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  • Cornea/External Disease, Refractive Mgmt/Intervention

    This is the first systematic review and meta-analysis of the natural history of keratoconus.

    Study design

    The authors performed a systematic review of data from 41 prospective and retrospective studies, and a meta-analysis of data from 23 of these studies. The studies assessed visual acuity, refraction and corneal curvature data from adult and pediatric patients. In all, the studies encompassed 11,529 eyes with keratoconus.


    The analysis revealed greater steepening of Kmax at 12 months in younger patients and those who presented with a 55 D or higher Kmax compared with other patients. For every 10-year increase in age, patients were predicted to experience 0.8 D less Kmax steepening over 12 months (P=0.01). In addition, for every 5 D increase in baseline Kmax, patients were predicted to have 1 D greater Kmax steepening (P=0.003). At 12 months, there was a significant increase in the average Kmean of 0.4 D (P=0.004).


    The authors analyzed data at 12 months, which is a short follow-up period in the context of a chronic disease such as keratoconus.

    Clinical significance

    Younger patients progress more aggressively and should be followed more closely and treated earlier. In particular, these findings suggest a need for closer follow-up and a lower threshold for cross-linking in patients younger than 17 years and in those with a Kmax steeper than 55 D.