Ketamine-xylazine anesthesia causes hyperopic refractive shift in mice

Area of Science:

• Ophthalmology
• Animal Models
• Vision Science

Background:

• Mice are crucial models for myopia research, requiring precise refractive error assessment.
• Accurate refractive measurements in mice necessitate immobilization and control of physiological factors.
• The impact of common anesthetic and mydriatic agents on mouse eye refraction remains largely uninvestigated.

Purpose of the Study:

• To evaluate the effects of tropicamide and ketamine-xylazine anesthesia on refractive status in mice.
• To explore alternative immobilization methods for accurate refractive error measurement in mice.
• To guide best practices for refractive error assessment in mouse models of myopia.

Main Methods:

• Refractive error assessment in P40 C57BL/6J mice under different conditions.
• Comparison of tropicamide eye drops, ketamine-xylazine anesthesia, pentobarbital anesthesia, and a restraining platform.
• Statistical analysis of refractive shifts induced by each method.

Main Results:

• Tropicamide induced a minor but significant hyperopic shift.
• Ketamine-xylazine anesthesia caused a substantial and significant hyperopic shift.
• Pentobarbital anesthesia had minimal effect; restraining platforms proved effective for immobilization.

Conclusions:

• Ketamine-xylazine anesthesia significantly confounds refractive error measurements in mice and should be avoided.
• Tropicamide causes a small refractive shift, requiring consideration in experimental design.
• Restraining platforms are a viable alternative for mouse immobilization in refractive studies.
• Standardized experimental conditions are essential for reliable myopia research in mice.