Distribution of Refractive, Anterior Corneal and Ocular Residual Astigmatism in Children with Idiopathic Congenital Nystagmus - A Cross-Sectional study

Background Idiopathic nystagmus is a developmental oculomotor dysfunction. Individuals with ICN showed a higher rate of astigmatism compared to typically developing children. The aim of the study was to determine the distributions of refractive, corneal, and ocular residual astigmatism in children with idiopathic congenital nystagmus (ICN). Methods Refractive astigmatism (RA) was obtained from objective cycloplegic refraction. Anterior corneal astigmatism (ACA)was determined by a hand-held keratometer. Thibos vector analysis was used to calculate ocular residual astigmatism(ORA). All the patients were divided into the following groups: preschool (2–4 years), school-age (5–12 years) and adolescents (13–18 years) years. Results A total of 218 patients, 149 (68.3%), were male, and 69 (31.7%) were female. The mean ± SD age of patients was 7.29 ± 3.96 years (range 2–18years). The overall prevalence and median value of (RA) was 156 (71.6%) CI (65–78), 1D that of ACA was 166 (76.1%) CI (70–81), 1.5D and that of ORA was 136 (62.4%) CI (56–68),1D respectively. In terms of magnitude, the prevalence of RA was moderate 81 (37.2% ), that of ACA was low 74 (33.9%), and that of ORA was negligible 82 (37.6%). WTR is highly prevalent in RA 110 (50.5%) and ACA 58 (66.1%) whereas ATR 107 (49.1%) is commonly observed among ORA. There was a statistically significant change in axis with age (p < 0.001) but there was a moderate positive correlation between the magnitude of the RA and the ACA (r = 0.416, p = 0.01). Conclusion Children with idiopathic congenital nystagmus had high prevalence of astigmatism involving refractive, anterior corneal and ocular residual astigmatism. WTR astigmatism was predominately presented on refractive and corneal astigmatism whereas ATR was predominance in ORA. So, comprehensive assessment including ACA and ORA is important to accurately diagnose the astigmatic profile and optimize long term clinical management in children with Idiopathic congenital nystagmus.