host disease. Fitting failed in three, two because of a small eye opening and shortened folds behind the lids, and one because of handling.[6]
    • Healthy eyes. In 30 healthy people with presbyopia (age-related difficulty focusing up close) who wore both a 12.7 mm corneo-scleral lens and an 18 mm scleral lens of the same material, the smaller lens caused less corneal swelling during the day. The authors concluded both designs could work as optical platforms.[7]

    Where each falls short

    Corneo-scleral lenses still touch the cornea. For a cornea that’s fragile, slow to heal, or very dry, that contact can be a problem, and the lens doesn’t hold a full pool of fluid over the cornea the way a scleral lens does.

    Scleral lenses are larger and can be harder to handle. They also put a thicker layer of lens and fluid between the cornea and the air, which reduces oxygen. That’s why corneal swelling is watched closely in eyes with a weak endothelium. See do scleral lenses change the shape of your cornea?

    Other options include standard corneal gas permeable lenses, hybrid lenses, and soft lenses designed for irregular corneas. For side-by-side comparisons, see scleral vs RGP lenses and scleral vs hybrid lenses.

    Common questions

    Is a corneo-scleral lens just a small scleral lens?

    Not quite. Size overlaps, but the definition depends on where the lens rests. If part of the lens bears on the cornea, it's corneo-scleral. If it clears the cornea completely and rests only on the white of the eye, it's a scleral lens, even if it's on the small side.

    Which is better for keratoconus?

    Both are used. Corneo-scleral lenses have done well in small keratoconus studies, and scleral lenses are widely used for keratoconus too. The right choice depends on the shape of your cornea, how comfortable you are, and how your eye responds. Your fitter may try more than one design.

    Which one is better for dry eye?

    For severe dry eye and ocular surface disease, scleral lenses are usually the starting point because they hold fluid over the entire cornea without touching it. Some smaller lenses have also been used for these conditions in small studies, so ask your fitter what fits your eye.

    Keep reading

    What are mini-scleral lenses?

    A mini-scleral lens is a scleral lens that extends only a little past the edge of your cornea. In the classification most often cited, a mini-scleral lens is up to 6 mm wider than the visible colored part of your eye, and a large scleral lens is more than 6 mm wider. Both vault over the cornea and rest on the white of the eye; they just differ in how far they reach. Your fitter picks the size that suits your eye's shape and your condition.

    What is scleral lens vault, or clearance?

    Vault, also called clearance, is the gap between the back of a scleral lens and the front of your cornea, filled with saline. Too little and the lens can touch the cornea as it settles; too much and less oxygen reaches the cornea and vision can be affected. Published reviews cite targets of roughly 100 to 200 or 100 to 300 microns after the lens settles, but they also stress that the right vault is whatever keeps your vision clear, your eye comfortable, and your cornea healthy.

    What are scleral lenses made of?

    Modern scleral lenses are made of rigid gas permeable plastics, such as fluorosilicone acrylates, that let oxygen pass through to the cornea. A material's oxygen permeability is rated as its Dk; scleral lens materials are generally high-Dk. But a scleral lens is thicker than a regular contact lens and sits over a layer of saline, and both reduce the oxygen that reaches your cornea. So lens thickness and fluid depth matter as much as the material itself.

    What is PROSE treatment?

    PROSE is a customized scleral lens treatment from BostonSight, based in Needham, Massachusetts. The device itself is a scleral lens: a gas permeable dome filled with saline that vaults over the cornea and rests on the white of the eye. What sets PROSE apart is its proprietary design software and a structured treatment program with intensive training. It's mainly used for people with severe ocular surface disease or irregular corneas who haven't done well with other options.

    Sources

    1. van der Worp E, Bornman D, Ferreira DL, et al. Modern scleral contact lenses: a review. Cont Lens Anterior Eye. 2014;37(4):240-250. doi:10.1016/j.clae.2014.02.002 pubmed.ncbi.nlm.nih.gov
    2. Keye P, Issleib S, Gier Y, et al. Visual and ocular surface benefits of mini-scleral contact lenses in patients with chronic ocular graft-versus-host disease (GvHD). Sci Rep. 2024;14(1):25254. doi:10.1038/s41598-024-76249-5 pubmed.ncbi.nlm.nih.gov
    3. Asif MI, Kalra N, Tripathi M, et al. Contact lenses for visual rehabilitation in post-keratoplasty eyes: a review. Indian J Ophthalmol. 2025;73(Suppl 3):S369-S383. doi:10.4103/ijo.ijo_2394_24 pubmed.ncbi.nlm.nih.gov
    4. Montalt JC, Porcar E, España-Gregori E, Peris-Martínez C. Visual quality with corneo-scleral contact lenses for keratoconus management. Cont Lens Anterior Eye. 2018;41(4):351-356. doi:10.1016/j.clae.2018.01.002 pubmed.ncbi.nlm.nih.gov
    5. Montalt JC, Porcar E, España-Gregori E, Peris-Martínez C. Corneoscleral contact lenses for visual rehabilitation after keratoplasty surgery. Cont Lens Anterior Eye. 2020;43(6):589-594. doi:10.1016/j.clae.2020.04.009 pubmed.ncbi.nlm.nih.gov
    6. Lee SM, Kim YJ, Choi SH, Oh JY, Kim MK. Long-term effect of corneoscleral contact lenses on refractory ocular surface diseases. Cont Lens Anterior Eye. 2019;42(4):399-405. doi:10.1016/j.clae.2018.10.011 pubmed.ncbi.nlm.nih.gov
    7. Lafosse E, Romín DM, Esteve-Taboada JJ, et al. Comparison of the influence of corneo-scleral and scleral lenses on ocular surface and tear film metrics in a presbyopic population. Cont Lens Anterior Eye. 2018;41(1):122-127. doi:10.1016/j.clae.2017.09.014 pubmed.ncbi.nlm.nih.gov

    Last updated October 2, 2026. Found an error or a newer study? Let us know and we'll correct the page.