Refractive errors

Schiefer, Ulrich; Kraus, Christina N.; Baumbach, Peter; Ungewiß, Judith; Michels, Ralf

doi:10.3238/arztebl.2016.0693

Cited by 30 publications

(25 citation statements)

References 32 publications

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“…A cross-sectional study conducted amongst Polish children aged six to eighteen years compared the effect of different types of electric lights in different rooms in their homes on the prevalence of refractive errors [ 42 ]. Refractive errors are caused by a defect in the eye shape which results in difficulty focusing on an image, causing blurred vision [ 55 ]. Only a higher prevalence of hyperopia (farsightedness) amongst those using fluorescent lights compared to incandescent lights (15% vs. 11%) in the kitchen were statistically significant of the five refractive errors assessed in the study [ 42 ].…”

Section: Resultsmentioning

confidence: 99%

Lighting in the Home and Health: A Systematic Review

Osibona

Solomon

Fecht

2021

IJERPH

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Poor housing is an important determinant of poor health. One key aspect of housing quality is lighting. Light is important for visual performance and safety, and also plays a vital role in regulating human physiological functions. This review aims to synthesise existing evidence on the relationship between lighting in the home and health and recommends areas for future research. Three databases were searched for relevant literature using pre-defined inclusion criteria. Study quality was assessed using the Newcastle Ottawa Scale. Extracted data were qualitatively synthesised according to type of lighting (natural light, artificial light and light at night) and stratified by broad health domains (physical, mental and sleep health). Of the 4043 records retrieved, 28 studies met the inclusion criteria. There was considerable heterogeneity in light exposure metrics used and specific health outcome assessed by the studies. Lighting in the home can negatively affect health but the current evidence base is limited to a small number of studies in different domains of light and health. Further research surrounding specific health outcomes is required to better inform housing quality assessments and lighting practises in the home.

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Section: Resultsmentioning

confidence: 99%

Lighting in the Home and Health: A Systematic Review

Osibona

Solomon

Fecht

2021

IJERPH

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“…This investigation was conducted by determining the material properties of each hydrogel material through tensile testing, modelling the contact lenses fitting process using finite element analysis, and using light raytracing analysis, to measure the effective power change induced by the lens. A clinically acceptable EPC was included in the analysis as |∆P| ≤ 0.25 [28,29]. This value was determined by considering the fact that, in clinical practice, trial lenses are varied in increments of 0.25 D.…”

Section: Discussionmentioning

confidence: 99%

Simulation of the Effect of Material Properties on Soft Contact Lens On-Eye Power

et al. 2019

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Purpose: To evaluate the variation in the optical power achieved following soft contact lens eye fitting for spherical and cylindrical lenses with differing hydrogel material properties. Methods: Uniaxial tensile tests were performed on four hydrogel materials 77% water-content (w-c) hydrogel, 74% w-c blue silicone hydrogel, 74% w-c clear silicone hydrogel, and 64% w-c clear hydrogel (shortly referred to as H77p0, SiH74p5-blue, SiH74p5-clear, and H64p0-clear), under loading conditions that would be expected in vivo. Finite element models of the cornea and contact lens interaction were generated using spherical and cylindrical lenses with powers varying from −10 to +20 D; overall diameters of either 13.5, 14.0, or 14.5 mm; and with material properties matching those determined through experimental testing. Results: The moduli of elasticity for each of the tested hydrogel materials were 0.195 ± 0.027 MPa, 0.277 ± 0.019 MPa, 0.279 ± 0.01 MPa, and 0.457 ± 0.013 MPa for H77p0, SiH74p5-blue, SiH74p5-clear, and H64p0 respectively. The calculated values of effective power change (EPC) showed strong negative correlations with lens power. This was particularly apparent in the higher end of the lens power spectrum (over +5 D), where each of the materials demonstrated a highly linear reduction in EPC with increased lens power. Conclusions: Soft contact lenses composed of a stiffer hydrogel are far more resilient to changes in EPC across the lower end of the lens power spectrum (−10 to +5 D). Beyond this range, the material choice does not have a significant effect on the EPC.

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“…Since the clinical visual acuity test is carried out at a distance of 6.0 m which induces a 0.167 D accommodation, this power is considered as clinically negligible. Therefore, the trial lenses are in 0.25 D steps and EPCs were considered to be clinically acceptable if |ΔP| ≤ 0.25 D [27, 28].…”

Section: Discussionmentioning

confidence: 99%

Simulated optical performance of soft contact lenses on the eye

et al. 2019

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Purpose To evaluate the impact of soft contact lens eye-fit on optical power by computational modelling and to produce correction maps for reversing this impact during the design process. Methods Finite element models of spherical and toric hydrogel contact lenses at varying nominal powers of -20 D to +20 D, base curves radii (R 1b ) of 8.2, 8.5, 8.8 mm, and overall diameters (d 3 ) of 14.5, 15.0, 15.5 mm were generated. Lenses were fitted to computational eye models generated with human eyes’ topography data. Combined eye-lens simulations were run under the boundary conditions of the tears’ surface tension between the contact lens and the eye in addition to the eyelid blink pressure. Lens optical zone power changes were calculated through computational light-ray tracing methods following each simulation. Results Effective power changes (EPC) were affected negatively for all toric simulated lenses with power varying from -20 D to +20 D. Spherical lenses demonstrated similar behaviour, however with some positive EPC over the power range from -20 D to -10 D for spherical power (SPH) lenses. EPC assessment was between +0.25 D and -0.5 D for most lenses, however, lenses with prescriptions from +10 D to +20 D incurred EPC outside this range. The spherical lenses showed a maximum effective power change of +1.046 ± 0.338 D (Average Eye), and a minimum of -3.278 ± 0.731 D (Steep Eye). Similarly, the toric lenses showed a maximum of +1.501 ± 0.338 D (Average Eye), and a minimum of -3.514 ± 0.731 D (Steep Eye). EPC trends, along with minimum and maximum power, generally increased negatively as nominal lens prescription increased positively. Contact lens base curve selection affected the assessed effective power change for both spherical and toric lenses. The effect from lens total diameter for spherical lenses was less substantial than that for toric lenses. Conclusions This study considered the impact of soft contact lens design parameters on effective optical power changes (EPC) after eye-fit. Spherical lenses experienced more EPC of clinical significance (>0.25 D) than toric lenses. Both types of lenses, spherical and toric (simple astigmatism), demonstrated similar trends in EPC on fitting from -20 D to +20 D, with lenses in the extremely positive and the extremely negative prescriptions demonstrating the highest EPCs. The lens base curve impacted the extent of EPC observed, with flatter base curves experiencing less power change. Diameter proved to impact toric lenses more than spherical ones, however generally the diameter has less effect on power change than base curve selection.

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Refractive errors

Abstract: SUMMARYBackground: All over the world, refractive errors are among the most frequently occuring treatable disturbances of visual function. Ametropias have a prevalence of nearly 70% among adults in Germany and are thus of great epidemiologic and socio-economic relevance.

Cited by 30 publications

References 32 publications

Lighting in the Home and Health: A Systematic Review

Lighting in the Home and Health: A Systematic Review

Simulation of the Effect of Material Properties on Soft Contact Lens On-Eye Power

Simulated optical performance of soft contact lenses on the eye

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