Validation of a method to measure light distortion surrounding a source of glare

Our objective was to validate a new device dedicated to measure the light disturbances surrounding bright sources of light under different sources of potential variability. Twenty subjects were involved in the study. Light distortion was measured using an experimental prototype (light distortion analyzer, CEORLab, University of Minho, Portugal) comprising twenty-four LED arrays panel at 2 m. Sources of variability included: intrasession and intersession repeated measures, pupil size (3 versus 6 mm), defocus (þ0.50) correction for the working distance, angular resolution (15 deg versus 30 deg), temporal stimuli presentation, and pupil size. Size, shape, location, and irregularity parameters have been obtained. At a low speed of presentation of the stimuli, changes in angular resolution did not have an effect on the results of the parameters measured. Results did not change with pupil size. Intensity of the central glare source significantly influenced the outcomes. Examination time was reduced by 30% when a 30 deg angular resolution was explored instead of 15 deg. Measurements were fast and repeatable under the same experimental conditions. Size and shape parameters showed the highest consistency, whereas location and irregularity parameters showed lower consistency. The system was sensitive to changes in the intensity of the central glare source but not to pupil changes in this sample of healthy subjects.

Development and psychometric properties of ECPICID-AVC to measure informal caregivers’ skills when caring for older stroke survivors at home

Introduction: Informal caregivers provide a significant part of the total care needed by dependent older people poststroke. Although informal care is often the preferred option of those who provide and those who receive informal care, informal caregivers often report lack of preparation to take care of older dependent people. This article outlines the development and psychometric testing of informal caregivers’ skills when providing care to older people after a stroke – ECPICID-AVC. Design: Prospective psychometric instrument validation study. Methods: Eleven experts participated in a focus group in order to delineate, develop and validate the instrument. Data were gathered among adult informal caregivers (n = 186) living in the community in Northern Portugal from August 2013 to January 2014. Results: The 32-item scale describes several aspects of informal caregiver’s skills. The scale has eight factors: skill to feed/hydrate by nasogastric feeding, skill to assist the person in personal hygiene, skill to assist the person for transferring, skill to assist the person for positioning, skill to provide technical aids, skill to assist the person to use the toilet, skill to feed/hydrate and skill to provide technical aids for dressing/undressing. Analysis demonstrated adequate internal consistency (Cronbach’s alpha = 0.83) and good temporal stability 0.988 (0.984–0.991). Conclusion: The psychometric properties of the measurement tool showed acceptable results allowing its implementation in clinical practice by the nursing community staff for evaluating practical skills in informal caregivers when providing care to older stroke survivors living at home.

Corrigendum to “Short-term changes in light distortion in orthokeratology subjects"

Artigo completo publicado na revista "BioMed Research International, (2015), 1-7" e disponível no RepositóriUM em: http://hdl.handle.net/1822/33375

Light-distortion analysis as a possible indicator of visual quality after refractive lens exchange with diffractive multifocal intraocular lenses

METHODS: Refractive lens exchange was performed with implantation of an AT Lisa 839M (trifocal) or 909MP (bifocal toric) IOL, the latter if corneal astigmatism was more than 0.75 diopter (D). The postoperative visual and refractive outcomes were evaluated. A prototype light-distortion analyzer was used to quantify the postoperative light-distortion indices. A control group of eyes in which a Tecnis ZCB00 1-piece monofocal IOL was implanted had the same examinations. RESULTS: A trifocal or bifocal toric IOL was implanted in 66 eyes. The control IOL was implanted in 18 eyes. All 3 groups obtained a significant improvement in uncorrected distance visual acuity (UDVA) (P < .001) and corrected distance visual acuity (CDVA) (P Z .001). The mean uncorrected near visual acuity (UNVA) was 0.123 logMAR with the trifocal IOL and 0.130 logMAR with the bifocal toric IOL. The residual refractive cylinder was less than 1.00 D in 86.7% of cases with the toric IOL. The mean light-distortion index was significantly higher in the multifocal IOL groups than in the monofocal group (P < .001), although no correlation was found between the light-distortion index and CDVA. CONCLUSIONS: The multifocal IOLs provided excellent UDVA and functional UNVA despite increased light-distortion indices. The light-distortion analyzer reliably quantified a subjective component of vision distinct from visual acuity; it may become a useful adjunct in the evaluation of visual quality obtained with multifocal IOLs.

Comparing different methods to measure biofilm thickness: the techniques are: optical coherence tomography, confocal laser scanning microscopy and low load compression test

Dissertação de mestrado integrado em Engenharia Biomédica (área de especialização em Engenharia Clínica)