Prevalence and Associations of Keratoconus Among Children, Adults, and Elderly in the Population-Based Ural Eye Studies.

Abstract

To estimate prevalence and associations of keratoconus in populations in Russia with an age from childhood to seniority. The study population consisted of the cohorts of 3 population-based studies performed in urban and rural areas within the same geographical region in Bashkortostan/Russia: the Ural Children Eye Study (UCES; age = 6-18 y; n = 4890), the Ural Eye and Medical Study (UEMS; age = >40 y; n = 5314), and the Ural Very Old Study (UVOS; age = >85 y; n = 651). Based on Scheimflug imaging, keratoconus was defined by a keratometric reading of ≥48 diopters (D) in any eye. The mean maximal and minimal corneal refractive power increased from the UCES (43.58 ± 1.50 D and 42.70 ± 1.42 D, respectively) to the UEMS (44.26 ± 1.70 D and 43.61 ± 1.76 D, respectively) and to the UVOS (45.1 ± 1.72 D and 43.98 ± 1.68 D, respectively). Correspondingly, keratoconus prevalence increased from the UCES (42/4890; 0.086%; 95% CI = 0.060, 0.112) to the UEMS (112/5314; 2.11%; 95% CI = 1.72, 2.49) and to the UVOS (42/651; 6.45%; 95% CI = 4.56, 8.34). In the UCES, higher keratoconus prevalence was associated (multivariable analysis) with higher birth order [odds ratio (OR) = 2.34; 95% CI = 1.32, 4.15; P = 0.004], lower birth weight (OR = 0.99; 95% CI = 0.99, 0.99; P < 0.001), and shorter axial length (OR = 0.15; 95% CI = 0.08, 0.30; P < 0.001). In the UEMS, keratoconus prevalence correlated with shorter axial length (OR = 0.15; 95% CI = 0.10, 0.23; P < 0.001), larger corneal volume (OR = 1.17; 95% CI = 1.09, 1.25; P = 0.001), thicker lens (OR = 2.27; 95% CI = 1.06, 5.28; P = 0.04), cortical cataract degree (OR = 1.02; 95% CI = 1.01, 1.04; P = 0.01), and higher stage of age-related macular degeneration (OR = 1.65; 95% CI = 1.09, 2.51; P = 0.02). In the UVOS, keratoconus prevalence correlated with lower educational level (OR = 0.84; 95% CI = 0.71, 0.99; P = 0.04) and lower dynamometric handgrip force (OR = 0.92; 95% CI = 0.88, 0.97; P = 0.003). In this study on multiethnic groups from Russia, keratoconus prevalence increased from the pediatric group (0.09%) to the adult group (2.11%) and seniority group (6.45%), correlated mostly with biometric ocular parameters and was in all age groups statistically independent of most systemic parameters.