Five-year experience of tele-ophthalmology for diabetic retinopathy screening in a rural population. / Análisis de un programa de teleoftalmología para el cribado de retinopatía diabética en área rural tras cinco años.

OBJECTIVE: To identify the prevalence and risk factors of diabetic retinopathy (DR) among rural inhabitants included in a tele-ophthalmology program. To analyse diagnostic accuracy among primary care physicians, concordance with ophthalmologists, and financial savings. MATERIAL AND METHODS: An observational randomised study was conducted on 394 patients included in a tele-ophthalmology program (from January 2010 to January 2015). An analysis was performed on the clinical characteristics, DR findings in retinography images, and correspondence between the request for a second interpretation by an ophthalmologist, and previously established criteria for it: presence of moderate to severe DR, vision loss, poor image quality and/or intraocular pressure >22mmHg. Statistical analysis was performed using the SPSS program (Student t and χ(2) tests). RESULTS: DR prevalence was 12.1%. Patients with glycosylated haemoglobin values >7.68% or those treated with a combination of insulin and oral antidiabetic drugs showed a higher risk of DR (P<.05). 43.3% of patients correctly referred to ophthalmologists showed moderate to severe DR. Unnecessary referrals to specialists were improved from 91.7% in 2010 to 98.6% in 2014. It is estimated that the program has made a total saving of €152,550.45. CONCLUSIONS: Tele-ophthalmology programs are a useful tool in DR screening. Primary care physicians are able to distinguish patients who need specialist care, avoiding unnecessary referrals to ophthalmologists, and saving costs.

Supported metallocene catalysts by surface organometallic chemistry. Synthesis, characterization, and reactivity in ethylene polymerization of oxide-supported mono- and biscyclopentadienyl zirconium alkyl complexes: establishment of structure/reactivity relationships.

The reactions of CpZr(CH(3))(3), 1, and Cp(2)Zr(CH(3))(2), 2, with partially dehydroxylated silica, silica-alumina, and alumina surfaces have been carried out with careful identification of the resulting surface organometallic complexes in order to probe the relationship between catalyst structure and polymerization activity. The characterization of the supported complexes has been achieved in most cases by in situ infrared spectroscopy, surface microanalysis, qualitative and quantitative analysis of evolved gases during surface reactions with labeled surface, solid state (1)H and (13)C NMR using (13)C-enriched compounds, and EXAFS. 1 and 2 react with silica(500) and silica-alumina(500) by simple protonolysis of one Zr-Me bond by surface silanols with formation of a single well-defined neutral compound. In the case of silica-alumina, a fraction of the supported complexes exhibits some interactions with electronically unsaturated surface aluminum sites. 1 and 2 also react with the hydroxyl groups of gamma-alumina(500), leading to several surface structures. Correlation between EXAFS and (13)C NMR data suggests, in short, two main surface structures having different environments for the methyl group: [Al](3)-OZrCp(CH(3))(2) and [Al](2)-OZrCp(CH(3))(mu-CH(3))-[Al] for the monoCp series and [Al](2)-OZrCp(2)(CH(3)) and [Al]-OZrCp(2)(mu-CH(3))-[Al] for the bisCp series. Ethylene polymerization has been carried out with all the supported complexes under various reaction conditions. Silica-supported catalysts in the absence of any cocatalyst exhibited no activity whatsoever for ethylene polymerization. When the oxide contained Lewis acidic sites, the resulting surface species were active. The activity, although improved by the presence of additional cocatalysts, remained very low by comparison with that of the homogeneous metallocene systems. This trend has been interpreted on the basis of various possible parameters, including the (p-pi)-(d-pi) back-donation of surface oxygen atoms to the zirconium center.