Evaluation of a new method to visualize distribution and morphology of human corneal nerves (Adelta- and C-fibers) by means of fluorescence staining, confocal laser scanning microscopy, and 3-dimensional (3D) reconstruction. Trephinates of corneas with a diagnosis of Fuchs corneal dystrophy were sliced into layers of 200 microm thickness using a Draeger microkeratome (Storz, Germany). The anterior lamella was stained with the Life/Dead-Kit (Molecular Probes Inc.), examined by the confocal laser scanning microscope "Odyssey XL," step size between 0.5 and 1 microm, and optical sections were digitally 3D-reconstructed. Immediate staining of explanted corneas by the Life/Dead-Kit gave a complete picture of the nerves in the central human cornea. Thin nerves running parallel to the Bowman layer in the subepithelial plexus perforate the Bowman layer orthogonally through tube-like structures. Passing the Bowman layer, Adelta- and C-fibers can be clearly distinguished by fiber diameter, and, while running in the basal epithelial plexus, by their spatial arrangement. Adelta-fibers run straight and parallel to the Bowman layer underneath the basal cell layer. C-fibers, after a short run parallel to the Bowman layer, send off multiple branches penetrating epithelial cell layers orthogonally, ending blindly in invaginations of the superficial cells. In contrast to C-fibers, Adelta-fibers show characteristic bulbous formations when kinking into the basal epithelial plexus. Ex-vivo fluorescence staining of the cornea and 3D reconstructions of confocal scans provide a fast and easily reproducible tool to visualize nerves of the anterior living cornea at high resolution. This may help to clarify gross variations of nerve fiber patterns under various clinical and experimental conditions.

Uveal melanoma (UM) is fatal in ~50% of patients as a result of disseminated disease. This study aims to externally validate the Liverpool Uveal Melanoma Prognosticator Online V3 (LUMPO3) to determine its reliability in predicting survival after treatment for choroidal melanoma when utilizing external data from other ocular oncology centers. Anonymized data of 1836 UM patients from seven international ocular oncology centers were analyzed with LUMPO3 to predict the 10-year survival for each patient in each external dataset. The analysts were masked to the patient outcomes. Model predictions were sent to an independent statistician to evaluate LUMPO3’s performance using discrimination and calibration methods. LUMPO3’s ability to discriminate between UM patients who died of metastatic UM and those who were still alive was fair-to-good, with C-statistics ranging from 0.64 to 0.85 at year 1. The pooled estimate for all external centers was 0.72 (95% confidence interval: 0.68 to 0.75). Agreement between observed and predicted survival probabilities was generally good given differences in case mix and survival rates between different centers. Despite the differences between the international cohorts of patients with primary UM, LUMPO3 is a valuable tool for predicting all-cause mortality in this disease when using data from external centers.

Objectives This study was designed to examine the feasibility of ophthalmic magnetic resonance imaging (MRI) at 7 T using a local 6-channel transmit/receive radiofrequency (RF) coil array in healthy volunteers and patients with intraocular masses. Materials and Methods A novel 6-element transceiver RF coil array that makes uses of loop elements and that is customized for eye imaging at 7 T is proposed. Considerations influencing the RF coil design and the characteristics of the proposed RF coil array are presented. Numerical electromagnetic field simulations were conducted to enhance the RF coil characteristics. Specific absorption rate simulations and a thorough assessment of RF power deposition were performed to meet the safety requirements. Phantom experiments were carried out to validate the electromagnetic field simulations and to assess the real performance of the proposed transceiver array. Certified approval for clinical studies was provided by a local notified body before the in vivo studies. The suitability of the RF coil to image the human eye, optical nerve, and orbit was examined in an in vivo feasibility study including (a) 3-dimensional (3D) gradient echo (GRE) imaging, (b) inversion recovery 3D GRE imaging, and (c) 2D T₂-weighted fast spin-echo imaging. For this purpose, healthy adult volunteers (n = 17; mean age, 34 ± 11 years) and patients with intraocular masses (uveal melanoma, n = 5; mean age, 57 ± 6 years) were investigated. Results All subjects tolerated all examinations well with no relevant adverse events. The 6-channel coil array supports high-resolution 3D GRE imaging with a spatial resolution as good as 0.2 × 0.2 × 1.0 mm³, which facilitates the depiction of anatomical details of the eye. Rather, uniform signal intensity across the eye was found. A mean signal-to-noise ratio of approximately 35 was found for the lens, whereas the vitreous humor showed a signal-to-noise ratio of approximately 30. The lens-vitreous humor contrast-to-noise ratio was 8, which allows good differentiation between the lens and the vitreous compartment. Inversion recovery prepared 3D GRE imaging using a spatial resolution of 0.4 × 0.4 × 1.0 mm³ was found to be feasible. T₂-weighted 2D fast spin-echo imaging with the proposed RF coil afforded a spatial resolution of 0.25 × 0.25 × 0.7 mm³. Conclusions This work provides valuable information on the feasibility of ophthalmic MRI at 7 T using a dedicated 6-channel transceiver coil array that supports the acquisition of high-contrast, high–spatial resolution images in healthy volunteers and patients with intraocular masses. The results underscore the challenges of ocular imaging at 7 T and demonstrate that these issues can be offset by using tailored RF coil hardware. The benefits of such improvements would be in positive alignment with explorations that are designed to examine the potential of MRI for the assessment of spatial arrangements of the eye segments and their masses with the ultimate goal to provide imaging means for guiding treatment decisions in ophthalmological diseases.

Niemann-Pick type C1 (NPC1) disease is an inherited lysosomal storage disease caused by mutation of the Npc1 gene, resulting in a progressive accumulation of unesterified cholesterol and glycolipids in lysosomes of multiple tissues and leading to neurodegeneration and other disease. In Npc1 mutant mice, retinal degeneration including impaired visual function, lipofuscin accumulation in the pigment epithelium and ganglion cells as well as photoreceptor defects has been found. However, the pathologies of other individual cell types of the retina in Npc1 mutant mice are still not fully clear. We hypothesized that horizontal cells, amacrine cells, bipolar cells and glial cells are also affected in the retina of Npc1 mutant mice. Immunohistochemistry and electron microscopy were used to investigate pathologies of ganglion cells, horizontal cells, amacrine cells, bipolar cells, and optic nerves as well as altered activity of glial cells in Npc1 mutant mice. Electron microscopy reveals that electron-dense inclusions are generally accumulated in ganglion cells, bipolar cells, Müller cells, and in the optic nerve. Furthermore, abnormal arborisation and ectopic processes of horizontal and amacrine cells as well as defective bipolar cells are observed by immunohistochemistry for specific cellular markers. Furthermore, hyperactivity of glial cells, including astrocytes, microglial cells, and Müller cells, is also revealed. Our data extend previous findings to show multiple defects in the retina of Npc1 mutant mice, suggesting an important role of Npc1 protein in the normal function of the retina.