Time-resolved three-dimensional technique for dynamic magnetic resonance dacryocystography.

IMPORTANCE: This study introduces a new technique in the assessment of nasolacrimal drainage with magnetic resonance imaging. BACKGROUND: To describe a new dynamic magnetic resonance dacryocystography (MRDCG) protocol and report normative findings on asymptomatic lacrimal drainage systems. DESIGN: A prospective observational study at the Royal Adelaide Hospital. PARTICIPANTS: Seventeen patients with unilateral epiphora were prospectively recruited. METHODS: Patients underwent dynamic MRDCG. The time-resolved angiography with interleaved stochastic trajectories (TWIST) sequence was used to visualise contrast flow through the lacrimal drainage system. MAIN OUTCOME MEASURES: Tear transit times and anatomical dimensions were measured. RESULTS: Dynamic MRDCG with TWIST sequence reliably demonstrated contrast flow. Tear transit times and anatomical dimensions were comparable to previously reported values in other imaging modalities. CONCLUSIONS AND RELEVANCE: Dynamic MRDCG provides good structural and temporal resolution to the assessment of lacrimal outflow obstructions. The physiological nature of this modality allows potential assessment for functional obstruction and future research on tear flow assessment.

Interobserver agreement on interpretation of conventional dacryocystography and dacryoscintigraphy findings: A retrospective single-centre study.

IMPORTANCE: This study assesses the interobserver agreement on dacryocystography (DCG) and dacryoscintigraphy (DSG) findings. BACKGROUND: There are no standard grading criteria to guide the interpretation of conventional DCG and DSG findings and therefore there may be a degree of subjectivity. This study evaluates the level of interobserver agreement in the interpretation of DCG and DSG findings. DESIGN: A retrospective observational study at the Royal Adelaide Hospital. PARTICIPANTS: A total of 165 patients who presented with epiphora with 276 DCGs and 290 DSGs performed were included in this study. METHODS: DCG and DSG images were obtained, anonymized, randomized and interpreted by three independent oculoplastic surgeons. Standard grading criteria were set for both DCG and DSG images. Data from all observers were analysed for interobserver agreement using Kappa (κ) statistics, generated using a variation of Cohen's kappa for multiple observers. MAIN OUTCOME MEASURES: Level of interobserver agreement (κ values) in the grading of DCG and DSG findings. RESULTS: There was an overall moderate interobserver agreement for DCG findings (κ = 0.55), with the highest agreement on interpreting canalicular obstruction (κ = 0.80), followed by proximal nasolacrimal duct obstruction (κ = 0.67) and normal patency (κ = 0.63). There was an overall fair interobserver agreement for DSG findings (κ = 0.36), with the best being moderate agreement (κ = 0.42-0.50) for interpreting pre-sac delay and post-sac proximal delay. CONCLUSIONS AND RELEVANCE: DCG offers good reliability in interpreting patent and obstructed systems. On the other hand, DSG has poor agreement and highlights some of the limitations in the ability to guide epiphora management.

Distribution and Activity of Mitochondrial Proteins in Vascular and Avascular Retinas: Implications for Retinal Metabolism.

Purpose: Understanding the energetics of retinal neurons and glia is crucial for developing therapies for diseases that feature deficits in nutrient or oxygen availability. Herein, we performed a detailed characterization of the distribution and activity of mitochondrial proteins in the vascularized retinas of rat and marmoset, and the avascular retinas of rabbit and guinea pig. Further, we delineated expression of ubiquitous mitochondrial creatine kinase (uMtCK). Methods: Expression of eight mitochondrial proteins was investigated using Western blotting, single- and double-labeling immunohistochemistry. Activities of cytochrome c oxidase, succinate dehydrgogenase, and isocitrate dehydrogenase were determined by enzyme histochemistry using unfixed tissue sections. Results: In vascularized retinas, immunoreactivities were characterized by strong, punctate labeling in the plexiform layers, photoreceptor inner segments, somas of various cell types, notably retinal ganglion cells (RGCs), and the basolateral surface of the retinal pigment epithelium. In avascular retinas, immunoreactivities featured intense labeling of inner segments, together with weak, but unambiguous, staining of both plexiform layers. RGCs were relatively enriched. In Müller cells of avascular retinas, mitochondria were restricted to scleral-end processes. For each species, enzyme activity assays yielded similar results to the protein distributions. Labeling for uMtCK in vascular and avascular retinas was fundamentally similar, being restricted to neuronal populations, most notably inner segments and RGCs. Of all of the mitochondrial proteins, uMtCK displayed the strongest labeling in avascular retinas. uMtCK was not detectable in Müller cells in any species. Conclusions: The current findings advance our understanding of the metabolic similarities and differences between vascular and avascular retinas.

Role of the nucleolus in neurodegenerative diseases with particular reference to the retina: a review.

The nucleolus has emerged as a key regulator of cellular growth and the response to stress, in addition to its traditionally understood function in ribosome biogenesis. The association between nucleolar function and neurodegenerative disease is increasingly being explored. There is also recent evidence indicating that the nucleolus may well be crucial in the development of the eye. In this present review, the role of the nucleolus in retinal development as well as in neurodegeneration with an emphasis on the retina is discussed.

Nerve Fiber Layer Infarcts in Thiamine Deficiency.

Thiamine deficiency classically manifests as the triad of Wernicke encephalopathy: acute confusional state, ataxic gait, and ocular motor dysfunction. However, most patients do no present with this classic triad. Optic neuropathy in thiamine deficiency is a rare manifestation and is usually associated with fundus appearances of optic disc swelling or optic disc pallor. We present 2 unique cases of thiamine deficiency where the fundus demonstrated peripapillary retinal nerve fiber layer thickening without florid disc swelling or pallor.