Ultrasound biomicroscopy is the most successful in measuring sulcus diameter

Ciliary sulcus-to-sulcus (STS) diameter is most accurately measured using ultrasound biomicroscopy (UBM), according to a paper published in the Journal of Cataract and Refractive Surgery.

The study, led by Dr Julia Biermann, University Eye Hospital Freiberg im Breisgau, Germany, measured the STS diameter at 0, 45, 90 and 135 degrees using 35 MHz UBM. The Orbscan scanning-slit topography and the partial coherence interferometry (PCI) biometry (IOLMaster) were used to obtain the 0-degree automated horizontal white-to-white (WTW) diameter.

The 90˚ STS and the 0˚ STS were compared using the paired t test and the Pearson correlation was used to determine whether the 0˚ STS diameter could be predicted from the 0˚ WTW diameter.

In emmetropic and myopic eyes the mean SE refraction was −0.48 D ± 0.35 SD and −9.55 ± 3.70 D, respectively.

The 90˚ STS was greater than 0˚ STS in 35 of the 37 eyes studied. The mean 90˚ STS and 0˚ STS were 12.51 ± 0.43 mm and 12.19 ± 0.47 mm, respectively. The mean scanning-slit topography of 0˚ WTW diameters were 11.73 ± 0.37 mm and for the PCI biometry they were 12.20 ± 0.42 mm.

A strong correlation was found between 0˚ STS and 0˚ WTW with PCI biometry and scanning-slit topography in emmetropic eyes. However, the correlation was weaker in myopic eyes.

Overall, UBM is the most accurate way to measure sulcus diameter measurements. The study also suggests that WTW diameter is not suitable for determining a posterior chamber phakic intraocular lens (PC pIOL) diameter- especially in myopic eyes.