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 Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (11) Citing Articles via Google Scholar Google Scholar Articles by Phillips, J. R. Articles by McBrien, N. A. Search for Related Content PubMed PubMed Citation Articles by Phillips, J. R. Articles by McBrien, N. A.

Pressure-Induced Changes in Axial Eye Length of Chick and Tree Shrew: Significance of Myofibroblasts in the Sclera

From the Department of Optometry and Vision Sciences, University of Melbourne, Parkville, Victoria, Australia.

PURPOSE. To investigate the change in axial eye dimensions resulting from stretching the sclera by acute elevation of intraocular pressure (IOP).

METHODS. IOP was increased to 100 mm Hg for 1 hour through an intravitreal cannula, while ocular component dimensions were monitored every 10 minutes with A-scan ultrasound in anesthetized animals (10 chicks and 10 tree shrews). In addition, immunocytochemical detection of -smooth muscle actin (-SMA) using a monoclonal antibody was conducted in the sclera of the tree shrew and the chick.

RESULTS. In both species, axial eye length immediately and significantly (P < 0.0001) increased on elevation of IOP to 100 mm Hg: chick to 103.9%, tree shrew to 101.2% (mean percentage of original measured at 15 mm Hg). After 1 hour of maintained pressure, chick eyes showed a further significant increase in axial length (to 108.6%), but axial length of tree shrew eyes decreased (to 100.3%) to the point that it was not significantly different from the original value at 15 mm Hg. Immunocytochemical studies of age-matched tissue demonstrated the presence of -SMA–containing fibroblasts (myofibroblasts) within tree shrew but not chick sclera.

CONCLUSIONS. Elevation of IOP caused axial elongation of chick eyes, but a consistent reduction in axial length of tree shrew eyes. The presence of myofibroblasts, demonstrated in tree shrew but not chick sclera, suggests that the reduction in axial length of tree shrew eyes may have been caused by activation of a contractile mechanism involving scleral myofibroblasts. Such a mechanism may play a role in the regulation of eye size and refractive development.

This article has been cited by other articles:

				A. I. Jobling, A. Gentle, R. Metlapally, B. J. McGowan, and N. A. McBrien Regulation of Scleral Cell Contraction by Transforming Growth Factor-{beta} and Stress: COMPETING ROLES IN MYOPIC EYE GROWTH J. Biol. Chem., January 23, 2009; 284(4): 2072 - 2079. [Abstract] [Full Text] [PDF]

				S. A. Read, M. J. Collins, and D. R. Iskander Diurnal Variation of Axial Length, Intraocular Pressure, and Anterior Eye Biometrics Invest. Ophthalmol. Vis. Sci., July 1, 2008; 49(7): 2911 - 2918. [Abstract] [Full Text] [PDF]

				N. A. McBrien, R. Metlapally, A. I. Jobling, and A. Gentle Expression of Collagen-Binding Integrin Receptors in the Mammalian Sclera and Their Regulation during the Development of Myopia Invest. Ophthalmol. Vis. Sci., November 1, 2006; 47(11): 4674 - 4682. [Abstract] [Full Text] [PDF]

				J C H Tan, F B Kalapesi, and M T Coroneo Mechanosensitivity and the eye: cells coping with the pressure. Br J Ophthalmol, March 1, 2006; 90(3): 383 - 388. [Abstract] [Full Text] [PDF]