Anterior shift of zonular insertion onto the anterior surface of human crystalline lens with age

Sakabe, Isao; Oshika, Tetsuro; Lim, Seung Jeong; Apple, David J.

doi:10.1016/s0161-6420(98)93172-4

Cited by 53 publications

(35 citation statements)

References 11 publications

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“…The observation of Sakabe et al [33]that the zonule-free zone of the lens capsule decreases with age postnatally could be an artefact of measurement, since their experiments involved removing lens substance from the capsular bag by a phaco technique and refilling with a viscoelastic material prior to measurement. It may be that the more extensible capsule of the young lens allowed greater expansion of the capsular bag than in the old lens.…”

Section: Organisation and Remodelling In The Lensmentioning

confidence: 99%

The Ageing Lens

et al. 2000

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The human lens grows by a process of epithelial cell division at its equator and the formation of generations of differentiated fibre cells. Despite the process of continuous remodelling necessary to achieve growth within a closed system, the lens can retain a high level of light transmission throughout the lifetime of the individual, with the ability to form sharp images on the retina. Continuous growth of the lens solves the problem imposed by terminal differentiation within a closed, avascular system, from which cells cannot be shed. The lens fibre tips arch over the equator to meet anteriorly and posteriorly and form branching sutures of increasing complexity. The stages of branching may create the optical zones of discontinuity seen on biomicroscopy. The lens is exposed to the cumulative effects of radiation, oxidation and postranslational modification. These later proteins and other lens molecules in such a way as to impair membrane functions and perturb protein (particularly crystallin) organisation, so that light transmission and image formation may be compromised. Damage is minimised by the presence of powerful scavenger and chaperone molecules. Progressive insolublisation of the crystallins of the lens nucleus in the first five decades of life, and the formation of higher molecular weight aggregates, may account for the decreased deformability of the lens nucleus which characterises presbyopia. Additional factors include: the progressive increase in lens mass with age, changes in the point of insertion of the lens zonules, and a shortening of the radius of curvature of the anterior surface of the lens. Also with age, there is a fall in light transmission by the lens, associated with increased light scatter, increased spectral absorption, particularly at the blue end of the spectrum, and increased lens fluorescence. A major factor responsible for the increased yellowing of the lens is the accumulation of a novel fluorogen, glutathione-3-hydroxy kynurenine glycoside, which makes a major contribution to the increasing fluorescence of the lens nucleus which occurs with age. Since this compound may also cross-link with the lens crystallins, it may contribute to the formation of high-molecular-weight aggregates and the increases in light scattering which occur with age. Focal changes of microscopic size are observed in apparently transparent, aged lenses and may be regarded as precursors of cortical cataract formation.

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Section: Organisation and Remodelling In The Lensmentioning

confidence: 99%

The Ageing Lens

et al. 2000

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“…The extent of physiological zonular degradation during development and ageing is unknown although the zonular insertion onto the lens capsule has been observed to shift progressively anteriorly with age,57 suggesting that the ageing zonules undergo remodelling. Other factors may contribute to this shift, however, such as the changing curvature of the lens and contraction of the anterior capsule 58.…”

Section: Proteolytic Degradation Of Fibrillin-rich Microfibrils In Ocmentioning

confidence: 99%

Fibrillin and the eye

Ashworth

Kielty²,

McLeod³

2000

British Journal of Ophthalmology

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“…Cataract surgery in very elderly patients is challenging, as most of these patients have very dense nuclear cataracts. As age advances, there is a gradual reduction in corneal endothelial cell density and a zonule-free zone on the anterior capsule, 3 possibly predisposing elderly patients to higher complication rates. Despite these concerns, to our knowledge, there has been no study of cataract surgery in patients of 105 years and older.…”

Section: Discussionmentioning

confidence: 99%