S Saccà1, A Polizzi, A Macrì, G Patrone, M Rolando. 1. Department of Neurological Sciences and Neurorehabilitation, Section of Ophthalmology, University of Genoa, Genoa, Italy. sacca@smartino.ge.it
Abstract
BACKGROUND: Echobiometric evaluation of extraocular muscles in normal subjects has been performed previously, but only in adults. We determined extraocular muscle thickness in normal subjects in three age groups. METHODS: Extraocular muscle thickness was studied in 75 normal subjects divided into three age groups (5-10, 11-15 and 28-37 years) using a Biovision B-scan-S instrument in standardized A-mode (frequency, 10 MHz; biometry resolution, 0.15 mm; depth, 40-60 mm; points on X axis, 512; levels on Y axis, 256). All measurements were performed by the same operator and repeated five times. The reproducibility of the technique was determined using the coefficient of variation. The one-way ANOVA test was used to compare the three groups, and the two-tailed unpaired t-test was used to compare subjects aged 5-10 years and those aged 11-15 years, and subjects aged 11-15 years with those aged 28-37 years. RESULTS: The technique showed good reproducibility. In subjects 5-10 years old, the coefficient of variation was 8%; in subjects 11-15 years and 28-37 years old, it was 5%. Increased muscle thickness was observed with age (p < 0.001). A statistically significant difference between the medial and inferior recti muscles in subjects 11-15 years and 28-37 years old was found (p < 0.001). CONCLUSIONS: The increased thickness of all recti muscles may be influenced by growth (primarily during puberty), and the variations in thickness of the extraocular muscles may be attributable to near-vision stimulus of the inferior and medial recti muscles.
BACKGROUND: Echobiometric evaluation of extraocular muscles in normal subjects has been performed previously, but only in adults. We determined extraocular muscle thickness in normal subjects in three age groups. METHODS: Extraocular muscle thickness was studied in 75 normal subjects divided into three age groups (5-10, 11-15 and 28-37 years) using a Biovision B-scan-S instrument in standardized A-mode (frequency, 10 MHz; biometry resolution, 0.15 mm; depth, 40-60 mm; points on X axis, 512; levels on Y axis, 256). All measurements were performed by the same operator and repeated five times. The reproducibility of the technique was determined using the coefficient of variation. The one-way ANOVA test was used to compare the three groups, and the two-tailed unpaired t-test was used to compare subjects aged 5-10 years and those aged 11-15 years, and subjects aged 11-15 years with those aged 28-37 years. RESULTS: The technique showed good reproducibility. In subjects 5-10 years old, the coefficient of variation was 8%; in subjects 11-15 years and 28-37 years old, it was 5%. Increased muscle thickness was observed with age (p < 0.001). A statistically significant difference between the medial and inferior recti muscles in subjects 11-15 years and 28-37 years old was found (p < 0.001). CONCLUSIONS: The increased thickness of all recti muscles may be influenced by growth (primarily during puberty), and the variations in thickness of the extraocular muscles may be attributable to near-vision stimulus of the inferior and medial recti muscles.