Fluorophotometry as a diagnostic tool for the evaluation of dry eye disease

BACKGROUND: Dry eye disease is a common debilitating ocular disease. Current diagnostic tests used in dry eye disease are often neither sensitive nor reproducible, making it difficult to accurately diagnose and determine end points for clinical trials, or evaluate the usefulness of different medications in the treatment of dry eye disease. The recently developed fluorophotometer can objectively detect changes in the corneal epithelium by quantitatively measuring its barrier function or permeability. The purpose of the study is to investigate the use of corneal fluorescein penetration measured by the fluorophotometer as a diagnostic tool in the evaluation of dry eye patients. METHODS: Dry eye patients (16 eyes), who presented with a chief complaint of ocular irritation corresponding with dry eye, low Schirmer's one test (<10 mm after 5 minutes) and corneal fluorescein staining score of more than two, were included in the study. Normal subjects (16 eyes), who came for refraction error evaluation, served as controls. Institutional Review Board (IRB) approved consent was obtained before enrolling the subjects in the study and all questions were answered while explaining the risks, benefits and alternatives. All Fluorophotometry of the central corneal epithelium was done utilizing the Fluorotron Master (TradeMark). Each eye had a baseline fluorescein scan performed, after which 50 l of 1% sodium fluorescein dye was instilled. Three minutes later, the fluorescein was washed with 50 ml of normal saline. Fluorescein scans were then started immediately after washing and were recorded at 10, 20, 40, and 60 minutes thereafter. The corneal peak values of fluorescein concentration were recorded within the central cornea in both dry eyes and in controls. RESULTS: Ten minutes after fluorescein installition, patients with dry eye disease averaged a five-fold increase in corneal tissue fluorescein concentration (mean = 375.26 ± 202.67 ng/ml) compared with that of normal subjects (mean = 128.19 ± 85.84 ng/ml). Sixty minutes after dye installation, patients with dry eye disease still revealed higher corneal tissue fluorescein concentration (mean = 112.87 ± 52.83 ng/ml) compared with that of controls (mean = 40.64 ± 7.96 ng/ml), averaging a three-fold increase. CONCLUSION: Patients with dry eye disease demonstrated an increased corneal permeability and a slower rate of elimination to topically administered fluorescein when measured by the fluorophotometer. This suggests that fluorophotometry may serve as a valuable quantitative and objective tool for the diagnosis of dry eye disease, and in following patients' response to new treatment modalities. Fluorophotometry may serve as an objective non-invasive tool for end-point analysis in clinical trials of new treatments for dry eye disease

Mineralogía, geoquímica y algunos aspectos genéticos de la mina El Diamante- Nariño (Colombia).

The Diamante mine is located in the southwestern part of Colombia on the west flank of the Occidental Andes&nbsp;Cordillera. The fluid associated with gold mineralization has a range of salinity between 1.7 to 5.8 wt % NaCl&nbsp;equivalent. Densities vary from 0.58 to 0.92 g/cc. Homogenization temperature averages range between 228-340°C. d34Spyrite&nbsp;values of –7.1 to –5.3‰ and d34SSS&nbsp;= -5.7‰ suggest a mixing of sulfur with sedimentary and&nbsp;magmatic origin. The d18O and dD values for the fluids are 7.6 to 9.6‰ and -74 to -83‰, respectively. The&nbsp;isotopic and fluid inclusion data of ore fluids suggest that the gold mineralization at the Diamante mine may&nbsp;have evolved from mixing of magmatic and meteoric fluids possibly related to intrusion of the nearby Piedrancha&nbsp;Granodiorite of late Miocene age. The gold deposition is attributed to destabilization of the bisulfide complex&nbsp;as a result of decrease of the sulfur activity, through sulfide deposition and/or H2S loss.La mina El Diamante, localizada en la parte Suroccidental de Colombia, se encuentra compuesta por venas&nbsp;cuarzosas enriquecidas en oro. Análisis de inclusiones fluidas, han permitido establecer que el fluido asociado&nbsp;con la mineralización tiene un rango que varía entre 1.7 a 5.8 NaCl equivalente en peso, con un rango de&nbsp;temperatura de homogeneización entre 228-340°C.&nbsp;Los valores de d34Spyrite&nbsp;obtenidos con Isótopos estables de - 7.1 a - 5.3‰ y el valor de d34SSS&nbsp;= -5.7‰ indican&nbsp;para el azufre un origen mixto: sedimentario y magmático. Los valores de d18O y dD de los fluidos fluctúan&nbsp;entre 7.6 a 9.6‰ y -74 a - 83‰ respectivamente. Los datos de isótopos e inclusiones fluidas sugieren que la&nbsp;mineralización aurífera de la mina El Diamante se desarrolló a partir de la mezcla de aguas meteóricas con&nbsp;aguas magmáticas, y posiblemente relacionada a la intrusión del Stock de Piedrancha de edad Mioceno&nbsp;Tardío. La deposición del oro es atribuida a la desestabilización del complejo bisulfuro, como resultado de la&nbsp;disminución de actividad del azufre a través de la deposición y/o perdida de H2S

Suppression of the near-infrared OH night sky lines with fibre Bragg gratings - first results

The background noise between 1 and 1.8 microns in ground-based instruments is dominated by atmospheric emission from hydroxyl molecules. We have built and commissioned a new instrument, GNOSIS, which suppresses 103 OH doublets between 1.47 - 1.7 microns by a factor of ~1000 with a resolving power of ~10,000. We present the first results from the commissioning of GNOSIS using the IRIS2 spectrograph at the AAT. The combined throughput of the GNOSIS fore-optics, grating unit and relay optics is ~36 per cent, but this could be improved to ~46 per cent with a more optimal design. We measure strong suppression of the OH lines, confirming that OH suppression with fibre Bragg gratings will be a powerful technology for low resolution spectroscopy. The integrated OH suppressed background between 1.5 and 1.7 microns is reduced by a factor of 9 compared to a control spectrum using the same system without suppression. The potential of low resolution OH suppressed spectroscopy is illustrated with example observations. The GNOSIS background is dominated by detector dark current below 1.67 microns and by thermal emission above 1.67 microns. After subtracting these we detect an unidentified residual interline component of ~ 860 +/ 210 ph/s/m^2/micron/arcsec^2. This component is equally bright in the suppressed and control spectra. We have investigated the possible source of the interline component, but were unable to discriminate between a possible instrumental artifact and intrinsic atmospheric emission. Resolving the source of this emission is crucial for the design of fully optimised OH suppression spectrographs. The next generation OH suppression spectrograph will be focussed on resolving the source of the interline component, taking advantage of better optimisation for a FBG feed. We quantify the necessary improvements for an optimal OH suppressing fibre spectrograph design.Comment: Accepted for publication in MNRAS. 15 pages, 18 figure