Purchase this article with an account.
A Gentle, JE Martin, NA McBrien; Differential Expression of Collagen Types I, III and V in the Sclera of Myopic Eyes: A Precursor to Fibril Diameter Changes? . Invest. Ophthalmol. Vis. Sci. 2002;43(13):2449.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Purpose: The development of myopia is associated with reduced scleral collagen fibril diameter at the posterior pole of the eye in both humans and animal models. However, this reduction in fibril diameter occurs much later in myopia development than the decreases in scleral thickness, dry weight and collagen accumulation. The present study investigated expression levels of types III and V collagen, important factors in determining heterotypic fibril diameter, in conjunction with type I collagen expression. Methods: Myopia was induced in tree shrews (n=7) through the monocular deprivation of pattern vision for 5 days. The untreated eye served as a paired, genetic control and untreated animals served as age-matched controls (n=4). Collagen types I, III and V mRNA expression were investigated in scleral samples using tree shrew-specific primers and real-time PCR. Data was normalised to expression of the housekeeping gene HPRT, which has previously been shown not to alter in myopic eyes. Results: Expression of type I collagen was significantly reduced in the sclera of eyes developing myopia, when comparison was made to fellow control eyes (-207%, p<0.05) and normal eyes (p<0.05). However, mRNA expression levels of type III (+29%, p=0.82) and type V (-16%, p=0.83) collagen were not significantly different to control or normal eyes. The reduction in type I collagen production resulted in an increase in the relative ratio of type III/type I (+22%) and type V/type I (+25%) collagen mRNA in the sclera of myopic eyes. Conclusion: Reduced type I collagen synthesis contributes to the reduction in collagen accumulation that has previously been reported in eyes developing myopia. However, there is no evidence to indicate that the expression of types III and V collagen follows a similar pattern. We speculate that, as in the cornea, the relative ratio of newly synthesised type V collagen to newly synthesised type I collagen is important in the gradual accumulation of smaller diameter collagen fibrils which has been reported in the sclera of myopic eyes.
This PDF is available to Subscribers Only