Tomographic and Refractive Characteristics of Pediatric First-Degree Relatives of Keratoconus Patients

Purpose To evaluate the tomographic and refractive characteristics of pediatric first-degree relatives of patients with keratoconus. Design Cross-sectional study. Methods Setting : Department of Ophthalmology at the American University of Beirut Medical, Beirut, Lebanon. Study Population : Pediatric first-degree relatives of patients with keratoconus. Both eyes of all participants aged between 6 and 18 years were included and studied. Exclusion Criteria : Soft contact lens use in the past 2 weeks or rigid gas-permeable lens wear within 4 weeks, history of prior ocular surgery or infectious keratitis, and unreliable corneal tomography. Masking and Randomization : Two masked cornea and refractive surgeons of different training backgrounds independently evaluated the participants' tomographic outputs. Additionally, the tomographic data were analyzed using Smadja's decision tree. Observation Procedures : Scheimpflug tomography, manifest refraction, and slit-lamp examination. Main Outcome Measures : Anterior curvature indices, posterior elevation values, thinnest pachymetry, and subjective and objective tomographic interpretation. Results One hundred eighty-three subjects were recruited. Tomographic evaluation after Cohen's kappa coefficient analysis revealed 32 patients as having keratoconus (17.5%), while 35 patients (19.1%) were labeled as keratoconus by objective analysis. There were 11.5%-15.5% of patients with keratoconus aged less than 11 years, 18.0% aged 12-15 years, and 25.5% aged 16-18 years. Their respective steepest anterior curvature and thinnest pachymetry are 44.8 ± 6.5 diopters (D) and 515.9 ± 39.2 μm, 47.34 ± 3.4 D and 496.1 ± 37.9 μm, and 49.7 ± 6.1 D and 486.0 ± 66.5 μm. A total of 37.5% of the keratoconus patients were unilateral as evaluated by tomography alone. Conclusions The prevalence of keratoconus in pediatric first-degree relatives of diagnosed keratoconus patients is high. Screening in this high-risk group is warranted.