Scleral lenses for keratoconus: clear, comfortable vision when glasses stop working

One of the hardest moments in keratoconus is when glasses simply stop giving clear vision, no matter how often the prescription is changed. It is not that the right lens has not been found; a smooth lens cannot correct an irregular cornea. This is the point where scleral lenses make a real difference for many people, and two recent studies put numbers on how much.

Why glasses reach their limit

Glasses and ordinary soft contact lenses assume a reasonably regular corneal shape. In keratoconus the cornea is cone-shaped and uneven, so light scatters rather than focusing to a point. Vision through glasses can stay blurred, ghosted or streaked even with a “perfect” prescription. Correcting the irregular surface itself is the way through, and that is what specialty contact lenses do.

How scleral lenses work

A scleral lens is a larger rigid lens that does not rest on the cornea at all. It vaults over the cornea and lands gently on the white of the eye (the sclera), which is far less sensitive. The gap beneath fills with sterile saline, replacing your irregular corneal surface with a smooth optical one. In the Hadimani study described below, lenses were fitted with a fluid gap of 250 to 350 microns on insertion, settling to at least 150 microns, so the lens never presses on the fragile cone. The fluid bath also helps dry, sensitive eyes.

What the research shows

Vision. Hadimani and colleagues (2024) fitted 16.0 mm scleral lenses to both eyes of 14 people (28 eyes; average age 29) with keratoconus who could not see adequately with glasses or corneal rigid lenses, and followed them for three months. Best glasses-corrected vision averaged 0.47 logMAR (roughly 6/18) and improved to 0.03 logMAR (roughly 6/6) with scleral lenses, about four lines on the chart (P < 0.001). Every eye reached 6/12 or better. Low-contrast vision, reading faint grey letters, also improved, from 0.68 to 0.47 logMAR (P < 0.001). A P-value below 0.001 means a difference this large would appear by chance less than once in 1,000 times.

Kreps and colleagues (2021) ran a prospective study at two university contact lens clinics in Belgium. Of 68 people fitted, 18 were excluded (mostly for age under 18 or previous corneal surgery), leaving 50 adults and 89 eyes, median age 38; none had worn sclerals before. Lenses were mini-sclerals of 16.0 to 17.0 mm across three designs, and it took an average of 1.1 lenses per eye to reach a final fit. Median vision improved from 0.22 logMAR (range 0.02 to 1.04) to 0 logMAR, the equivalent of 6/6 (P < 0.0001). Put more plainly: before fitting, 31.5% of eyes saw 0.1 logMAR (about 6/7.5) or better; with the lenses, 83.1% did, and the 39.3% of eyes seeing worse than 0.4 logMAR beforehand fell to none.

Quality of life. Both studies used the NEI VFQ, a validated questionnaire about how vision affects daily life. In the Hadimani study (VFQ-25) the overall score rose from a median of 1,735 to 2,930 after three months (P = 0.001), with large gains in distance and near activities, vision-related mental health and driving. Colour vision, as expected, did not change. Kreps and colleagues used the longer VFQ-39 and found that, among the 39 people still wearing lenses at six months, visual functioning, socio-emotional wellbeing, distance and near activities all improved (P < 0.0001).

Wearing time and comfort. Hadimani’s participants wore their lenses an average of 9.5 hours a day (range 8 to 16) and rated comfort 7.5 out of 10. In the Kreps study, 33 of the 39 people still wearing lenses at six months (84.6%) wore them around 12 hours a day, the limit the clinics advised; the other six wore them 7 to 10 hours. Midday fogging of the fluid under the lens affected 11 people (28.2%), mostly managed with artificial tears, and five (12.8%) wore lenses only on workdays because handling took too long.

The honest part: not everyone keeps going

In the Kreps study, 11 of 50 patients (22%) had stopped wearing their mini-scleral lenses by six months: seven because of difficulty inserting and removing the lenses, three because of discomfort and one because of dissatisfaction with vision. People fitted in one eye only were more likely to stop than those fitted in both (36.4% versus 17.9%), though with such small numbers that could be chance (P = 0.229). Age, corneal steepness, starting vision and vision gained did not predict who stopped. Handling is a learned skill, and a fitting clinic that spends time teaching it and follows up in the first weeks is what separates giving up from years of clear vision.

On safety, Kreps and colleagues reported no infectious keratitis or serious complications over six months; one person stopped after repeated small peripheral corneal infiltrates that healed without lasting harm. Side effects in the Hadimani study were minor (redness, itching, tearing, light sensitivity, haloes) and none were serious over three months, though frequencies were not reported.

What the studies can’t tell us

Both are small. Hadimani’s study followed 14 people for only three months at a single centre in India, used one lens design, had no comparison group and no masking, and its authors say larger, longer studies are needed to confirm the results. Its quality-of-life figures are raw summed scores, so cannot be compared directly with other papers. Kreps and colleagues list their own limits: six months of follow-up, no children, no adjustment for education or socioeconomic factors, a general rather than keratoconus-specific questionnaire, only high-contrast vision measured, no comparison with corneal rigid lenses, and quality-of-life results only from people who kept wearing the lenses. Neither study tells us how scleral lenses perform over years or after cross-linking.

Scleral lenses and cross-linking work together

Think of keratoconus care as two jobs. Corneal cross-linking, performed by an ophthalmologist, aims to reduce the chance of the cornea progressing. Scleral lenses restore vision on the shape you have. One protects the future; the other gives you back today. Many people benefit from both, and the same keratoconus-focused optometrist who fits your lenses is the person who maps your cornea over time and refers you for cross-linking if progression is documented.

Being fitted in New Zealand

Rose Optometry in Hamilton, the home of the Rose K lens, runs a dedicated keratoconus and specialty contact lens clinic and, with the New Zealand Eye Research Centre, fits patients and accepts referrals from across the country. You do not need a GP referral to see an optometrist.

If glasses are no longer giving you the vision you need, scleral lenses are often the next step worth exploring. You can book a keratoconus and lens assessment to find out what your eyes are capable of.

This article is general information and not a substitute for a clinical assessment. Whether scleral lenses suit you depends on an examination of your own eyes.

References

Sourced and verified via PubMed.

• Kreps EO, Pesudovs K, Claerhout I, Koppen C. Mini-Scleral Lenses Improve Vision-Related Quality of Life in Keratoconus. Cornea. 2021;40(7):859-864. PMID 32947413. doi:10.1097/ICO.0000000000002518
• Hadimani SR, Kaur H, Shinde AJ, Chottopadhyay T. Quality of life and vision assessment with scleral lenses in keratoconus. Saudi Journal of Ophthalmology. 2024;38(2):173-178. PMID 38988786. doi:10.4103/sjopt.sjopt_157_23