JAN 30, 2024
Pediatric Ophth/Strabismus
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.