Optical coherence tomography imaging of the proximal lacrimal system

There are currently no routinely used imaging modalities for the proximal lacrimal system. Optical Coherence Tomography (OCT) is a safe and non-invasive method of high resolution cross-sectional imaging of tissue microstructures using infra-red radiation. In this study we investigate whether OCT may be used to image the punctum and proximal canaliculus.

A cohort of healthy subjects with normal ocular anatomy and no symptoms of epiphora were prospectively invited to enrol. Spectral OCT images of the lower punctae were captured with a Topcon 3D Optical Coherence Tomography 2000 machine. Measurements were made of the maximal punctal diameter, canalicular diameter and canalicular depth. Our data for depth of the vertical canaliculus was compared to the widely quoted figure of 2 mm using a two-tailed t-test to check for a statistically significant difference at p < 0.05.

Thirty-six punctae of 18 subjects were scanned. The punctum was recognisable on the OCT image in all cases. The mean depth, width and cross- sectional area of the visualised canaliculi were 0.753 mm (SD 0.216), 0.110 mm (SD 0.067) and 9.49 × 10(-3)mm(2), respectively. The mean width of the punctum was 0.247 mm (SD 0.078).

We have demonstrated the first in-vivo high resolution images of normal punctal and vertical canalicular anatomy using spectral OCT. There is currently no other practical way to accurately image punctal and proximal canalicular morphology in vivo. OCT is a convenient and readily available tool in most eye clinics with resolution ideally suited for imaging of the punctum and proximal canaliculus.