Effect of phenylephrine on static and dynamic accommodation.

PURPOSE: We tested the hypothesis that changes in accommodation after instillation of Phenylephrine Hydrochloride (PHCl) observed in some studies could be caused by changes in optics. METHODS: We performed two experiments to test the effects of PHCl on static and on dynamic accommodation in 8 and 6 subjects, respectively. Objective wavefront measurements were recorded of the static accommodation response to a stimulus at different distances or dynamic accommodation response to a sinusoidally moving stimulus (between 1 and 3 D of accommodative demand at 0.2Hz). The responses were characterized using two methods: one that takes into account the mydriatic optical effects on the accommodation produced by higher-order aberrations of the eye and another that takes into account only power changes paraxially due to the action of the ciliary muscle and regardless of the pupil size. RESULTS: When mydriatic optical effects were taken into account, differences in responses before and after PHCl instillation were 0.51±0.53 D, and 0.12±0.15, for static and dynamic accommodation, respectively, and were statistically significant (p0.313). CONCLUSIONS: The mydriatic effect of the PHCl causes optical changes in the eye that can reduce the objective and subjective measurement of accommodation

Learning robotics: a review

Purpose of Review: With the growing interest for STEM/STEAM, new robotic platforms are being created with different characteristics, extras and options. There are so many diverse solutions, that it is difficult for a teacher/student to choose the ideal one. This paper intends to provide an analysis to the most common robotic platforms existent on the market. The same is happening regarding robotic events all around the world, with objectives so distinctive, and with complexity from easy to very difficult. This paper also describes some of those events which occur in many countries. Recent Findings: As the literature is showing, there has been a visible effort from schools and educators to teach robotics from very young ages, not only because robotics is the future, but also as a tool to teach STEM/STEAM areas. But as time progresses, the options for the right platforms also evolves making difficult to choose among them. Some authors opt to first choose a robotic platform and carry on from there. Others choose first a development environment and then look for which robots can be programmed from it. Summary: An actual review on learning robotics is here presented, firstly showing some literature background on history and trends of robotic platforms used in education in general, the different development environments for robotics and finishing on competitions and events. A comprehensive characterization list of robotic platforms along with robotic competitions and events is also shown

Une nouvelle méthode AFM pour caractériser les propriétés piézoélectriques de nanostructures : Application pour la récupération d'énergie à partir de nanofils

National audienc

Age differences in central and peripheral intraocular pressure using a rebound tonometer

AIM: To evaluate the influence of age on the measurements and relationships among central and peripheral intraocular pressure (IOP) readings taken with a rebound tonometer. METHODS: The IOPs were measured using the ICare rebound tonometer on the right eyes of 217 patients (88 men and 129 women) aged 18–85 years (mean 45.9 (SD 19.8) years), at the centre and at 2 mm from the nasal and temporal limbus along the horizontal meridian. Three age groups were established: young (⩽30 years old; n = 75), middle aged (31–60 years old; n = 77) and old patients (>60 years old; n = 65). RESULTS: A high correlation was found between the central and peripheral IOP readings, with the central readings being higher than the peripheral ones. Higher IOP values for the central location were found in the younger patients. Older patients had significantly lower temporal IOP readings than those for the remaining two groups (p<0.001), whereas no significant differences were found among groups when IOP was measured at the central and nasal locations. A significant decrease was observed in the nasal and temporal IOP readings as the age increased (p = 0.011 and 0.006, respectively). CONCLUSION: Older patients had lower IOP values than the middle‐aged and younger patients in the temporal peripheral location. A negative correlation was found between age and IOP by rebound tonometry in the corneal periphery but not in its centre

Diurnal variations in ocular aberrations of human eyes

Purpose: To investigate the diurnal variations in ocular wavefront aberrations over two consecutive days in young adult subjects. Materials and methods: Measurements of both lower-order (sphero-cylindrical refractive powers) and higher-order (3rd and 4th order aberration terms) ocular aberrations were collected for 30 young adult subjects at ten different times over two consecutive days using a Hartmann-Shack aberrometer. Fifteen subjects were myopic and 15 were emmetropic. Five sets of measurements were collected each day at approximately 3 hourly intervals, with the first measurement taken at ~9 am and the final measurement at ~9 pm. Results: Spherical equivalent refraction (p = 0.029) and spherical aberration (p = 0.043) were both found to undergo significant diurnal variation over the two measurement days. The spherical equivalent was typically found to be at a maximum (i.e. most hyperopic) at the morning measurement, with a small myopic shift of 0.37 ± 0.15 D observed over the course of the day. The mean spherical aberration of all subjects (0.038 ± 0.048 μm) was found to be positive during the day and gradually became more negative into the evening, with a mean amplitude of change of 0.036 ± 0.02 μm. None of the other considered sphero-cylindrical refractive power components or higher-order aberrations exhibited significant diurnal variation over the two days of the experiment (p>0.05). Except for the lower-order astigmatism at 90/180 deg (p = 0.040), there were no significant differences between myopes and emmetropes in the magnitude and timing of the observed diurnal variations (p>0.05). Conclusions: Significant diurnal variations in spherical equivalent and spherical aberration were consistently observed over two consecutive days of measurement. Research and clinical applications requiring precise refractive error and wavefront measurements should take these diurnal changes into account when interpreting wavefront data