Ultrasound biomicroscopy more precise for measuring sulcus diameter

J Cataract Refract Surg. 2011;37(9):1686-1693

Sulcus diameter measurements using ultrasound biomicroscopy were found to be more precise than those obtained via automated horizontal white-to-white diameter measurement, according to a study.

"The ciliary sulcus is vertically oval. The [white-to-white] diameter is not suitable for calculating a [posterior chamber phakic IOL] diameter, particularly in myopic eyes," the study authors wrote.

The researchers evaluated the diagnostic technology by measuring the ciliary sulcus-to-sulcus diameter in four axes (0°, 45°, 90°, and 135°) in emmetropic and myopic eyes using 35 MHz ultrasound biomicroscopy. Measurement results were then compared with automated horizontal 0° white-to-white diameter measurements obtained using Orbscan scanning-slit topography (Bausch + Lomb) and IOLMaster partial coherence interferometry biometry (Carl Zeiss Meditec).

Pearson correlation was used to assess whether the 0° sulcus-to-sulcus diameter could be predicted from the 0° white-to-white diameter.

Results showed that the mean spherical equivalent refraction was -0.48 D in emmetropic eyes and -9.55 D in myopic eyes. In 35 of the 37 eyes that were evaluated, 90° sulcus-to-sulcus was greater than 0° sulcus-to-sulcus.

The mean 90° sulcus-to-sulcus was 12.51 mm, compared with a mean 0° sulcus-to-sulcus of 12.19 mm (P < .01). Using scanning-slit topography, the mean 0° white-to-white diameter measurements were 11.73 mm compared with and 12.20 mm using partial coherence

interferometry biometry.

"The correlations were good between 0° sulcus-to-sulcus and 0° white-to-white with [partial coherence interferometry] biometry and scanning-slit topography in emmetropic eyes, but weak between 0° sulcus-to-sulcus and 0° white-to-white in myopic eyes," the authors wrote.