Inducement and Evaluation of a Murine Model of Experimental Myopia

Summary

In this protocol, we describe the full process of experimental myopia inducement in mice using newly designed eyeglasses and the technic needed for achieving stable and reproducible results in ocular parameter measurements.

Abstract

Murine model of myopia can be a powerful tool for myopia research because of the comparatively easy genetic manipulation. One way to induce myopia in animals is to put clear minus lenses in front of eyes for weeks (lens-induced myopia, LIM). However, extant protocols for inducement and evaluation vary from laboratory to laboratory. Here, we described a highly practical and reproducible method to induce LIM in mice using newly designed eyeglasses. The method fixes the lens stably in front of the mouse eye while allows the lens to be taken off for cleaning or topical drug administration. The phenotype is robust and efficient, and the variance is small. The method described here can be applied to mice right after weaning which extends the possible duration for experiments. We also gave technical advises for achieving reproducible results in refraction and axial length measurements. We hope the step-by-step protocol described here and the detailed article can help researchers perform myopia experiments with myopia more smoothly and make the data comparable across laboratories.

Introduction

The prevalence of myopia has increased dramatically recently, while the mechanism of its onset and progression are still largely unknow¹. The most characteristic phenotype of myopia is the elongation of axial length (AL), which increases risk for retinal complications or even blindness². To better understand the pathogenesis of myopia and develop effective treatments, robust myopic animal models and stable phenotype evaluation are necessary.

Briefly, two methods exist for inducing myopic states in animals: form-deprivation myopia (FDM) and lens-induced myopia (LIM)³. Th....

Protocol

All procedures were approved by the Ethics Committee on Animal Research of the Keio University School of Medicine adhered to the ARVO Statement for the Use of Animals in Ophthalmic and Vision Research, the Institutional Guidelines on Animal Experimentation at Keio University, and the Animal Research: Reporting of In Vivo Experiments (ARRIVE) guidelines for the use of animals in research.

1. Assembling the Eyeglasses for Mice

1. Prepare parts needed for assembling the eyeglasses (Figure 1a). For each mouse, prepare all followings: one head-mounted nylon stick, one higher and one lower titanium frame, tw....

Results

At first, check if all the necessary parts are prepared (Figure 1a). An example of a piece of assembled eyeglasses is shown in Figure 1b. Except for the main body of the frames and the nut, all other parts are disposable for each mouse. A set of completed eyeglasses is shown in Figure 1c. Change the angle between the two frames to fit the mouse with different ages.

Discussion

To make sure the eyeglasses to be fixed stably on the mouse head, several steps in this protocol need to be paid great attention. The periosteum must be removed completely before using the dental adhesive system. The blood on the skull also need to be cleaned up with care. While a little fine tuning is acceptable right after the application of the adhesive, do not move the stick frequently before the adhesive system dry up. Follow the instruction of the adhesive system carefully, especially the ratio of each component of.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
screw	NBK	SNZS-M1.4-10
washer	MonotaRO	42166397
nut	MonotaRO	42214243
stick	DMM Make	none	designed by authers and output by the 3D printer rented from DMM Make.
frame	DMM Make	none	designed by authers and output by the 3D printer rented from DMM Make.
lenses	RAINBOW CONTACT LENS	none	customized for mice use by the company
cyanoacrylate glue	OK MODEL	MP 20g
dental adhesive resin cement	SUN MEDICAL	super bond	contains the etching liquid used for removing the periosteum of the mouse skull
infrared photorefractor	Steinbeis Transfer Center	none	designed and offered by Dr. Frank Schaeffel from university of Tübingen
Spectral domain OCT	Leica	R4310
Tropicamide, Penylephrine Hydrochloride solution	Santen	Mydrin-P
midazolam	Sandoz K.K.	SANDOZ	components for the anesthetic
medetomidine	Orion Corporation	Domitor	components for the anesthetic
butorphanol tartrate	Meiji Seika Pharma	Vetorphale	components for the anesthetic
0.1 % purified sodium hyaluronate	Santen	Hyalein
atipamezole hydrochloride	Zenoaq	antisedan