Evaluation of ciliary sulcus diameter using ultrasound biomicroscopy in emmetropic eyes and myopic eyes.

PURPOSE

To measure the ciliary sulcus-to-sulcus (STS) diameter in 4 axes in emmetropic and myopic eyes using ultrasound biomicroscopy (UBM) and compare the measurements with automated horizontal white-to-white (WTW) diameter measurements.

SETTING

University Eye Hospital Freiburg, Freiburg im Breisgau, Germany.

DESIGN

Evaluation of diagnostic technology.

METHODS

The STS diameter was measured at 0, 45, 90, and 135 degrees using 35 MHz UBM. The 0-degree WTW diameters were obtained using scanning-slit topography (Orbscan) and partial coherence interferometry (PCI) biometry (IOLMaster). The 0-degree STS and 90-degree STS were compared using the paired t test; the Pearson correlation was used to assess whether the 0-degree STS diameter could be predicted from the 0-degree WTW diameter.

RESULTS

The mean SE refraction was -0.48 diopter (D) ± 0.35 (SD) in emmetropic eyes and -9.55 ± 3.70 D in myopic eyes. In 35 of 37 eyes, 90-degree STS was greater than 0-degree STS. The mean 90-degree STS was 12.51 ± 0.43 mm. The mean 0-degree STS was 12.19 ± 0.47 mm (P<.01). The mean 0-degree WTW diameters were 11.73 ± 0.37 mm (scanning-slit topography) and 12.20 ± 0.42 mm (PCI biometry). The correlations were good between 0-degree STS and 0-degree WTW with PCI biometry (r(2) = 0.82) and scanning-slit topography (r(2) = 0.86) in emmetropic eyes but weak between 0-degree STS and 0-degree WTW in myopic eyes (r(2) = 0.36 and r(2) = 0.40, respectively).

CONCLUSIONS

Sulcus diameter measurements were most precise using UBM. The ciliary sulcus is vertically oval. The WTW diameter is not suitable for calculating a PC pIOL diameter, particularly in myopic eyes.