How to read this research
Before the numbers, a word on where they come from. Almost all scleral lens research falls into three types:
- Retrospective chart reviews. Researchers look back through records at one clinic. These are common and useful, but they only capture what was written down, and they can’t show cause and effect.
- Prospective cohort studies. Researchers enroll people and follow them forward. Better, but usually small and from one clinic.
- Surveys. Of fitters or of patients. Good for patterns, but they depend on who chooses to respond.
There are almost no randomized trials comparing scleral lenses with other lenses or with surgery. Some studies also include only people who were fitted successfully, which makes outcomes look better than they would for everyone who tries. We point this out where it applies.
Vision
Every study below found a significant improvement in vision with scleral lenses.
- Keratoconus, US clinic, retrospective, 157 eyes. Average best-corrected acuity on the logMAR scale (where lower is better and 0.0 equals 20/20) improved from 0.50 in glasses to 0.08 in scleral lenses. This study included only eyes successfully wearing lenses for at least a year. Over the study period, 14.6% of eyes lost some of their best scleral lens vision, all because their keratoconus progressed.[3]
- Irregular corneas from several causes, Israeli clinic, retrospective, 155 eyes of 97 people. Everyone had failed other forms of correction. Best vision with scleral lenses was significantly better than before, and similar across keratoconus, transplant, and other diagnoses.[6]
- After full-thickness corneal transplant, retrospective, 31 patients. Of the 28 people still wearing lenses, 82% reached functional vision (0.5 or better on the decimal scale).[7]
- PROSE devices at a US academic center, retrospective, 825 eyes. Vision improved by 0.46 logMAR on average in irregular corneas and by 0.20 logMAR in ocular surface disease.[9]
- Ocular surface disease, US tertiary center, retrospective with a patient survey. Of 212 people evaluated, 115 completed fitting. Average acuity improved from 0.32 logMAR with their usual correction to 0.12 logMAR with scleral lenses.[8]
The gains are largest where the cornea is most irregular, because that’s the problem a scleral lens solves and glasses can’t.
Quality of life and satisfaction
- Mini-scleral lenses in keratoconus, Belgium, prospective, 89 eyes of 50 people. Among those still wearing lenses, scores on a standard vision-related quality-of-life questionnaire (the NEI-VFQ) improved significantly for both visual functioning and social and emotional wellbeing.[4]
- Keratoconus, France, prospective, 41 eyes of 24 people. After three months of wear, the NEI-VFQ 25 score rose by 19.5 points on average.[11]
- Patient survey through the National Keratoconus Foundation. Comparing 76 people wearing scleral lenses in both eyes with 75 wearing corneal rigid lenses, scleral wearers rated vision (3.2 vs 2.6 out of 5) and comfort (3.3 vs 2.2) higher. Ease of use was rated about the same. Scleral wearers more often reported halos (72% vs 53%) and handling difficulty (63% vs 40%).[12]
Who keeps wearing them
This is where results vary most, because definitions of success, follow-up time, and patient groups differ.
| Study | Who | Design | Stopped wearing[1][2][4][6] | Main reason |
|---|---|---|---|---|
| Portugal, 2020 | 95 new wearers, mixed corneas | Prospective, 12 months | 27% | Handling (35% of those who stopped), then discomfort (19%) |
| US veterans, 2020 | 120 veterans, mean age 56.7 | Retrospective | 34.2% (median 5.2 months after fitting) | Insertion and removal (53.7% of those who stopped) |
| Belgium, 2021 | 50 people with keratoconus | Prospective, 6 months | 22% | Handling (7 of the 11 who stopped) |
| Israel, 2013 | 97 people, irregular astigmatism | Retrospective, mean 35 months | 27% | Not reported in the abstract |
Sources: Portugal[1], US veterans[2], Belgium[4], Israel[6].
A few patterns stand out:
- Irregular corneas do better. In the Portuguese study, 77% of people with irregular corneas completed the year, compared with 58% of those with regular corneas. None of the people who stopped did so because of an adverse event.[1]
- Handling gets easier with time. In the same study, the number of attempts needed to insert and remove the lenses fell significantly over the year, and average daily wear in new wearers rose from 9.8 to 11.1 hours.[1]
- Other health problems matter. Among the veterans, a neurological condition was linked to a higher chance of stopping (odds ratio 4.6).[2]
- Breaks may help. In the Israeli study, people who took brief breaks to refill their lenses every 4 to 5 hours of wear had a significantly higher success rate.[6]
- Wear time among those who continue can be long. In the Belgian study, 33 of the 39 people still wearing lenses (84.6%) wore them for an average of 12 hours a day.[4]
Avoiding or delaying a transplant
- Severe keratoconus, Belgium, retrospective. At a university keratoconus clinic, scleral lenses were proposed for 75 eyes with very steep corneas and were prescribed for 51. After an average of about 30 months, 40 of those 51 eyes were still wearing them. Four had stopped because they couldn’t handle the lenses, and seven were lost to follow-up. Eight of the original 75 eyes went on to transplant surgery. The authors concluded that the need for transplants in their keratoconus population was more than halved.[5]
- Advanced ectasia, US, retrospective comparison. Among 36 people evaluated for PROSE and 37 who had a transplant, all PROSE eyes were fitted successfully, and vision was reached faster and was better on average than after transplant. The transplant group had more severe disease, which makes a fair comparison difficult.[10]
Ocular surface disease
For severe dry eye and other surface disease, the goal is often comfort and protection rather than sharper vision alone. In the US tertiary-center series, therapeutic goals such as better comfort, surface protection, or healing were reached in all but 2 of the 115 people who completed fitting. They had tried an average of 3.2 other treatments first.[8]
Treatment doesn’t work for everyone. At one PROSE center, 8 of 125 eyes (6.4%) failed treatment, most often because of corneal swelling in eyes with a weakened inner corneal layer. Eyes with Fuchs’ dystrophy or a previous full-thickness transplant failed more often (22.2%) than other eyes (1.6%).[13]
For the downside of the picture, see what the research shows on complications. For a sense of what wearing the lenses takes day to day, see the wearing guides and the worry page on whether scleral lenses are hard to put in.
Common questions
What is the success rate of scleral lenses?
It depends on who is studied and how success is defined. In a one-year prospective study of 95 wearers, 73% were still wearing their lenses at 12 months. In a study of 120 veterans, 34.2% had stopped, and in a mini-scleral study of 50 people with keratoconus, 22% had stopped by six months.
Why do people stop wearing scleral lenses?
Across studies, the most common reason is difficulty putting the lenses in and taking them out. Discomfort is the next most common in some studies. In the one-year prospective study, none of the people who stopped did so because of an adverse event.
Do scleral lenses work better for some conditions than others?
In the one-year prospective study, 77% of people with irregular corneas kept wearing their lenses, compared with 58% of people with regular corneas. People with irregular corneas usually gain more vision, which may make the effort feel more worthwhile.
Can scleral lenses help me avoid a corneal transplant?
For some people with keratoconus, yes. In one Belgian clinic, 40 of 51 eyes with severe keratoconus that would otherwise have been referred for transplant were still wearing scleral lenses after about two and a half years. Whether that applies to you is a question for your cornea specialist and fitter.
Is the research on scleral lenses high quality?
It's growing, but most studies are retrospective chart reviews or prospective studies from a single clinic, with no comparison group. They consistently point the same way on vision, which is reassuring, but exact percentages vary widely.