How to read these numbers
Most keratoconus research on scleral lenses comes from a single clinic, looking back through records or following a few dozen people forward for months. Several studies only include eyes that were fitted successfully, which makes outcomes look better than they would for everyone who tries. Vision is usually reported on the logMAR scale, where lower is better and 0.0 equals 20/20. We note the design and size of each study so you can judge how much weight to give it.
For the general picture across all conditions, see scleral lens outcomes research. For how common keratoconus is and how often it leads to a transplant, see keratoconus statistics.
Vision
Every study we found reported a large, statistically significant improvement in vision with scleral lenses compared with glasses.
| Study | Who | Design | Vision before → with scleral lenses[1][2][3][4][5] |
|---|---|---|---|
| US, 2020 | 157 eyes of 86 people, worn successfully for at least a year | Retrospective | 0.50 → 0.08 logMAR (glasses vs scleral) |
| US, 2010 | 30 eyes of 19 people fitted successfully, out of 32 people evaluated | Retrospective | Median 20/40 → 20/20 |
| Turkey, 2020 | 29 eyes of 24 people | Clinical series | Decimal acuity 0.40 → 0.93 |
| India, 2024 | 28 eyes of 14 people | Prospective, 3 months | 0.47 → 0.03 logMAR |
| Turkey, 2026 | 95 eyes of 61 people, all previously cross-linked | Retrospective | 0.95 → 0.14 logMAR |
Sources: US 2020[1], US 2010[2], Turkey 2020[3], India[4], Turkey 2026[5].
A 2025 systematic review pooled five studies (463 eyes) published after 2020 with at least three months of follow-up. Average acuity improved from about 0.50 to 0.53 logMAR at baseline to 0.08 to 0.09 with scleral lenses. The reviewers rated the methods of the included studies as variable and called for randomized trials with longer follow-up.[6]
Who gains most is less settled. In the 95-eye Turkish study, eyes with moderate keratoconus and a cone just off center gained the most, though the off-center group was small.[5] Low-contrast vision (seeing gray on gray, as at dusk) also improved in the 29-eye Turkish study and the Indian study.[3][4]
Compared with other options
Few studies compare scleral lenses directly with something else, and only one was randomized.
- Corneal rigid lenses, randomized crossover trial, UK. 34 people with keratoconus or similar conditions who already wore corneal rigid lenses successfully tried both lens types for several months each; 30 finished. Scleral lenses were rated significantly more comfortable. Vision, contrast sensitivity, and quality-of-life scores (NEI VFQ-25) were not significantly different. At the end, 53% preferred corneal lenses and 47% preferred scleral lenses, a difference that was not significant. People whose comfort in corneal lenses was already high tended to stay with them.[7]
- Ring segments and partial-thickness transplant, Brazil, retrospective, 55 eyes with advanced keratoconus. Eyes fitted with scleral lenses alone gained more corrected vision than eyes after ring segments. Many surgical eyes later needed a scleral lens anyway: 9 of 28 after a partial-thickness transplant (DALK) and 7 of 13 after ring segments. The sharpest final vision was in eyes that had DALK and then a scleral lens.[8]
For a plain-language comparison of the options, see scleral vs corneal rigid lenses and scleral lenses vs cross-linking, which treat different problems.
Avoiding or delaying a transplant
- Severe keratoconus, Belgium, retrospective. Of 75 eyes with very steep corneas, scleral lenses were prescribed for 51. After an average of about 30 months, 40 of those 51 were still wearing them. Eight of the original 75 eyes had transplant surgery.[10]
- After a hydrops episode, Belgium, retrospective. Hydrops is a sudden swelling when the cornea’s inner layer tears. Of 16 eyes, 11 (68.8%) were fitted successfully with mini-scleral lenses afterward. Three went on to transplant surgery.[11]
- Large US records study, 2,806 eyes. At a Michigan academic eye center, 22.7% of keratoconus eyes used scleral lenses and 3.2% of all eyes had a transplant during the study. After adjusting for other factors, scleral lens use was linked to a lower risk of transplant than no contact lens use (hazard ratio 0.19), and corneal rigid lens use was too (0.30).[9] This shows an association, not proof that the lenses prevented surgery: people who manage lenses well may differ in other ways.
