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Carlos Augusto Moreira, Pablo Zoroquiain, Christina Mastromonaco, Evangelina Esposito, Jacqueline Coblentz, Andre C Romano, Miguel N Burnier; Ocular clinical imaging and histopathological correlation: identifying the optimal fixation protocol. Invest. Ophthalmol. Vis. Sci. 2016;57(12):216.
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© ARVO (1962-2015); The Authors (2016-present)
There are many fixative solutions used in an ocular pathology laboratory; however, technical artifacts, such as artificial retinal detachment, are typically observed. The purpose of this study is to compare different fixative solutions in order to find the best fixation protocol that reduces retinal artifacts for further correlations with imaging studies.
Twenty-four rabbit eyes were enucleated 2 hours after euthanizing and were divided into 12 groups according to fixative solution and time (48 and 72 hours [h]). Embedding was performed in resin for eyes fixed in glutaraldehyde, while the remaining eyes were embedded in paraffin. The fixatives used included: formalin, glutaraldehyde, 37% formaldehyde, Davidson’s, and Zenker’s. Balanced saline solution (BSS) was used as a control. The following findings were recorded: shape of the globe (SG), transparency of the cornea (CT), lens (LT) and vitreous (VT), retinal nuclear details, area of retinal detachment (RD), sensory retinal thickness (RT), and nerve fiber layer thickness (NFL).
Davidson’s and 37% formaldehyde maintained SG in 100% of the cases. CT was maintained only in 12.5% and correspond to the BSS and 37% formaldehyde 48h groups. VT was maintained in 54% and correspond to Davidson’s, formalin and glutaraldehyde at both 48 and 72h. All eyes in the Davidson’s, formalin, glutaraldehyde, 37% formaldehyde groups had excellent nuclear detail resolution at both 48 and 72h. This was also seen in the 72h BSS group. The median area of RD was 191.1μm2 (range: 0-1632); the lowest and highest values were achieved by Davidson’s 48h (0μm2) and formalin 72h (1632μm2), respectively. The average of RT was 166μm (SD±37.59). The thinnest and the thickest sensory retina was seen with Zenker’s 72h (107.1μm) and 37% formaldehyde (235.05μm). The mean NFL thickness was 40μm (SD±23.32), while the thinnest and the thickest occurred with Zenker’s (8.08μm) and 37% formaldehyde (82.82μm) at 72h, respectively.
Davidson’s fixative method at 48h showed the most accurate anatomical representation of the retina. The eyes fixed with Davidson’s maintained a transparent vitreous and the sensory retina remained in place. Davidson’s also preserved retinal and NFL thickness. Although cornea and lens opacification occurred with this protocol, these structures can be removed for retinal imaging histopathological correlation studies.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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