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  • Most Children With Stable High Regular Astigmatism Do Not Develop Keratoconus

    Pediatric Ophth/Strabismus

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    Review of: Children with high astigmatism: Tomographic and refractive characteristics and the ability of current indices to rule out keratoconus

    Fattah M, Mireskandari K, Fung S, et al. Journal of American Association for Pediatric Ophthalmology and Strabismus, December 2023

    Certain topographic and tomographic features in children with high astigmatism remain stable over time, meaning these features can be used to rule out keratoconus.

    Study Design

    This longitudinal observational study retrospectively analyzed the corneal tomographic, topographic, and refractive changes in 67 children (mean age 9.1 years) with regular cylindrical refraction ≥3.50 D referred to the Hospital for Sick Children in Toronto between January 2009 and June 2020 for evaluation of possible keratoconus. Examinations were conducted every 4–6 months.

    Outcomes

    At the last follow-up visit, no eyes were found to have developed keratoconus, with the only significant change being a spherical refraction shift from −2.62 to −3.16 D. The maximum inferior–superior dioptric asymmetry (I-S) ratio absolute value was maintained at <1.6 throughout the study period, and the average keratometry, inferior–superior, and astigmatism index (KISA%) value only increased from 3.14 to 3.21. Both values indicated normal eyes at both the baseline and last follow-up visits.

    Limitations

    Due to its strict exclusion criteria and its retrospective nature, the study population was small, and the follow-up period varied from 6 months to 7.7 years. It is also possible that the study overestimated the specificity of the Pentacam indices in ruling out subclinical and clinical keratoconus.

    Clinical Significance

    More children with astigmatism are being referred for evaluation of keratoconus. Little has been known about the natural history of high astigmatism in children, and the results from this study help elucidate the topographic and tomographic features that are most useful in ruling out subclinical or manifest keratoconus in these patients, particularly the I-S ratio (<1.6) and KISA%. Being able to distinguish between children with high regular astigmatism and children with early keratoconus is also helpful to determine appropriate follow-up intervals.

    Financial Disclosures: Dr. Phoebe Lenhart discloses no financial relationships.