ON pathway mutations increase susceptibility to form-deprivation myopia

Area of Science:

• Ophthalmology
• Neuroscience
• Genetics

Background:

• ON pathway mutations, like in nob mice, are linked to altered refractive development and myopia.
• The specific role of the ON pathway versus the Nyx mutation in this phenotype remains unclear.

Purpose of the Study:

• To investigate whether the nob mouse phenotype is due to the Nyx mutation or abnormal ON pathway transmission.
• To assess the role of the ON pathway in refractive development and susceptibility to form-deprivation (FD) myopia using mGluR6-/- mice.

Main Methods:

• Refractive development and ocular biometry were measured in mGluR6-/- and wild-type (WT) mice from 4 to 16 weeks.
• Response to monocular FD was assessed weekly.
• Retinal dopamine (DA) and DOPAC levels were analyzed using high-performance liquid chromatography.

Main Results:

• mGluR6-/- mice exhibited increased myopia compared to WT controls under normal conditions.
• Monocular FD induced a significant myopic shift in mGluR6-/- mice, similar to nob mice.
• Reduced retinal DOPAC levels, indicating lower DA metabolism, were observed in mGluR6-/- mice, while DA levels remained similar.

Conclusions:

• Abnormal ON pathway transmission, not solely the Nyx mutation, contributes to altered refractive development and myopia susceptibility.
• Reduced retinal dopamine metabolism/turnover is associated with increased myopia in mice with ON pathway defect mutations.