Comparison of rabbit retinal fixation techniques: chemical fixation and microwave irradiation / 中华实验眼科杂志

ABSTRACT

Background Conventional chemical method to fix the entire eyeball results in the edema of retinal nerve fiber layer and therefore influent the evaluation of tissue structure.Research showed that microwave irradiation can avoid this phenomenon. Objective This study was to investigate the appropriate energy and time duration of microwave irradiation for fixation of rabbit eyes specimen and compare the influence of different fixation methods on retinal structure. Methods Twenty-two New Zealand white rabbits were sacrificed by using venous air embolism.The eyeballs were enucleated from the rabbits and immersed in chemical reagents with glacial acetic acid,methyl aldehyde and chloroform for 2 days as the control group.The eyeballs were immersed in 400 ml physiological balance solution immediately,and then were fixed by microwave irradiation for 80,160,240 and 320 seconds under the lower power as the microwave irradiation groups.In the microwave irradiation+chemical fixation group,the specimens were immersed in chemical reagents for 1-2 hours after the microwave radiation.The morphology of retinal structure was examined and area of retinal detachment was calculated by hemotoxylin and eosin staining under the light microscope. Results A better fixation effect was obtained in the retinal section of microwave radiation for 240 seconds in comparison with that of the traditional chemical reagent fixation method for 2 days.The retina detachment ratio was 16.3%±11.5% for simple microwave method,50.0%±24.5% for chemical method,and 6.7%±7.8% for microwave+chemical method.showing a significant difference among 3 groups(F=32.43,P=0.000).Retinal staining was clear and retinal structure was almost normal in the specimens of microwave+chemical fixation group with 200-240 seeonds microwave irradiation and 1-2 hours chemical fixation. Conclusion Microwave irradiation method is a more ideal way for the fixation of retina because of taking short duration,lower toxicity and better staining.The combination of microwave radiation and chemical reagents can acquire an excellent quality of retinal section.