Search results for "ACCOMMODATION"
showing 10 items of 123 documents
The effect of longitudinal chromatic aberration on the lag of accommodation and depth of field.
2016
Purpose Longitudinal chromatic aberration is present in all states of accommodation and may play a role in the accommodation response and the emmetropisation process. We study the change of the depth of field (DOFi) with the state of accommodation, taking into account the longitudinal chromatic aberration. Methods Subjective DOFi was defined as the range of defocus beyond which the blur of the target (one line of optotypes of 0.1 logMAR shown on a black-and-white microdisplay, seen through different colour filters) was perceived as objectionable. The subject's eye was paralysed and different, previously-measured accommodative states (corresponding to the accommodative demands of 0D, 2D and …
The overall classification of residential buildings: Possible role of tourist EU Ecolabel award scheme
2012
Abstract The debate on the environmental performance of buildings and their classification is continuously rising and deeply involves all actors of the sector, from researchers to technicians and from owners to real estate managers. In the field, the EU has created a panel that is currently working on defining the criteria for attributing an Ecolabel award to a building. However, despite the enormous efforts made by administrative and academic institutions, a suitable and widely available scheme for operators to assess the environmental performance of a building is far from being established. To help provide a solution to the problem, the possibility of adopting the EU Ecolabel scheme estab…
Influence of different types of astigmatism on visual acuity
2016
[EN] Purpose To investigate the change in visual acuity (VA) produced by different types of astigmatism (on the basis of the refractive power and position of the principal meridians) on normal accommodating eyes. Methods The lens induced method was employed to simulate a set of 28 astigmatic blur conditions on different healthy emmetropic eyes. Additionally, 24 values of spherical defocus were also simulated on the same eyes for comparison. VA was measured in each case and the results, expressed in logMAR units, were represented against of the modulus of the dioptric power vector (blur strength). Results LogMAR VA varies in a linear fashion with increasing astigmatic blur, being the slope o…
Effect of Color on Contrast Sensitivity with Two Different Accommodative Stimuli
1993
We studied the influence of color and accommodation on the contrast sensitivity function (CSF). At the same time, we measured the effect of axial chromatic aberration (ACA) on the CSF. The CSF's of two observers were determined using red, green, blue, and white light, at 5- and 0.5-m viewing distances. At 5 m the CSF's were measured with natural vision and also with lenses which compensated the ACA. Results show that the effect of ACA on the CSF is to reduce the sensitivity to blue with respect to the red. The difference in sensitivity between these two colors is between 50 and 150% and varies with the frequency and the subject. When the ACA is compensated the influence of the color on the …
Tuvākā skaidra redzes punkta noteikšanu ietekmējošie faktori
2021
Darbs ir uzrakstīts angļu valodā uz 25 lapaspusēm. Tajā ir 20 attēli, 2 tabulas un 20 literatūras avoti. Darba mērķis ir novērtēt dažādu faktoru – acs zīlītes un stimula izmēra- ietekmi uz tuvākā skaidras redzes punkta novērtēšanu. Tuvākais skaidras redzes punkts tika noteikts ar “push-up” metodi. Mērījumi tika veikti ar stimulu izmēriem 20/20; 20/25 un 20/30 (Snellena frakcija). Acs zīlītes diametrs tika novērtēts, izmantojot šablonu. Rezultāti parādīja, ka, samazinoties stimula izmēram “push-up” metodē, zīlītes diametrs pieaug un tuvākais skaidras redzes punkts attālinās.
Amplitude, Latency, and Peak Velocity in Accommodation and Disaccommodation Dynamics
2017
The aim of this work was to ascertain whether there are differences in amplitude, latency, and peak velocity of accommodation and disaccommodation responses when different analysis strategies are used to compute them, such as fitting different functions to the responses or for smoothing them prior to computing the parameters. Accommodation and disaccommodation responses from four subjects to pulse changes in demand were recorded by means of aberrometry. Three different strategies were followed to analyze such responses: fitting an exponential function to the experimental data; fitting a Boltzmann sigmoid function to the data; and smoothing the data. Amplitude, latency, and peak velocity of …
Evaluation of the iridocorneal angle with accommodation using optical coherence tomography
2017
The changes in the iridocorneal angle structure during accommodation are assessed by means of anterior segment optical coherence tomography. Thirteen right eyes were included in the study. The device used for the measurement was the Visante® omni system. The stimuli were set up at different vergences (0.0 D, -1.5 D, and -3.0 D). The angle opening distance 500 and 750, the trabecular iris space area 500 and 750, and the scleral spur angle parameters were assessed at the nasal and temporal regions. The results in the iridotrabecular angle comparing the three accommodative states of the eye did not yield any statistically significant difference at nasal or temporal angle sections. In light of …
Determinants of individual tourist expenditure as a network: Empirical findings from Uruguay
2014
Abstract This paper introduces the use of graphical models for assessing the determinants of individual tourist spending. These models have the advantage of synthesizing and visualizing the relationships occurring within large sets of random variables, through an easy to interpret output. To this end, individual data from a large official survey of international tourists in Uruguay are used. Symmetric conditional independence structures are first investigated. Then subgraphs of each expenditure item's neighbourhood are extracted in order to assess the impact of main effects and interactions through proportional ordinal logistic regression. Results highlight the marginal role of socio-demogr…
Finnish health care and social work students' perceptions of Finnish-English code-switching : a survey study
2015
Englannin kielen asema kansainvälisenä valtakielenä on vaikuttanut sen leviämiseen myös Suomessa. Laajalle levinnyttä vierasta kieltä käyttävät Suomessa moninaisin tavoin eri-ikäiset ja taitotasoltaan erilaiset ihmiset. Siinä missä vieras kieli oli aiemmin kansakunnan ulkopuolelta tuleva asia, on vieraasta kielestä nykyaikana tullut enenevissä määrin myös yhteiskunnan sisäpuolella käytettävä kielellinen resurssi. Englannin kielen kohtaaminen ja sen käyttäminen ei enää edellytä kansainvälisiä kontakteja tai ulkomaanmatkoja, vaan englantia käytetään sujuvasti myös suomen kieltä äidinkielenään puhuvien kesken, osana pääasiallisesti suomenkielistä keskust…
Effect of Phenylephrine on the Accommodative System
2016
Accommodation is controlled by the action of the ciliary muscle and mediated primarily by parasympathetic input through postganglionic fibers that originate from neurons in the ciliary and pterygopalatine ganglia. During accommodation the pupil constricts to increase the depth of focus of the eye and improve retinal image quality. Researchers have traditionally faced the challenge of measuring the accommodative properties of the eye through a small pupil and thus have relied on pharmacological agents to dilate the pupil. Achieving pupil dilation (mydriasis) without affecting the accommodative ability of the eye (cycloplegia) could be useful in many clinical and research contexts. Phenylephr…