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. Conventional scleral lenses mask around 60 to 65% of the higher-order optical distortions that glasses cannot touch. In the 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 the many people with keratoconus who have 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 there is less than a 1 in 1,000 chance a difference this large would appear if the lenses made no real difference.

Kreps and colleagues (2021) reported on 89 eyes of 50 keratoconus patients fitted with mini-scleral lenses: median vision improved from 0.22 logMAR (range 0.02 to 1.04) to a median of 0 logMAR, the equivalent of 6/6 (P < 0.0001).

Quality of life. Both studies used the NEI VFQ-25, a validated questionnaire about how vision affects daily life. In the Hadimani study the overall score rose from a median of 1,735 to 2,930 after three months (P = 0.001), with large gains in distance activities (137.5 to 287.5), near activities (175 to 300), vision-related mental health (137.5 to 300) and driving (125 to 250). Colour vision, as expected, did not change. Kreps and colleagues likewise found the visual functioning and socio-emotional scales 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 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, and 7 of those 11 gave up because of difficulty inserting and removing the lenses. That is worth knowing before you start: 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.

Side effects in the Hadimani study were minor: redness, itching, tearing, light sensitivity, haloes, burning, unusual discharge and occasional blur. None were serious over three months, though the paper does not report how often each occurred.

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 rather than the usual 0 to 100 scale, so they cannot be compared directly with other papers. For Kreps and colleagues, only the abstract was available to us, so we cannot report their fitting methods or the reasons the other four patients stopped. Neither study tells us how scleral lenses perform over years, in children, or after cross-linking, and neither compares them head-to-head with other lens types.

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

Scleral lens fitting is built on precise corneal imaging and patient, iterative adjustment. 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