Dynamic optical coherence tomography imaging of the lacrimal passage with an extrinsic contrast agent

A major review on punctal stenosis: Part II: Updated therapeutic interventions, complications, and outcomes

We continue our review of on punctal stenosis by providing a detailed discussion of management modalities, their complications, and outcomes. There is a significant change in the understanding of punctal and peripunctal anatomy, puncto-canalicular junction, and the lacrimal pump mechanisms. While the snip punctoplasty procedures are still practiced, there is an increasing trend toward nonincisional procedures. The nonincisional procedures in select cases appear to be equally effective as the incisional ones. Although simple to use, punctal plugs never became the mainstay of treatment because of design issues and the inability to address the coexisting canalicular stenosis. Placing stents only in the lower punctum in cases of upper and lower punctal stenosis should be discouraged, and management needs to address punctal stenosis and not which punctum is involved. Several types of stents are used in the management of punctal stenosis, mostly based on surgeon's preference. The benefits of adjuvant mitomycin C are uncertain. In view of literature on how stent biofilms can themselves cause chronic inflammation, placing them for prolonged periods should be reviewed and debated. Enhanced understanding of the molecular pathogenesis of punctal stenosis and addressing the current controversies in management would help standardize the therapeutic interventions available in the lacrimal armamentarium.

Coherent light scattering from cellular dynamics in living tissues

This review examines the biological physics of intracellular transport probed by the coherent optics of dynamic light scattering from optically thick living tissues. Cells and their constituents are in constant motion, composed of a broad range of speeds spanning many orders of magnitude that reflect the wide array of functions and mechanisms that maintain cellular health. From the organelle scale of tens of nanometers and upward in size, the motion inside living tissue is actively driven rather than thermal, propelled by the hydrolysis of bioenergetic molecules and the forces of molecular motors. Active transport can mimic the random walks of thermal Brownian motion, but mean-squared displacements are far from thermal equilibrium and can display anomalous diffusion through Lévy or fractional Brownian walks. Despite the average isotropic three-dimensional environment of cells and tissues, active cellular or intracellular transport of single light-scattering objects is often pseudo-one-dimensional, for instance as organelle displacement persists along cytoskeletal tracks or as membranes displace along the normal to cell surfaces, albeit isotropically oriented in three dimensions. Coherent light scattering is a natural tool to characterize such tissue dynamics because persistent directed transport induces Doppler shifts in the scattered light. The many frequency-shifted partial waves from the complex and dynamic media interfere to produce dynamic speckle that reveals tissue-scale processes through speckle contrast imaging and fluctuation spectroscopy. Low-coherence interferometry, dynamic optical coherence tomography, diffusing-wave spectroscopy, diffuse-correlation spectroscopy, differential dynamic microscopy and digital holography offer coherent detection methods that shed light on intracellular processes. In health-care applications, altered states of cellular health and disease display altered cellular motions that imprint on the statistical fluctuations of the scattered light. For instance, the efficacy of medical therapeutics can be monitored by measuring the changes they induce in the Doppler spectra of livingex vivocancer biopsies.

[Optical coherence tomography in the diagnosis of pathologies of the horizontal portion of the lacrimal drainage system]

This article reviews literature on the use of optical coherence tomography in studying the anatomical structure of the proximal lacrimal drainage system, as well as in diagnosing its pathological changes. Determining the reference values of the parameters of the lacrimal punctum and the lacrimal canaliculus remains an important issue. The review describes the advantages and disadvantages of this method, as well as the prospects for its application in clinical practice.

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.

New Technologies in Clinical Trials in Corneal Diseases and Limbal Stem Cell Deficiency: Review from the European Vision Institute Special Interest Focus Group Meeting

To discuss and evaluate new technologies for a better diagnosis of corneal diseases and limbal stem cell deficiency, the outcomes of a consensus process within the European Vision Institute (and of a workshop at the University of Cologne) are outlined. Various technologies are presented and analyzed for their potential clinical use also in defining new end points in clinical trials. The disease areas which are discussed comprise dry eye and ocular surface inflammation, imaging, and corneal neovascularization and corneal grafting/stem cell and cell transplantation. The unmet needs in the abovementioned disease areas are discussed, and realistically achievable new technologies for better diagnosis and use in clinical trials are outlined. To sum up, it can be said that there are several new technologies that can improve current diagnostics in the field of ophthalmology in the near future and will have impact on clinical trial end point design.