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Volume change of the ocular lens during accommodation.
Am J Physiol Cell Physiol. 2007 Aug; 293(2):C797-804.AJ

Abstract

During accommodation, mammalian lenses change shape from a rounder configuration (near focusing) to a flatter one (distance focusing). Thus the lens must have the capacity to change its volume, capsular surface area, or both. Because lens topology is similar to a torus, we developed an approach that allows volume determination from the lens cross-sectional area (CSA). The CSA was obtained from photographs taken perpendicularly to the lenticular anterior-posterior (A-P) axis and computed with software. We calculated the volume of isolated bovine lenses in conditions simulating accommodation by forcing shape changes with a custom-built stretching device in which the ciliary body-zonulae-lens complex (CB-Z-L) was placed. Two measurements were taken (CSA and center of mass) to calculate volume. Mechanically stretching the CB-Z-L increased the equatorial length and decreased the A-P length, CSA, and lens volume. The control parameters were restored when the lenses were stretched and relaxed in an aqueous physiological solution, but not when submerged in oil, a condition with which fluid leaves the lens and does not reenter. This suggests that changes in lens CSA previously observed in humans could have resulted from fluid movement out of the lens. Thus accommodation may involve changes not only in capsular surface but also in volume. Furthermore, we calculated theoretical volume changes during accommodation in models of human lenses using published structural parameters. In conclusion, we suggest that impediments to fluid flow between the aquaporin-rich lens fibers and the lens surface could contribute to the aging-related loss of accommodative power.

Authors+Show Affiliations

Dept of Ophthalmology, Mount Sinai School of Medicine, One Gustave L Levy Place, New York, NY 10029, USA.No affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, N.I.H., Extramural
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

17537805

Citation

Gerometta, R, et al. "Volume Change of the Ocular Lens During Accommodation." American Journal of Physiology. Cell Physiology, vol. 293, no. 2, 2007, pp. C797-804.
Gerometta R, Zamudio AC, Escobar DP, et al. Volume change of the ocular lens during accommodation. Am J Physiol, Cell Physiol. 2007;293(2):C797-804.
Gerometta, R., Zamudio, A. C., Escobar, D. P., & Candia, O. A. (2007). Volume change of the ocular lens during accommodation. American Journal of Physiology. Cell Physiology, 293(2), C797-804.
Gerometta R, et al. Volume Change of the Ocular Lens During Accommodation. Am J Physiol, Cell Physiol. 2007;293(2):C797-804. PubMed PMID: 17537805.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Volume change of the ocular lens during accommodation. AU - Gerometta,R, AU - Zamudio,A C, AU - Escobar,D P, AU - Candia,O A, Y1 - 2007/05/30/ PY - 2007/6/1/pubmed PY - 2007/9/21/medline PY - 2007/6/1/entrez SP - C797 EP - 804 JF - American journal of physiology. Cell physiology JO - Am. J. Physiol., Cell Physiol. VL - 293 IS - 2 N2 - During accommodation, mammalian lenses change shape from a rounder configuration (near focusing) to a flatter one (distance focusing). Thus the lens must have the capacity to change its volume, capsular surface area, or both. Because lens topology is similar to a torus, we developed an approach that allows volume determination from the lens cross-sectional area (CSA). The CSA was obtained from photographs taken perpendicularly to the lenticular anterior-posterior (A-P) axis and computed with software. We calculated the volume of isolated bovine lenses in conditions simulating accommodation by forcing shape changes with a custom-built stretching device in which the ciliary body-zonulae-lens complex (CB-Z-L) was placed. Two measurements were taken (CSA and center of mass) to calculate volume. Mechanically stretching the CB-Z-L increased the equatorial length and decreased the A-P length, CSA, and lens volume. The control parameters were restored when the lenses were stretched and relaxed in an aqueous physiological solution, but not when submerged in oil, a condition with which fluid leaves the lens and does not reenter. This suggests that changes in lens CSA previously observed in humans could have resulted from fluid movement out of the lens. Thus accommodation may involve changes not only in capsular surface but also in volume. Furthermore, we calculated theoretical volume changes during accommodation in models of human lenses using published structural parameters. In conclusion, we suggest that impediments to fluid flow between the aquaporin-rich lens fibers and the lens surface could contribute to the aging-related loss of accommodative power. SN - 0363-6143 UR - https://www.unboundmedicine.com/medline/citation/17537805/Volume_change_of_the_ocular_lens_during_accommodation_ L2 - http://journals.physiology.org/doi/full/10.1152/ajpcell.00094.2007?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub=pubmed DB - PRIME DP - Unbound Medicine ER -