Abstract
Abstract: :
Purpose:This study was performed to evaluate intraocular tolerance to perfluorohexyloctane (F6H8), a semi–fluorinated fluorocarbon of low specific gravity (1.35g/cm3) as a vitreous substitute in rabbits. Methods: Twelve eyes of pigmented adult rabbits underwent mechanical p.p.vitrectomy and vitreous replacement with F6H8 in nine eyes or balanced salt solution (BSS) in three eyes. The surgery was performed unilaterally, under anesthesia (ketamine and xylazine im). The eyes were examined by slit lamp biomicroscopy or indirect ophthalmoscopy every other day. Four animals, three of the F6H8 and one of the BSS group, were sacrificed as follows: 24 h, 7 d and 36 d postoperatively. The eyes were enucleated and processed for light and electron microscopy. Results:Clinical observations: The amount of inflammation in eyes receiving F6H8 was similar to that in control eyes (BSS) and usually subsided within 3 to 5 days. In the posterior chamber, dispersion was observed in the group of F6H8, early from the 6th day and was dense in the 36 days group. Some experimental eyes depicted few whitish precipitates in the vitreous cavity. Dispersion and precipitates did not affect the view to the fundus. Histopathologic observations: All the control eyes were free of pathological changes. In the F6H8 group, morphological alterations were found in the retina. On the 1st day, vacuolar changes were rarely observed in the inner retinal layer. On the 7th day vacuolar and myelinoid changes were frequently observed in the inner and outer retinal layer and rarely edema of the mitochondria of the ganglion cells. On the 36th day the changes were less prominent than the 7th day and the main findings were vacuolar, myelinoid changes and rare edema of the mitochondria of the Muller cells, in the inner retinal layer. The alterations were more prominent in the inferior retina. Histologic studies revealed no preretinal membrane formation, no up take of F6H8 and no nuclear drop–outs by the retinal cells adjacent to the vitreous cavity. The photoreceptor cells were normal. Conclusions:Our findings suggest that F6H8 is tolerated by the rabbit eye for 36 days since the alterations proved to be mild and quite reversible.
Keywords: microscopy: electron microscopy • pathology: experimental • vitreous substitutes