Comfort and quality of life
- Satisfaction survey, US, 24 experienced wearers. Most had worn corneal rigid lenses before. A large majority strongly preferred the comfort and vision of their scleral lenses, and they reported less dryness. Slightly more than half had at least occasional midday fogging.[14]
- Turkey, 29 eyes. On a 5-point scale, average ratings were 4.69 for comfort and 4.62 for vision, and overall satisfaction averaged 88.1 out of 100.[3]
- France, prospective, 41 eyes of 24 people. After three months, the NEI VFQ-25 score rose by 19.5 points on average.[13]
- Belgium, prospective, 50 people. Among those still wearing the lenses at six months, visual functioning and social and emotional scores on the NEI VFQ improved significantly.[12]
- India, prospective, 14 people. After three months, the overall NEI VFQ-25 score and the subscales for distance and near activities, mental health, social functioning, and driving improved significantly.[4]
These questionnaires, and their limits, are explained on the quality-of-life research page.
Who keeps wearing them
- In the Belgian prospective study, 11 of 50 people (22%) stopped within six months, 7 of them because of handling. Of the 39 still wearing them, 33 (84.6%) averaged 12 hours a day.[12]
- In the 2010 US study, 12 of 32 people decided not to pursue scleral lenses after the first evaluation. Those fitted needed an average of 2.8 visits and 1.5 lenses per eye.[2]
- In the severe-keratoconus study, 4 of 51 eyes stopped because the person couldn’t handle the lenses, and 7 were lost to follow-up.[10]
The broader evidence on dropout, across conditions, is on the outcomes research page.
Safety
The most detailed safety snapshot in keratoconus is the US study of 157 eyes that had worn scleral lenses for at least a year:[1]
| Event | Share of eyes[1] |
|---|---|
| Any physiological adverse event | 9.6% |
| Hydrops (part of keratoconus itself) | 3.2% |
| Microbial keratitis (corneal infection) | 0.6% |
| Any lens-related event | 55.4% |
| Broken lens | 26.1% |
| Reservoir fogging | 7.0% |
| Lost some scleral lens vision, all from keratoconus progression | 14.6% |
The full breakdown is on the complications research page. The systematic review found handling problems reported in 10.4% to 63% of patients across studies and fogging in 58% in one, with physiological events reported only occasionally.[6]
The 14.6% figure matters: a scleral lens corrects vision but does not stop keratoconus from progressing.[1] Monitoring for progression, and cross-linking where it’s indicated, is a separate decision for you and your cornea specialist.
For what the condition is and how a scleral lens helps, see the keratoconus condition page.
Common questions
How much do scleral lenses improve vision in keratoconus?
In most studies, a lot. In a US study of 157 eyes, average acuity went from 0.50 logMAR in glasses to 0.08 with scleral lenses, on a scale where lower is better and 0.0 equals 20/20. How much you gain depends on how irregular your cornea is and what else is going on in the eye, so ask your fitter what is realistic for you.
Are scleral lenses better than corneal rigid lenses for keratoconus?
Not for everyone. In the only randomized trial we found, 30 people who already wore corneal rigid lenses successfully tried both. Scleral lenses were rated more comfortable, but vision and quality-of-life scores were similar, and about half chose each type at the end.
Do scleral lenses stop keratoconus from getting worse?
No study here shows that. Scleral lenses correct vision; they are not a treatment for progression. In the 157-eye study, 14.6% of eyes lost some scleral lens vision over time, all because the keratoconus progressed. Cross-linking is the treatment aimed at slowing progression.
Can scleral lenses help me avoid a corneal transplant?
For many people with advanced keratoconus, studies suggest yes. In one Belgian clinic, 40 of 51 eyes with severe keratoconus were still wearing scleral lenses after about two and a half years. A large US records study linked scleral lens use to a lower transplant rate, but that kind of study can't prove the lenses were the cause.
Why do people with keratoconus stop wearing scleral lenses?
Handling is the most common reason in the studies here. In a prospective Belgian study, 7 of the 11 people who stopped within six months did so because of difficulty putting the lenses in and taking them out.