Suchergebnisse

A computational predictive tool for assessing patient-specific corneal tissue properties is developed. This predictive tool considers as input variables the corneal central thickness (CCT), the intraocular pressure (IOP), and the maximum deformation amplitude of the corneal apex (U) when subjected to a non-contact tonometry test. The proposed methodology consists of two main steps. First, an extensive dataset is generated using Monte Carlo (MC) simulations based on finite element models with patient-specific geometric features that simulate the non-contact tonometry test. The cornea is assumed to be an anisotropic tissue to reproduce the experimentally observed mechanical behavior. A clinical database of 130 patients (53 healthy, 63 keratoconic and 14 post-LASIK surgery) is used to generate a dataset of more than 9000 cases by permuting the material properties. The second step consists of constructing predictive models for the material parameters of the constitutive model as a function of the input variables. Four different approximations are explored: quadratic response surface (QRS) approximation, multiple layer perceptron (MLP), support vector regressor (SVR), and K-nn search. The models are validated against data from five real patients. The material properties obtained with the predicted models lead to a simulated corneal displacement that is within 10% error of the measured value in the worst case scenario of a patient with very advanced keratoconus disease. These results demonstrate the potential and soundness of the proposed methodology. ; The research leading to these results has received funding from the European Union's Seven Framework Program managed by REA Research Executive agency http://ec.europa.eu/research/rea (FP7/2007–2013) under Grant Agreement FP7-SME-2013 606634, the Spanish Ministry of Economy and Competitiveness under the Grant Agreement DPI2014-54981R, the Government of Aragón (predoctoral contract of the author), the Ibercaja-CAI mobility program (mobility funding for research stay of the author) and the Swiss Federal Department of Economic Affairs, Education and Research (Federal Commission for Scholarships for Foreign Students).

Roman seals associated with collyria (Latin expression for eye drops /washes and lotions for eye maintenance) provide valuable information about eye care in the antiquity. These small, usually stone-made pieces bore engravings with the names of eye doctors and also the collyria used to treat an eye disease. The collyria seals have been found all over the Roman empire and Celtic territories in particular and were usually associated with military camps. In Hispania (Iberian Peninsula), only three collyria seals have been found. These findings speak about eye care in this ancient Roman province as well as about of the life of the time. This article takes a look at the utility and social significance of the collyria seals and seeks to give an insight in the ophthalmological practice of in the Roman Empire.

AIM: To analyse and characterize the pattern of working and mobile phone usage distances for common users of electronic devices and computers. METHODS: Transversal descriptive study consisting of a screening campaign evaluating the visual status of different professionals working with computers or electronic devices more than 2h per day. A total of 100 healthy patients with a mean age of 41.2 (range: 20-62) years were revised and subdivided according to job subgroups. A battery of screening tests was performed to all participants in a single session at the working environment of each of them, including measurement of the working distance (WD), arm length, and mobile phone usage distances (MPUD). RESULTS: The WD was significantly longer than MPUD (61.22±12.35 vs 32.22±6.35 cm; P<0.001). Likewise, MPUD was significantly shorter than the arm length (74.44±4.65 cm; P<0.001). A total of 4% (4/100) and 91% (91/100) of patients had a WD and MPUD of 40 cm or below, respectively. A weak although statistically significant correlation was found between WD and MPUD (r=0.387, P<0.001) as well as between WD and arm length (r=0.260, P=0.009). Statistically significant differences were detected among job subgroups in WD (P=0.021), being longer for militaries compared to university researchers and lecturers (P=0.025). CONCLUSION: Working and mobile phone usage distances vary significantly among common users of computers and digital devices, although the use of mobile phones tends to be performed at significantly closer distances. This parameter should be considered when planning any type of optical correction, especially for presbyopia.

AIM: To analyse and characterize the pattern of working and mobile phone usage distances (MPUD) for common users of electronic devices and computers. METHODS: Transversal descriptive study consisting of a screening campaign evaluating the visual status of different professionals working with computers or electronic devices more than 2h per day. A total of 100 healthy patients with a mean age of 41.2 (range: 20-62) years were revised and subdivided according to job subgroups. A battery of screening tests was performed to all participants in a single session at the working environment of each of them, including measurement of the working distance (WD), arm length, and MPUD. RESULTS: The WD was significantly longer than MPUD (61.22±12.35 vs 32.22±6.35 cm; P<0.001). Likewise, MPUD was significantly shorter than the arm length (74.44±4.65 cm; P<0.001). A total of 4% (4/100) and 91% (91/100) of patients had a WD and MPUD of 40 cm or below, respectively. A weak although statistically significant correlation was found between WD and MPUD (r=0.387, P<0.001) as well as between WD and arm length (r=0.260, P=0.009). Statistically significant differences were detected among job subgroups in WD(P=0.021), being longer for militaries compared to university researchers and lecturers (P=0.025). CONCLUSION: Working and mobile phone usage distances vary significantly among common users of computers and digital devices, although the use of mobile phones tends to be performed at significantly closer distances. This parameter should be considered when planning any type of optical correction, especially for presbyopia.