Analysis of human crystalline lens curvature as a function of accommodative state and age

Koretz, Jane F.; Handelman, G. H.; Brown, Nicholas

doi:10.1016/0042-6989(84)90168-8

Cited by 124 publications

(60 citation statements)

References 11 publications

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“…Although several prior studies that have considered the effects of age on the lens have used even fewer lenses [6,7,25,32], the fact that the age related trends are observed despite the small number of lenses used indicates the significance of the age related changes. This study may be confirmed by a larger study, and preferably avoiding freezing the lenses before the measurement.…”

Section: Limitations Of the Test Methodsmentioning

confidence: 99%

Stiffness gradient in the crystalline lens

Weeber

Eckert

Pechhold

et al. 2007

Graefes Arch Clin Exp Ophthalmol

140

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: Limitations Of the Test Methodsmentioning

confidence: 99%

Stiffness gradient in the crystalline lens

Weeber

Eckert

Pechhold

et al. 2007

Graefes Arch Clin Exp Ophthalmol

140

147

View full text Add to dashboard Cite

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“…When accommodation occurs, lens equatorial diameter decreases (Storey and Rabie, 1987;Wilson, 1997;Glasser and Kaufman, 1999;Strenk et al, 1999), the lens anterior and posterior surface curvatures steepen (Brown, 1973;Koretz et al, 1984Koretz et al, , 1987Garner and Yap, 1997), anterior chamber depth decreases, lens axial thickness increases (Storey and Rabie, 1983;Koretz et al, 1987;Beers and Van der Heijde, 1996) and the posterior lens surface generally moves posteriorly (Brown, 1973;Beauchamp and Mitchell, 1985;Drexler et al, 1997). The accommodative change in shape of the young lens is brought about by the force the capsule exerts on the lens (Fincham, 1925(Fincham, , 1937Campbell, 1998, 1999;Glasser et al, 2001).…”

Section: Introductionmentioning

confidence: 99%

“…A-scan ultrasonography has been used to measure static changes in ocular biometry with accommodation in monkeys using both Edinger-Westphal (EW) and pharmacological stimulated accommodation (Koretz et al, 1987). Partial coherence interferometry (Drexler et al, 1997) and Scheimpflug photography (Brown, 1973;Koretz et al, 1984Koretz et al, , 1987Koretz et al, , 1997Dubbelman et al, 2003) have also been used to measure static biometric changes during accommodation in humans.…”

Section: Introductionmentioning

confidence: 99%

The relationship between refractive and biometric changes during Edinger–Westphal stimulated accommodation in rhesus monkeys

Vilupuru

Glasser

2005

Experimental Eye Research

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Experiments were undertaken to understand the relationship between dynamic accommodative refractive and biometric (lens thickness (LT), anterior chamber depth (ACD) and anterior segment length (ASL=ACD+LT)) changes during Edinger-Westphal stimulated accommodation in rhesus monkeys. Experiments were conducted on three rhesus monkeys (aged 11·5, 4·75 and 4·75 years) which had undergone prior, bilateral, complete iridectomies and implantation of a stimulating electrode in the Edinger-Westphal (EW) nucleus. Accommodative refractive responses were first measured dynamically with video-based infrared photorefraction and then ocular biometric responses were measured dynamically with continuous ultrasound biometry (CUB) during EW stimulation. The same stimulus amplitudes were used for the refractive and biometric measurements to allow them to be compared. Main sequence relationships (ratio of peak velocity to amplitude) were calculated. Dynamic accommodative refractive changes are linearly correlated with the biometric changes and accommodative biometric changes in ACD, ASL and LT show systematic linear correlations with increasing accommodative amplitudes. The relationships are relatively similar for the eyes of the different monkeys. Dynamic analysis showed that main sequence relationships for both biometry and refraction are linear. Although accommodative refractive changes in the eye occur primarily due to changes in lens surface curvature, the refractive changes are well correlated with A-scan measured accommodative biometric changes. Accommodative changes in ACD, LT and ASL are all well correlated over the full extent of the accommodative response.

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“…Fincham (17) , in 1937, based on anatomical and physiological data also tried to convince everyone (and mistakenly) that the thesis Helmholtz was possible, rather than the Tscherning theory (8) , which also was based on anatomical and physiological data (but much nearer to the current reality). Koretz et al (9,11) , with data from more recent imaging studies, formulated a theory similar to Tscherning, observing the possible action of the vitreous on lens, during the accommodation process.…”

Section: A New Approachmentioning

confidence: 99%

“…This fact was unknown at the time of Helmholtz and thus there is no report that correlates a mechanism other. But today we know that both mechanisms are intimately linked (9)(10)(11)(12)(13) .…”

Section: The Mechanism Of the Ocular Emmetropizationmentioning

confidence: 99%

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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Analysis of human crystalline lens curvature as a function of accommodative state and age

Cited by 124 publications

References 11 publications

Stiffness gradient in the crystalline lens

Stiffness gradient in the crystalline lens

The relationship between refractive and biometric changes during Edinger–Westphal stimulated accommodation in rhesus monkeys

New concepts in accommodation and presbyopia

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