Accommodation, the Pupil, and Presbyopia

Ciuffreda, Kenneth J.

doi:10.1016/b978-0-7506-7524-6.50009-0

Cited by 66 publications

(136 citation statements)

References 115 publications

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“…The original theory of Kepler (1611) which referred to changes in the focus of vision obtained with the antero-posterior movement of lens (as occurs in some fish), received support from various observers, despite being established by several authors that such movements (around 10 mm) are not found in mammals, invalidating this theory (5) . Another possibility, that accommodation was related to changes in lens shape, it was suggested earlier by Descartes (1677) (2) . Much later, Helmholtz (1853-1856) (3) was able to demonstrate that the act of accommodation provided by the ciliary muscle was accompanied by an increase in curvature of both sides of the lens and an increase in its thickness.…”

Section: Historymentioning

confidence: 99%

“…Accommodation refers to the process whereby chances in the dioptric power of the crystalline lens occur so that an in-focus retinal image of an object of regard is obtained and maintained at the high-resolution fovea (1) . Although lenticular-based focusing was first proposed by Descartes, it was Thomas Young who initially demonstrated that changes in the crystalline lens itself were responsible for such focusing changes, and Helmholtz, who advanced the first basic but reasonably accurate explanation on the accommodative process (2) .…”

mentioning

confidence: 99%

“…It must also explain the changes found during the aging eye, especially after 40 years with the onset of presbyopia. Presbyopia refers to the slow, normal, naturally occurring, age-related, irreversible reduction in maximal accommodative amplitude (i.e., recession of the near point) sufficient to cause symptoms of blur and ocular discomfort or asthenopia at the customary near working distance (2) .…”

mentioning

confidence: 99%

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New concepts in accommodation and presbyopia

Santos-Neto

Alves

2011

Rev. bras.oftalmol.

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The authors conducted a review of classical and conflicting theories of accommodation and presbyopia. They make a critical comparison with the findings of magnetic resonance imaging (MRI) that have been developed in recent decades. Based on these studies, formulates a new approach on the subject, shifting the focus of the discussion of the lens to the posterior pole of the eye.Keywords: Ocular accommodation ; Presbyopia RESUMOOs autores revisaram as teorias clássicas e conflitantes sobre acomodação e presbiopia. E as compararam criticamente com os achados de imagem por ressonância magnética (MRI) que têm se desenvolvido nas últimas décadas. Baseado nestes estudos, formulam uma nova abordagem sobre o tema, mudando o foco da discussão do cristalino para o polo posterior do olho.

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Section: Historymentioning

confidence: 99%

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confidence: 99%

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confidence: 99%

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New concepts in accommodation and presbyopia

Santos-Neto

Alves

2011

Rev. bras.oftalmol.

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“…0.3 D (maximum 0.75 D) were formed to study VA variability within these groups. The 0.3 D limit was arbitrarily selected because it represents the mid-point between the results of experimental studies of depth of focus in eyes with a 3-mm pupil (Ciuffreda 1998).…”

Section: Methodsmentioning

confidence: 99%

Random measurement error in visual acuity measurement in clinical settings

Leinonen

Laakkonen

Laatikainen

2005

Acta Ophthalmologica Scandinavica

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ABSTRACT.Purpose: To estimate the random measurement error in visual acuity (VA) determination in the clinical environment in cataractous, pseudophakic and healthy eyes. Methods: The VAs of patients referred for cataract surgery or consultation by ophthalmic professionals were re-examined and the VA results for distance using projector acuity charts were compared. Refractive errors were also remeasured. A total of 99 eyes (41 cataractous, 36 pseudophakic and 22 healthy eyes) were examined. The healthy comparison group consisted of hospital staff. Only one eye of each person and eyes with Snellen VAs of 0.3-1.3 (logMAR 0.52 to -0.11) were included. The mean time interval between the first and second examinations was 45 days. Results: The estimated standard deviation of measurement error (SDME) of repeated VA measurements of all eyes was logMAR 0.06. Eyes with the lowest VA (0.3-0.45) had the largest variability (SDME logMAR 0.09), and eyes with VA ‡ 0.7 had the smallest (SDME logMAR 0.04). The variability may be partly explained by the line size progression in lower VAs, partly by the difference in the remeasurement of the refractive error. The difference in the average VA between examinations 1 and 2 (logMAR 0.15 versus 0.12) was considered to be of some interest because it indicates that some learning effect is possible. Conclusion: Visual acuity results in clinical settings have a certain degree of inherent variability. In this series variability ranged from SDME logMAR 0.04 (eyes with good vision) to logMAR 0.09 (in the lower vision group) in the Snellen VA range of 0.3-1.3. Changes should be judged with caution, especially in cases of decreased VA.

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“…It is widely accepted that DOF blur is one of the pictorial depth cues [1]- [5]. It is also reported that the accommodation of the eyes is driven by DOF blur in retinal images [6], [7], and its motor control and sensory feedback could give depth sensation [8]. Blum et al reported that visual discomfort of viewing stereoscopic displays can be mitigated by adding DOF blur [9].…”

Section: Introductionmentioning

confidence: 99%

A Gaze-Reactive Display for Simulating Depth-of-Field of Eyes When Viewing Scenes with Multiple Depths

Orikasa

Okatani

2016

IEICE Trans. Inf. & Syst.

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SUMMARYThe the depth-of-field limitation of our eyes causes outof-focus blur in the retinal images. The blur dynamically changes whenever we change our gaze and accordingly the scene point we are looking at changes its depth. This paper proposes an image display that reproduces retinal out-of-focus blur by using a stereoscopic display and eye trackers. Its purpose is to provide the viewer with more realistic visual experiences than conventional (stereoscopic) displays. Unlike previous similar systems that track only one of the viewer's eyes to estimate the gaze depth, the proposed system tracks both eyes individually using two eye trackers and estimates the gaze depth from the convergence angle calculated by triangulation. This provides several advantages over existing schemes, such as being able to deal with scenes having multiple depths. We describe detailed implementations of the proposed system and show the results of an experiment conducted to examine its effectiveness. In the experiment, creating a scene having two depths using two LCD displays together with a half mirror, we examined how difficult it is for viewers to distinguish between the real scene and its virtual reproduction created by the proposed display system. The results of the experiment show the effectiveness of the proposed approach. key words: depth of field, eye tracker, stereoscopic display

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Accommodation, the Pupil, and Presbyopia

Cited by 66 publications

References 115 publications

New concepts in accommodation and presbyopia

New concepts in accommodation and presbyopia

Random measurement error in visual acuity measurement in clinical settings

A Gaze-Reactive Display for Simulating Depth-of-Field of Eyes When Viewing Scenes with Multiple Depths

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