Age-dependence of the optomechanical responses of ex vivo human lenses from India and the USA, and the force required to produce these in a lens stretcher: The similarity to in vivo disaccommodation
| Autor: | Esdras Arrieta, Fabrice Manns, Arthur Ho, Mukesh Taneja, Jean-Marie A. Parel, Robert C. Augusteyn, Pesala Veerendranath, Derek Nankivil, Ashik Mohamed |
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| Rok vydání: | 2011 |
| Předmět: |
Adult
Aging Accommodation Materials science Adolescent genetic structures India Dimensions In Vitro Techniques Human lens Article Nucleus law.invention Young Adult Ciliary body Optics In vivo law Age related Lens Crystalline Cadaver medicine Ciliary ring Humans EVAS stretching device Child Aged Aged 80 and over business.industry Infant Newborn Accommodation Ocular Infant Middle Aged Accommodative amplitude United States eye diseases Sensory Systems Sclera Lens (optics) Ageing Ophthalmology medicine.anatomical_structure Child Preschool Stress Mechanical sense organs business Ex vivo Biomedical engineering |
| Zdroj: | Vision Research. 51:1667-1678 |
| ISSN: | 0042-6989 |
| DOI: | 10.1016/j.visres.2011.05.009 |
| Popis: | The purpose of this study was to study the age-dependence of the optomechanical properties of human lenses during simulated disaccommodation in a mechanical lens stretcher, designed to determine accommodative forces as a function of stretch distance, to compare the results with in vivo disaccommodation and to examine whether differences exist between eyes harvested in the USA and India. Postmortem human eyes obtained in the USA ( n = 46, age = 6–83 years) and India ( n = 91, age = 1 day–85 years) were mounted in an optomechanical lens stretching system and dissected to expose the lens complete with its accommodating framework, including zonules, ciliary body, anterior vitreous and a segmented rim of sclera. Disaccommodation was simulated through radial stretching of the sectioned globe by 2 mm in increments of 0.25 mm. The load, inner ciliary ring diameter, lens equatorial diameter, central thickness and power were measured at each step. Changes in these parameters were examined as a function of age, as were the dimension/load and power/load responses. Unstretched lens diameter and thickness increased over the whole age range examined and were indistinguishable from those of in vivo lenses as well as those of in vitro lenses freed from zonular attachments. Stretching increased the diameter and decreased the thickness in all lenses examined but the amount of change decreased with age. Unstretched lens power decreased with age and the accommodative amplitude decreased to zero by age 45–50. The load required to produce maximum stretch was independent of age (median 80 mN) whereas the change in lens diameter and power per unit load decreased significantly with age. The age related changes in the properties of human lenses, as observed in the lens stretching device, are similar to those observed in vivo and are consistent with the classical Helmholtz theory of accommodation. The response of lens diameter and power to disaccommodative (stretching) forces decreases with age, consistent with lens nuclear stiffening. |
| Databáze: | OpenAIRE |
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