Abstract
Purpose: :
Methods to induce form deprivation (FD) in mice have included lid suture and gluing a small goggle to the fur around the eye. However, there are disadvantages to both methods. Lid suture may increase IOP in the proptosed mouse eye and may induce changes in corneal curvature, while gluing goggles around the eye requires an Elizabethan collar to keep the mouse from scratching the goggle off. Elizabethan collars prevent the mouse from grooming, leading to the development of corneal ulcers and making it impossible to accurately measure refractive error. In order to create a more successful approach to murine FD, we adapted a method currently being used to goggle tree shrews (Siegwart and Norton 1994), which utilizes a skull pedestal and frames to hold the goggle.
Methods: :
Goggling was performed at 28 days of age following baseline refractions with an automated photorefractor. After aneasthetic induction, the mouse skull was exposed and a pedestal molded across the lambda and sagittal sutures with dental acrylic. A small tube was embedded in the pedestal to hold the goggle frames in place. The frames consisted of two pieces, a circular portion to which a plastic goggle was glued and a straight piece that was positioned vertically on the opposite cheek, countering the pressure of the goggle. Nob mice, a model of type I congenital stationary night blindness, previously shown to be more susceptible to FD, were used. Compliance of goggle wear was monitored 2–3 times each day. After two weeks of FD, goggles were removed and refractive errors measured.
Results: :
Mice tolerated the pedestal and goggle frames very well and both maintained position for the duration of the experiment. The mice were still able to groom their faces which resulted in a healthy appearance to their fur and eyes. In our previous experiments in which goggles were glued around the eye and an Elizabethan collar was worn, 54% of the mice developed corneal ulcers and were eliminated from the study. With the pedestal and goggle frames, no mice developed corneal ulcers or any other health concern. The pedestal goggling method appears to induce approximately the same degree of FD as the previous goggling method. After 2 weeks of goggling, nob mice exhibited a myopic shift of ∼5 diopters.
Conclusions: :
Adopting the pedestal goggling methods to the murine model improved health by allowing continued grooming during FD trials. The goggles also elicit the desired myopic shift noted in previous goggling trials. Thus, the pedestal goggling method provides significant benefits in the mouse that cannot be matched by other methods.
Keywords: myopia • refractive error development • visual development