Presbyopia and the optical changes in the human crystalline lens with age

Glasser, Adrian; Campbell, Melanie C. W.

doi:10.1016/s0042-6989(97)00102-8

Cited by 523 publications

(342 citation statements)

References 58 publications

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“…Consequently, the stiffness of the human crystalline lens is thought to have an effect on the accommodative ability and the development of presbyopia [3,[18][19][20]. The young and soft crystalline lens is easy to deform, while the old lens is stiff, hard and unable to be deformed [3,18,31,32].…”

Section: Introductionmentioning

confidence: 99%

Stiffness gradient in the crystalline lens

Weeber

Eckert

Pechhold

et al. 2007

Graefes Arch Clin Exp Ophthalmol

141

147

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Background While the overall stiffness of the lens has been measured in a number of studies, the knowledge about the stiffness distribution within the lens is still limited. The purpose of this study was to determine the stiffness gradient in the human crystalline lens. A secondary purpose was to determine whether the stiffness gradient depends on age. Methods The local dynamic stiffness was measured in 10 human crystalline lenses (age range: 19 to 78 years). The lenses were stored at −70°C before being measured. The influence of freezing on the mechanical properties has been determined in a previous study. A small oscillating probe was used to measure the local dynamic shear modulus as a measure of lens stiffness. The measurements were taken in the cross-sectional plane through the lens equator. Results The local dynamic shear modulus varied with location for all tested lenses. The central stiffness of the oldest lens (78 years) was 10 4 times higher than the youngest (19 years) lens. The equatorial stiffness of the oldest lens was 10 2 times higher than the youngest lens. For the older lenses, the centre was 5.8-210 times stiffer than the periphery, as opposed to earlier results described by Fisher (1971), who found that the periphery was up to 3 times softer than the centre for lenses younger than 70-years-old. For the three youngest lenses (19 to 49 years), the periphery was 2.2-16.6 times stiffer than the centre. Conclusions The dynamic stiffness of the crystalline lens varies with location within the lens. The stiffness gradient depends on the age of the lens. The results of the 10 lenses indicate that the stiffness of both centre and periphery increase with age, but at a different rate.

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Section: Introductionmentioning

confidence: 99%

Stiffness gradient in the crystalline lens

Weeber

Eckert

Pechhold

et al. 2007

Graefes Arch Clin Exp Ophthalmol

141

147

View full text Add to dashboard Cite

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“…The localized posterior or outward movement of the anterior portion of the ciliary muscle toward the sclera, as suggested by this author from histologic analysis, was not visible by imaging techniques 13 . Also, his description concerning the insertion of the zonule conflicts with evidences provided by analysis of fresh human tissues and from scanning electron microscopic studies 15,16 . They show no insertion of equatorial bundles or any other zonular fibers at the iris root and anterior ciliary muscle ( Fig.…”

Section: The Mechanism Of Accommodationmentioning

confidence: 86%

“…A major factor in the loss of accommodation may be the increased stiffness of the aging lens with inability to respond to accommodative stimuli 21 . In general, the multitude of changes that occur in the eye resulting in presbyopia can be broadly grouped into three categories: lens and capsulebased theories, which consider changes in the elasticity and compliance of the lens and capsule; extralenticular theories which consider changes in the ciliary muscle and choroid; and geometric theories which consider changes in the geometry of the zonular attachments to the lens 15 .…”

Section: Presbyopiamentioning

confidence: 99%

“…Supporting this concept in agreement with extralenticular theories, Fuchs 2 first reported that cycloplegia is more effective in young eyes than old, and Duane 33 found the onset of cycloplegia to be more rapid in early presbyopes than nonpresbyopes. Moreover, if ciliary muscle wasting was significant, its vigorous exercise (e.g., hyperopia, prolonged near work) should postpone presbyopia and there is no evidence that this occurs 15,34 .…”

Section: Presbyopiamentioning

confidence: 99%

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Fisiologia da acomodação e presbiopia

Werner¹,

Trindade²,

Pereira³

et al. 2000

Arq. Bras. Oftalmol.

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“…In children and young adults, the internal lens of the eye is flexible enough that its anterior surface can bulge forward to increase the optical power. This change in shape occurs as tension on the supporting zonule fibers is released in response to forward movement of the ciliary processes caused by contraction of the ciliary muscle [37,77].…”

Section: The Eye As a Dynamic Optical Systemmentioning

confidence: 99%

A method for enhancing digital information displayed to computer users with visual refractive errors via spatial and spectral processing

Alonso¹

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., "A method for enhancing digital information displayed to computer users with visual refractive errors via spatial and spectral processing" (2007 We have read this dissertation and recommend that it be approved. Malek Adjouadi Roberto PanepucciShu-Ching Chen The dissertation of Miguel Alonso Jr is approved. Dean Vish Prasad College of Engineering and ComputingDean George Walker University Graduate School This research is based on a priori knowledge of the user's visual aberration, as measured by a wavefront analyzer. With this information it is possible to generate images that, when displayed to this user, will counteract his/her visual aberration. The method described in this dissertation advances the development of techniques for providing such compensation by integrating spatial information in the image as a means to eliminate some of the shortcomings inherent in using display devices such as monitors or LCD panels. Additionally, physiological considerations are discussed and integrated into the method for providing said compensation. viIn order to provide a realistic sense of the performance of the methods described, they were tested by mathematical simulation in software, as well as by using a single-lens high resolution CCD camera that models an aberrated eye, and finally with human subjects having various forms of visual aberrations. Experiments were conducted on these systems and the data collected from these experiments was evaluated using statistical analysis.The experimental results revealed that the pre-compensation method resulted in a statistically significant improvement in vision for all of the systems. Although significant, the improvement was not as large as expected for the human subject tests. Further analysis suggest that even under the controlled conditions employed for testing with human subjects, the characterization of the eye may be changing. This would require real-time monitoring of relevant variables (e.g. pupil diameter) and continuous adjustment in the pre-compensation process to yield maximum viewing enhancement.

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Presbyopia and the optical changes in the human crystalline lens with age

Cited by 523 publications

References 58 publications

Stiffness gradient in the crystalline lens

Stiffness gradient in the crystalline lens

Fisiologia da acomodação e presbiopia

A method for enhancing digital information displayed to computer users with visual refractive errors via spatial and spectral processing

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