Search results for "ACCOMMODATION"

Accommodative Functions with Multifocal Contact Lenses: A Pilot Study

2011

PURPOSE: To evaluate accommodative response and facility in presbyopic patients fitted with several types of simultaneous-image multifocal contact lenses (CLs). METHODS: Six presbyopic patients, unadapted wearers of simultaneous-image bifocals, were fitted with the Focus Progressives and the low- and high-addition Pure Vision simultaneous vision multifocal CLs. Each individual wore each of the three types of lenses in successive random order. Accommodative response, accommodative facility, visual acuity, and contrast sensitivity at distance and near were evaluated in all cases. A control group of eight non-presbyopic patients was also studied. RESULTS: The mean age was 28.6 +/- 2.72 and 51.…

Tourism statistics and unobserved tourism: empirical evidences in Sicily

2013

Despite its strategic importance, accurately measuring visitor attendance has been a challenging and problematic exercise for tourism managers for decades. Consequently, the primary aim of tourism statistics of accurately quantify tourism flows has been only partially achieved; indeed at a lower territorial scale tourism statistics appear less precise and accurate. The aim of this paper is: to introduce the concept of unobserved tourism, by highlighting the main limits of official statistical systems (with a special focus on the European statistical system on tourism statistics; to formalize a theoretical model in which tourism nights and trips in a given destination are decomposed into obs…

Changes in accommodative responses with multifocal contact lenses: a pilot study.

2011

Our aim was to evaluate induced changes in pupil and accommodative response for different accommodative stimuli with three different multifocal contact lenses (CLs). Accommodative and pupil responses with three aspheric multifocal CLs of simultaneous focus center near (PureVision Low Add, PureVision High Add and Focus Progressives) for two accommodative stimuli of -2.5 and -4.00 D were recorded in 10 young subjects. Accommodative response, peak velocity, and time constant of accommodation and pupil constriction were assessed. The measurements were evaluated in all the participants with distance-single vision CLs and with the three multifocal CLs. The monocular measurements were performed in…

The effect of fractal contact lenses on peripheral refraction in myopic model eyes.

2014

Purpose: To test multizone contact lenses in model eyes: Fractal Contact Lenses (FCLs), designed to induce myopic peripheral refractive error (PRE). Methods: Zemax ray-tracing software was employed to simulate myopic and accommodation-dependent model eyes fitted with FCLs. PRE, defined in terms of mean sphere M and 90–180 astigmatism J180, was computed at different peripheral positions, ranging from 0 to 35 in steps of 5, and for different pupil diameters (PDs). Simulated visual performance and changes in the PRE were also analyzed for contact lens decentration and model eye accommodation. For comparison purposes, the same simulations were performed with another commercially available conta…

The Prevalence of Amblyopia in Germany

2015

Amblyopia is a condition in which reduced visual acuity is not directly caused by an organic defect (1). Amblyopia can develop when an infant or small child suffers from strabismus. Although both eyes are healthy, different images are formed on each fovea centralis (where vision is sharpest) and on other corresponding locations on the retina; this is in contrast to individuals without strabismus. To prevent double vision the child’s brain suppresses the image produced by one eye. Complete visual ability cannot develop in this eye during the sensitive phase of visual development (2). Approximately half of amblyopia cases (3) are caused by uncorrected higher refractive errors, which are frequ…

There is more to accommodation of the eye than simply minimizing retinal blur

2017

Eyes of children and young adults change their optical power to focus nearby objects at the retina. But does accommodation function by trial and error to minimize blur and maximize contrast as is generally accepted? Three experiments in monocular and monochromatic vision were performed under two conditions while aberrations were being corrected. In the first condition, feedback was available to the eye from both optical vergence and optical blur. In the second, feedback was only available from target blur. Accommodation was less precise for the second condition, suggesting that it is more than a trial-and-error function. Optical vergence itself seems to be an important cue for accommodation.

Depth-of-Field of the Accommodating Eye

2014

Our eyes project information from a three-dimensional world to a basically two-dimensional surface, corresponding to the photoreceptor plane in the retina. In theory, only one plane or surface of world can be in focus at one time. However, the eye exhibits a certain tolerance to out-of-focus images, a feature that is known as depth-of-focus (DOF). The corresponding distance range in which the objects are seen “clearly” is known as depth-of-field (DOFi). Although DOF and DOFi refer to an interval of distances or a dioptric range in the image and object space, respectively, both parameters define a similar concept and are usually interchangeable. This article will mainly refer to DOFi because…

Coping with and accommodating for linguistic and communicative problems in Asperger's syndrome : a grounded theory study of four autobiographies

2006

The Role of Industry in the Prevalence of Overeducation in Europe

2015

Abstract This paper performs a detailed study on the interaction between industry and the risk of overeducation using European Social Survey Round 5 data on 27 countries. Administrative and accommodation industries have the largest overeducation levels. When macro-level variables are included in the overeducation model, finance and public administration join these industries in being significantly more open to overeducation than manufacturing. Construction is the only industry with significantly lower overeducation risk than manufacturing. The exposure to overeducation in different industries reflects clear consequences of traditional association of men and women with different industries. …

Towards sustainable servicescape : tourists’ perspectives of accommodation service attributes

2023

The study uses content analysis to identify the sustainable attributes in 678 accommodation reviews from Finnish and Russian tourists published on the Tripadvisor website and examines the sustainability perceptions of these tourist groups. The servicescape framework was applied to the structuring of the attributes indicating sustain-ability in accommodation services. The sustainable attributes highlighted in the reviews were more frequently in the physical rather than in the social servicescape factor. The tourists also reported environmental sustainability attributes more often than those related to social, cultural and economic sustainability. Overall, the sustainable attributes were perc…