Application of functional genomic technologies in a mouse model of retinal degeneration

Mouse experimental myopia has features of primate myopia

PURPOSE

Several recent studies have suggested that experimental myopia can be induced in mice. However, it is not clear what role the photopic visual input plays in this process and whether mouse myopia is similar to human myopia. The purpose of this study was to carry out an in vivo high-resolution analysis of changes in ocular components and refractive state of the eye upon induction of experimental myopia in mice.

METHODS

A high-resolution small animal MRI system and a high-resolution automated eccentric infrared photorefractor were used to analyze changes of the refractive state and ocular components in C57BL/6J mice associated with experimental myopia induced by diffusers and -25 D lenses under photopic conditions.

RESULTS

The authors found that both diffusers and -25 D lenses induce myopia in C57BL/6J mice under photopic conditions (continuous light, 200 +/- 15 lux). The extent of myopic shift induced by -25 D lenses was greater than the shift induced by diffusers (-15.2 +/- 0.7 D, lenses; -12.0 +/- 1.4 D, diffusers). Myopia in mice is attributed to an increase in size of the postequatorial segment of the eye. Experimental myopia in mice can be induced only during the susceptible period in postnatal development, which ends around postnatal day 67.

CONCLUSIONS

Both diffusers and spectacle lenses induce myopia in mice under photopic conditions, during the susceptible period in postnatal development. Myopia in mice is associated with elongation of the vitreous chamber of the eye, as in humans and nonhuman primates.

Analysis of postnatal eye development in the mouse with high-resolution small animal magnetic resonance imaging

PURPOSE

Studies of myopia in mice have been complicated by the difficulty in obtaining accurate measurements of small changes observed in the growing mouse eye in vivo and the lack of data on refractive eye development. The purpose of this study was to carry out an in vivo high-resolution analysis of mouse eye growth and refractive development.

METHODS

High-resolution small animal magnetic resonance imaging and high-resolution infrared photorefraction were used to analyze refractive development in postnatal day (P)21 to P89 C57BL/6J mice.

RESULTS

The growth of the mouse eye decelerated after P40. The eye maintained a slightly prolate shape during growth. The anterior chamber growth exhibited a similar pattern, whereas the corneal radius of curvature (CRC) increased linearly. The growth rate of the lens remained constant until P89. The lens "overgrew" the eye at P40, resulting in a decline in vitreous chamber depth. Mice showed myopic refractive errors at a younger age (-13.2 +/- 2.0 D; mean +/- SD, P21). The refractive errors stabilized around emmetropic values by P32 and remained emmetropic until P40. Mice became progressively hyperopic with age (+1.2 +/- 1.7 D, P67; +3.6 +/- 2.3 D, P89).

CONCLUSIONS

Development of ocular components in the mouse is similar to that of the tree shrew but different from that of higher primates and humans. Primary differences can be attributed to the age-related changes of the crystalline lens and CRC. In spite of these differences, mice appear to be able to achieve and maintain emmetropic refractive status at P32 to P40.