Optical coherence tomography and the proximal lacrimal drainage system: a major review

Purpose To provide a major review of the literature on diagnostic and therapeutic implications, techniques, and utility of anterior segment optical coherence tomography (OCT) for the proximal lacrimal drainage system (PLDS). Methods The authors performed a PubMed search of articles published in the English language on anterior segment OCT for the proximal lacrimal drainage system. Data captured include evolution, techniques, diagnostic utility, therapeutic monitoring, outcomes, and limitations. Specific emphasis was laid on addressing the existing lacunae and the current practice patterns. Results The PLDS parameters that can be studied by OCT include punctal shape and morphology, external and internal punctum diameters, punctum depth and area, intra-punctal tear meniscus, punctal reserve, punctum-canalicular junction, canalicular diameter at various depths, canalicular depth, canalicular cross-sectional area, canalicular volume, and fluid meniscus characteristics. Normative data is now available from across the globe. Several punctal and canalicular disorders show characteristic OCT features and have adjunctive value in diagnosis. Post-operative OCT imaging can help in monitoring the outcomes of selected surgical procedures and medical therapy. OCT studies have raised doubts about the previous beliefs of vertical canalicular height and the definition of punctal stenosis. OCT dacryography (OCTD) and 3-dimensional punctal and canalicular imaging are promising modalities to further explore the anatomy, physiology, and pathophysiology of the PLDS. Conclusion Optical coherence tomography techniques are increasingly playing a significant role in diagnosing and managing proximal lacrimal drainage disorders. Further improvements in imaging techniques, better resolution, standardized definitions, and measurements of punctal and canalicular parameters will expand its clinical usage and give impetus to minimally invasive lacrimal surgeries.