The suitability of guinea pigs as an experimental model for the study of human refractive errors

Abstract

At present, guinea pigs have been increasingly used for the study of human myopia. However, little is known about involvement of genetics, protein profiles and key molecules in axial growth of the guinea pig eyes in normal and manipulated visual conditions. This study evaluated the suitability of guinea pigs as an animal model for the study of human refractive errors based on comparison with other currently available species.

Various aspects of guinea pigs as an animal model have been researched in this study including the development of refraction and axial components of the guinea pig eye under a normal visual environment, genetic profiles of the guinea pig eye compared with human and mouse eyes, changes in protein profiles, refraction and axial components of the eye during myopic development and recovery (after termination of form deprivation or hyperopic defocus) in response to manipulated visual environments and pharmacological intervention using subconjunctival injection of apomorphine, a non-selective dopamine receptor agonist.

Guinea pigs had baseline ocular biometry comparable to humans under a normal visual environment and had similar process of emmetropization compared to humans. Moreover, guinea pigs appeared to be closer to humans than mice based on the ocular gene profiles. Axial myopia induced in guinea pigs was effective. The myopia and recovery were mainly due to changes in vitreous length and choroidal thickness. In respect of pharmacological intervention, a subconjunctival injection of apomorphine could inhibit form-deprivation myopia by slowing axial elongation of the eye in guinea pigs.

This study evaluated this myopic animal model comprehensively at the phenotypic genetic and proteomic levels. Guinea pigs are now only the second small animal with detailed gene and protein changes compared to humans. This study the first to use a pharmacological model with detailed dose response curves. Based on the evidence obtained guinea pigs an alternative to other currently available species for the study of the development of human refractive errors.