Abstract
Purpose: :
Individuals with oculocutaneous albinism are predisposed to visual system abnormalities affecting the retina and the retinofugal projections, which may lead to reduced visual acuity and infantile nystagmus syndrome (INS). Due to absence of an established mammalian animal model, mechanisms underlying infantile nystagmus syndrome remain incompletely understood. In this study, we screened wildtype mice of varying pigmentation for ocular motor abnormalities in order to identify a possible animal model for INS.
Methods: :
Two albino strains (Crl:CD1(ICR), BALB/cAnNTac), the grey DBA/1JbomTac, the brown 129S6/SvEvTac and the black C57BL/6NTac strains were screened using infrared-oculography. Varying visual stimuli (white background, stationary pattern, rotating pattern) were displayed to the full or anterior visual field of the restrained mouse.
Results: :
We found spontaneous nystagmus, specifically jerks and oscillations, in hypopigmented mice under all experimental conditions, while ocular positions in pigmented mice were nearly stable (median absolute eye velocity in pigmented strains: mean < 0.4 deg/s; in hypopigmented strains: mean 0.8-3.4 deg/s).In hypopigmented mice, full visual field optokinetic stimuli elicited an optokinetic response (OKR) in the correct direction, albeit with superimposed oscillations. Anterior visual field optokinetic stimuli, however, evoked reversed OKR in these strains. The latter has been reported before for albino mice and is a well known feature of INS.
Conclusions: :
Based on our results, we endorse the investigated hypopigmented mouse strains as new animal models for INS.
Keywords: eye movements • nystagmus • ocular motor control