HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Heys, K. R. Articles by Truscott, R. J. W. Search for Related Content PubMed PubMed Citation Articles by Heys, K. R. Articles by Truscott, R. J. W.

Free and Bound Water in Normal and Cataractous Human Lenses

¹From the Save Sight Institute, Sydney University, Sydney, New South Wales, Australia; and the ²School of Chemistry, University of Wollongong, Wollongong, New South Wales, Australia.

PURPOSE. To analyze free and total water in human normal and cataractous lenses.

METHODS. Thermogravimetric analysis was used to determine total water, and differential scanning calorimetry was used for free water.

RESULTS. In normal human lenses, the total water content of the nucleus remained unchanged with age, but the state of the water altered. The ratio of free to bound water increased steadily throughout adult life. In a 20-year-old person, there was approximately one bound water molecule for each free water molecule in the lens center, whereas in a 70- to 80-year-old person, there were two free water molecules for each bound water molecule. This conversion of bound to free water does not appear to be simply a consequence of the aggregation of soluble crystallins into high molecular weight aggregates because studies with intact pig lenses, in which such processes were facilitated by heat, did not show similar changes. The region of the lens in which the barrier to diffusion develops at middle age corresponds to a transition zone in which the protein concentration is intermediate between that of the cortex and the nucleus. In cataractous lenses, the free-to-bound water ratio was not significantly different from that of age-matched normal lenses; however, total water content in the center of advanced nuclear cataractous lenses was slightly lower than in normal lenses.

CONCLUSIONS. As the human lens ages, bound water is progressively changed to free water. Advanced nuclear cataract may be associated with lower total hydration of the lens nucleus.