Correlation of optic nerve sheath diameter with height, weight, body mass index and age

ABSTRACT

Abstract The study was conducted to determine the relationship or association between optic nerve sheath diameter and age, weight, sex, height, and Body mass index (BMI) in children of the South West Nigeria extraction. A cross-sectional study was carried out among 2-14-year-old children of the selected school in a suburban town in Southwest Nigeria. Approval was obtained from the institutional Human Research Ethics Research Committee, and consent was obtained from parents of the children. Where indicated, assent was obtained from the children. A pediatric ophthalmologist ascertained the normalcy of the eyes with visual acuity, refraction and fundoscopy. Height and weight were measured according to standard protocol and BMI was calculated from weight and height. The scanning was done by a radiologist with 4-12MHz Linear transducer on a gently closed upper eyelid with a B-mode ultrasound machine (Clear Vue 550 Phillips Model). No sedation was involved. The mean ONSD for the right eye was 0.54±0.07cm (5.4mm), while the left eye was 0.56±0.07cm (5.6mm). The optic nerve sheath diameter was longer in the left eye for all subjects, and this may be due to the fact that females have shorter diameter in the right eyes. ONSD did not correlate with height, weight and BMI. The mean ONSD is affected by sex in the right eye. This may be indicative of a relatively lower intraocular pressure in the right eyes of the girls. Therefore, in the use of the optic nerve sheath diameter as surrogate for intraocular pressure, it is preferable to use the left eye in which there is no sex difference