Echographic study of extraocular muscle thickness in children and adults.
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.
Saccà
S
S
Department of Neurological Sciences and Neurorehabilitation, Section of Ophthalmology, University of Genoa, Genoa, Italy. sacca@smartino.ge.it
Polizzi
A
A
Macrì
A
A
Patrone
G
G
Rolando
M
M
D000293:Adolescent; D000328:Adult; D000375:Aging / Q000473:pathology*; D000704:Analysis of Variance; D001699:Biometry / Q000379:methods; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D008297:Male; D024510:Muscle Development; D009801:Oculomotor Muscles / Q000033:anatomy & histology / Q000000981:diagnostic imaging* / Q000254:growth & development; D012016:Reference Values; D015203:Reproducibility of Results; D014463:Ultrasonography