Abstract:  Objective To investigate the characteristics, similarities and differences of the histopathological examination (paraffin and frozen sections) and the spectral domain high-resolution optical coherence tomography(HD-OCT) used for evaluation of rat retinal sublayers. Design Experimental study. Participants Twelve healthy Brown Norway (BN) rats. Methods The Cirrus HD-OCT was used to evaluate the thickness of the retinal sublayers of all the eyes in a peripapillary distribution at a distance about 2 disc diameters. The left eyes from the rats were made into paraffin sections and the right eyes were made into frozen sections after rats were sacrificed. The thickness of rat retinal sublayer approximately 2 optic disc diameters away from the optic disc were measured. The data were statistically analyzed. Main Outcome Measures The thickness and morphological characteristics of rat retinal sublayer. Results  The thickness of BN rat retina was (166.98 ± 9.07）μm that measured in paraffin sections, (209.06 ± 10.41）μm in frozen sections, and (208.75 ± 11.19）μm in the OCT images, respectively. The thickness of the retina measured in the frozen sections was similar to that measured in the OCT images, and there was no significant difference statistically(P=0.425). The significant difference was found between paraffin sections and the other two groups (P <0.001). Except the thickness of inner nuclear layer, the thickness of other sublayers was significantly different among the three groups(P <0.05). The thickness of the rat retinal sublayer in paraffin sections was perceptibly less, but the organizational structure was more complete and clearer, and it showed more clearly at the cellular level. The rat retina images can be obtained by the spectral domain HD-OCT, but the boundaries between sublayers were not clear in some sublayers. The examination of frozen section was convenient and quickly, and the results were consistent with that measured in the OCT images. But it was likely to induce the incompletion of retinal nerve fiber layer caused by posterior detachment of vitreous. Conclusion Each method has its own unique characteristics on evaluation of rat retinal sublayer, but also some consistency. When conducting retinal quantitative study, frozen sections and OCT images are more accurate. When making qualitative research, the paraffin sections of tissue morphology is clearer and more complete, especially when focusing on cellular level. (Ophthalmol CHN, 2013, 22: 344-348)

Key words: retina, histopathology, optical coherence tomography, animal, laboratory