April 2009
Volume 50, Issue 13
ARVO Annual Meeting Abstract  |   April 2009
Biphasic Scleral Response During the Recovery From Induced Myopia: Is the Choroid Involved?
Author Affiliations & Notes
  • J. A. Summers Rada
    Dept of Cell Biology, Univ of Oklahoma Hlth Sci Ctr, Oklahoma City, Oklahoma
  • R. H. Folger
    Dept of Cell Biology, Univ of Oklahoma Hlth Sci Ctr, Oklahoma City, Oklahoma
  • Footnotes
    Commercial Relationships  J.A. Summers Rada, None; R.H. Folger, None.
  • Footnotes
    Support  NIH Grant EY009391
Investigative Ophthalmology & Visual Science April 2009, Vol.50, 3930. doi:
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      J. A. Summers Rada, R. H. Folger; Biphasic Scleral Response During the Recovery From Induced Myopia: Is the Choroid Involved?. Invest. Ophthalmol. Vis. Sci. 2009;50(13):3930.

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      © ARVO (1962-2015); The Authors (2016-present)

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Purpose: : During the recovery form deprivation myopia (myopic defocus), the rate of proteoglycan synthesis in the posterior sclera decreases co-incident with a deceleration of axial elongation. The choroid has been implicated in the regulation of scleral proteoglycan synthesis, possibly through the synthesis and secretion of scleral growth inhibitors. Therefore these studies were carried out to attempt to establish a causal relationship between choroidal secretion and the inhibition of scleral proteoglycan synthesis during the recovery from induced myopia.

Methods: : Chicks (n = 5 - 15 in each group) were form vision deprived for 10 days followed by a recovery period in which occluders were removed for 0, 3,6,12, 24 - 192 hours. Scleras and choroids (5 mm punches) were isolated from control and treated eyes. The rate of proteoglycan synthesis by isolated sclera of control and treated eyes was estimated in vitro by the incorporation of 35SO4 in CPC-precipitable glycosaminoglycans. Choroids from control and treated eyes were placed in co-culture with untreated age-matched normal chick sclera for 20 - 24 hrs, after which time scleras were removed and scleral proteoglycan synthesis rates determined.

Results: : Following 10 days of form deprivation (0 hrs recovery) the rate of scleral proteoglycan synthesis was significantly increased in form deprived eyes as compared to controls (68.08% ± 22.46, p < 0.05). Following removal of occluders, a biphasic decline was observed in scleral proteoglycan synthesis: A rapid decline in proteoglycan synthesis (-7.91% per hr; r2 = 0.957) was observed over the first 12 hours of recovery, whereas a slow decline was observed from 12 - 96 hours (-0.23% per hr; r2 = 0.527). Proteoglycan synthesis rates gradually increased to control levels over the next 96 hours at a rate of 0.26% per hr. Scleral proteoglycan synthesis rates of untreated eyes were significantly increased when co-cultured with choroids isolated from 3 hr recovering eyes (+22%, p < 0.01), but were not significantly affected by co-culture with 6 hr recovering choroids.

Conclusions: : Scleral proteoglycan synthesis rapidly declines within hours of unrestricted vision (myopic defocus). This rapid decline is not mediated by secreted factors from the choroid, as measured in vitro.

Keywords: sclera • choroid • proteoglycans/glycosaminoglycans 

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