Localising rectus muscle insertions using high frequency wide-field ultrasound biomicroscopy.
OBJECTIVE
The ultrasound biomicroscope (UBM) can accurately locate an extraocular muscle (EOM) insertion. The authors compared the accuracy of the Sonomed UBM (SUBM), a new 'wide-field ultrasound biomicroscope', with the older model Humphrey UBM (HUBM) in localising EOM insertions and compared their ranges of detection of muscle insertions.


METHODS
Prospective, double-masked, observational study of 27 patients undergoing primary (n=40 muscles) or repeat (n=10 muscles) horizontal or vertical rectus muscle surgery. EOM insertional distances were measured with SUBM, and then intraoperatively with callipers. A Bland-Altman analysis and intraclass correlation coefficient were used to compare the SUBM and surgical data.


RESULTS
For all muscles, the differences between SUBM and surgery measurements were less than 1.0 mm. The mean of the SUBM insertion distances was 6.67 mm (SD 1.65 mm) versus 6.7 mm (SD 1.6 mm) at surgery. The intraclass correlation coefficient showed 'excellent' correlation between the two sets of data and was higher than that reported with HUBM. The image quality with the SUBM was superior to the HUBM, and its range of field was much larger (14×18 mm vs 5×6 mm).


CONCLUSIONS
The SUBM with its smaller, more manoeuvrable probe handpiece and a wider scanning field was more accurate in detecting muscle insertions compared with HUBM.
Department of Ophthalmology and Vision Sciences, Hospital for Sick Children, 555 University Avenue, Toronto, ON M5G 1X8, Canada.
Hayat Ahmad
HA
Khan
David R
DR
Smith
Stephen P
SP
Kraft
D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D033401:Microscopy, Acoustic; D009801:Oculomotor Muscles / Q000000981:diagnostic imaging* / Q000601:surgery; D013508:Ophthalmologic Surgical Procedures; D011446:Prospective Studies; D015203:Reproducibility of Results; D013285:Strabismus / Q000000981:diagnostic imaging* / Q000601:surgery; D015348:Vision, Binocular