Tailored cross-linking: what the pooled evidence shows, and where your optometrist fits in

Corneal cross-linking (CXL) is the main treatment used to slow keratoconus progression. In standard cross-linking, the ultraviolet light is spread evenly across the central cornea. "Customised" or tailored cross-linking takes a different approach: the light dose is shaped to each cornea, usually concentrating more energy over the cone where the cornea is weakest. A 2026 meta-analysis pooled the evidence on customised CXL. Here is what it found, what it cannot tell us, and where your optometrist fits into the journey.

Please note: this article is based on the published abstract of the review. We were not able to access the full paper, so we have used only the figures in the abstract.

What the researchers did

This was a systematic review and meta-analysis by a team from Chang Gung Memorial Hospital in Taiwan.

• Search: electronic databases up to 1 May 2025, yielding 394 records.
• Studies included: 19 in the review, with 14 suitable for meta-analysis.
• Duration: the main outcomes were changes at 12 months.
• Primary outcomes: change in maximum keratometry (Kmax, the steepest point of the cornea), corrected distance visual acuity (CDVA, the sharpest vision achievable with glasses or lenses) and thinnest corneal thickness (TCT).
• Comparator: the authors did two kinds of analysis: single-arm results for customised CXL alone, and comparisons against non-customised (standard) CXL.
• Subgroups: epithelium-on versus epithelium-off treatment, and different irradiation patterns.

The abstract does not say how many of the included studies were randomised trials, how many were observational, or whether outcome assessors were masked. Without that, we cannot judge how strong the evidence is.

What they found

Within the customised CXL group

At 12 months, customised CXL reduced Kmax by -1.29 D (95% CI -1.55 to -1.03 D). A negative number here means the cornea became slightly flatter, rather than steeper.

CDVA improved by -0.10 logMAR (95% CI -0.12 to -0.07; P < .001). On the logMAR scale, a lower number means sharper vision, so a negative change is an improvement.

The thinnest point of the cornea decreased modestly, by -4.42 μm (95% CI -7.24 to -1.60 μm; P = .006). Total higher order aberrations (-0.24 μm; 95% CI -0.37 to -0.11 μm; P = .016) and vertical coma (-0.25 μm; 95% CI -0.49 to -0.00 μm; P = .049) also decreased. These are measures of the irregular optical blur typical of keratoconus.

Customised versus standard CXL

This is the between-group comparison, and it is the part most people want to know about:

• Kmax: customised CXL produced an additional -1.39 D of flattening compared with non-customised CXL (95% CI -1.82 to -0.95 D; P < .001).
• Vision: the improvement in CDVA was greater with customised CXL, with a mean difference of -0.06 logMAR (P = .031).

Outcomes were reported as comparable between epithelium-on and epithelium-off customised CXL. No significant endothelial cell loss or serious adverse events were reported.

Making sense of the statistics

A 95% confidence interval (CI) is a range of plausible values for the true effect. For the Kmax comparison, the whole range sits below zero, which suggests a real difference in favour of customised CXL in these studies. A P-value tells you how surprising the result would be if there were no true difference; smaller values mean chance is a less likely explanation. The vision difference (P = .031) is statistically significant, but -0.06 logMAR is a small difference and may not feel dramatic day to day.

The authors conclude that customised CXL is safe and effective and gives better topographic and visual outcomes than standard CXL. Given the limits below, we would describe it more cautiously: in the pooled studies, tailored cross-linking was associated with more corneal flattening and slightly better vision at 12 months, on average. Like all procedures, cross-linking carries risks, which should be discussed with the treating ophthalmologist.

Where your optometrist fits in

Cross-linking is performed by an ophthalmologist. But most people's keratoconus journey starts, and continues, with a keratoconus-focused optometrist, who:

• Diagnoses keratoconus, often early, using corneal tomography.
• Documents progression with sequential corneal maps, so any referral is based on genuine change rather than a single reading.
• Refers at the right time to an ophthalmologist to discuss whether cross-linking, standard or customised, is suitable. You can read more in our overview of corneal cross-linking in New Zealand.
• Looks after vision afterwards, including monitoring and fitting specialty or scleral lenses once the cornea has settled. See our guide to follow-up, vision and contact lenses after cross-linking.

For people with thinner corneas, tailored protocols have been studied too, which we discussed in our article on thin-cornea cross-linking and five-year results. At Rose Optometry in Hamilton, our optometrists, including Jagrut Lallu and Jacqueline Rowe, provide this monitoring, referral and lens-fitting care.

What the studies can't tell us

• Abstract only. We have not seen the full paper, so we cannot check study quality, how much studies disagreed, or the sample sizes.
• Study design unclear. The abstract does not say whether studies were randomised or masked. Non-randomised comparisons can be affected by differences between patient groups.
• Short follow-up. The main results are at 12 months. Longer-term stability is not addressed in the abstract.
• Different protocols. "Customised" covers several irradiation patterns and both epithelium-on and epithelium-off methods, which are not identical.
• Safety reporting. "No serious adverse events reported" is not the same as no risk, especially across a limited number of studies.

The take-home message

Tailored cross-linking looks promising in pooled 12-month data, with more flattening and slightly better vision than standard CXL on average, though the quality of the underlying studies cannot be judged from the abstract. Whichever approach is considered, it starts with careful documentation of progression. If you would like your keratoconus assessed and monitored, you can book a keratoconus assessment with our optometrists in Hamilton.

References

• Hsu JH, Tsai TH, Lin TW. Clinical Outcomes and Safety of Customized Corneal Cross-linking for Keratoconus: A Systematic Review and Meta-analysis. Journal of Refractive Surgery. 2026;42(5):e496-e507. PMID 42113928. https://doi.org/10.3928/1081597X-20260216-01