Effect of different fixative solutions on eyes with experimental proliferative vitreoretinopathy

Autor: S. Grisanti, Salvatore Grisanti, Mahmoud Ahmed Kamal, Matthias Lüke, Mahmoud Soliman, Khaled Nassar, Julia Lüke
Jazyk: angličtina
Rok vydání: 2015
Předmět:
Popis: Appropriate fixation of the eye is crucial for the evaluation of pathological changes such as retinal detachment (RD) in animal models. An ideal fixative should have a rapid penetration ability that can fix the delicate structures of the eye without disturbing the interfaces. Formaldehyde is a widely used, rapidly penetrating fixative. However, it takes at least a week to achieve full stabilization of histological structures. As well, whole eyes fixed in 4% buffered formaldehyde demonstrate a variety of artefacts, including separation of the neurosensory retina from the retinal pigment epithelium (RPE) (Kiernan 1999). Few chemicals have challenged the pre-eminence of 4% buffered formaldehyde as an ocular fixative. Among them is Bouin's fluid (BF), which is a mixture of different chemically active ingredients: picric acid, acetic acid and formaldehyde. However, the presence of picric acid in the fixative leads to safety hazards and disposal problems. Also, for an optimal fixation with BF, several alcohol rinses over two days are required and need to be followed by repeated incubation with an alcohol–lithium carbonate solution until the yellow colour of BF is depleted from the tissue (Cleary & Ryan 1979a,b; Latendresse et al. 2002). Another option for fixation was suggested by Yanoff and Fine: they found that a mixture of 2% buffered formaldehyde and 0.5% glutaraldehyde was superior to either fixative alone and gave acceptable results for both light and electron microscope (Yanoff & Fine 1967). Margo and Lee used enucleated eyes from dogs, rabbits and pigs that had been killed for non-ocular experiments to test the fixative effects. They recommended 1% formaldehyde plus 1.25% glutaraldehyde in phosphate buffer for immersion fixation of whole untreated eyes. They concluded that this solution causes a reduction in tissue distortion, thus preventing the separation of the neurosensory retina from the RPE (Margo & Lee 1995). In our study we wanted to find out the appropriate fixative for a standardized PVR (proliferative vitreoretinopathy) model in rabbit eyes. PVR is the most common reason for failure of retinal reattachment surgery and tractional retinal detachment after ocular trauma (Holekamp & Grand 1997; Colby 1999; Wang et al. 2007). Following penetrating trauma, PVR is estimated to occur in between 10 and 45% of eyes with a mean incidence of approximately 25% (Colby 1999; Wang et al. 2007). Therefore, PVR remains a problem despite advances in vitreoretinal surgery (Blumenkranz et al. 1982; Charteris et al. 2002; Sadaka & Giuliari 2012). For better understanding of the mechanisms and to evaluate therapeutic strategies against PVR, experimental models were developed (Agrawal et al. 2007). In the current study, we evaluate the use of 1% formaldehyde containing 1.25% glutaraldehyde compared to 4% formaldehyde as a fixative. Our goal was to improve the consistency of histopathological outcomes in a previously described rabbit model of PVR (Cleary & Ryan 1979a,b), in order to have a reliable base for further drug-testing experiments.
Databáze: OpenAIRE