Meesmann Corneal Dystrophy; a Clinico-Pathologic, Ultrastructural and Confocal Scan Report

Purpose: To report the microstructural features of Meesmann corneal dystrophy (MCD) in two patients. Case Report: The first patient was a 10-year-old boy who presented with bilateral visual loss, diffuse corneal epithelial microcystic changes, high myopia and amblyopia. With a clinical impression of MCD, automated lamellar therapeutic keratoplasty was performed in his left eye. Histopathologic examination of the corneal button disclosed epithelial cell swelling and cyst-like intracytoplasmic inclusions. The cells contained moderate amounts of periodic acid-Schiff-positive and diastase-sensitive material (glycogen). Transmission electron microscopy revealed numerous vacuoles and moderate numbers of electron-dense membrane-bound bodies in the cytoplasm, similar to lysosomes, some engulfed by the vacuoles. The second patient was a 17-year-old female with a clinical diagnosis of MCD and episodes of recurrent corneal erosion. On confocal scan examination of both corneas, hyporeflective round-shaped areas measuring 6.8 to 41.4 μm were seen within the superficial epithelium together with irregular and ill-defined high-contrast areas in the sub-basal epithelial region. The subepithelial nervous plexus was not visible due to regional hyperreflectivity. Conclusion: This case report further adds to the microstructural features of Meesmann corneal dystrophy and suggests confocal scan as a non-invasive method for delineating the microstructural appearance of this rare dystrophy

The UK Infrared Telescope M33 monitoring project. III. Feedback from dusty stellar winds in the central square kiloparsec

We have conducted a near-infrared monitoring campaign at the UK InfraRed Telescope (UKIRT), of the Local Group spiral galaxy M33 (Triangulum). The main aim was to identify stars in the very final stage of their evolution, and for which the luminosity is more directly related to the birth mass than the more numerous less-evolved giant stars that continue to increase in luminosity. In this third paper of the series, we measure the dust production and rates of mass loss by the pulsating Asymptotic Giant Branch (AGB) stars and red supergiants. To this aim, we combined our time-averaged near-IR photometry with the multi-epoch mid-IR photometry obtained with the Spitzer Space Telescope. The mass-loss rates are seen to increase with increasing strength of pulsation and with increasing bolometric luminosity. Low-mass stars lose most of their mass through stellar winds, but even super-AGB stars and red supergiants lose $\sim40$% of their mass via a dusty stellar wind. More than three-quarters of the dust return is oxygenous. We construct a 2-D map of the mass-return rate, showing a radial decline but also local enhancements due to agglomerations of massive stars. We estimate a total mass-loss rate of 0.004--0.005 M$_\odot$ yr$^{-1}$ kpc$^{-2}$, increasing to $\sim0.006$ M$_\odot$ yr$^{-1}$ kpc$^{-2}$ when accounting for eruptive mass loss (e.g., supernov{\ae}); comparing this to the current star formation rate of $\sim0.03$ M$_\odot$ yr$^{-1}$ kpc$^{-2}$ we conclude that star formation in the central region of M\,33 can only be sustained if gas is accreted from further out in the disc or from circum-galactic regions.Comment: Accepted for publication in MNRA

Mass-loss rates of cool evolved stars in M33 galaxy

We have conducted a near-infrared monitoring campaign at the UK InfraRed Telescope (UKIRT), of the Local Group spiral galaxy M33 (Triangulum). In this paper, we present the dust and gas mass-loss rates by the pulsating Asymptotic Giant Branch (AGB) stars and red supergiants (RSGs) across the stellar disc of M33.Comment: A talk presented at the "IAU symposium 366 : The Origin of Outflows in Evolved Stars", to be published in the "IAU Proceedings Series