Keratometry has long been a cornerstone of contact lens fitting.

The British Contact Lens Association (BCLA) CLEAR report (2021-22), a major international evidence synthesis, challenges the long-held assumption that keratometry is essential for routine soft lens fitting in healthy eyes. As modern lenses are designed differently, the report points to a growing shift towards empirical fitting and on-eye assessment of performance.

As Keyur Patel FCOptom, optometrist from Tompkins Knight and Son Optometrists in Northampton, says, this shift is closely tied to how modern lenses are designed and distributed. “They’re designed to fit the majority of the population without needing to customise for individual corneal curvature. In that context, if you’re fitting that type of lens, you do start to question whether keratometry is adding anything meaningful to the process.” 

Traditional keratometry captures only part of a much more complex ocular surface. It primarily reflects the central approximate 3mm of the cornea but does not directly measure sagittal depth, limbal shape or scleral contour, all of which influence how a contact lens behaves on the eye (BCLA, 2021-22).

As Keyur points out, this limitation becomes more apparent in light of newer imaging technologies. “A keratometer is really only giving you a very small snapshot of the cornea, and that’s useful to a point, but we now know that lens fit is influenced by much more than that. With corneal topography, for example, you can map thousands of points across the surface and even begin to understand how the cornea transitions into the sclera.”