A Clinical Case from the Archives : 31/07/2005

This ocular appearance is seen on routine examation of a 14 year old mixed breed dog which the owners report as having no obvious visual deficit. What are you seeing here?

The dense white opacities in the anterior vitreous here are asteroid hylaosis. These bodies are hydroxylapatite consisting of calcium and phosphate according to Komatsu and colleagues (Fine structure and morphogenesis of asteroid hyalosis.
Med Electron Microsc. 2003 36:112-9) whileWinler and Lunsdorf (Ultrastructure and composition of asteroid bodies. Invest Ophthalmol Vis Sci. 2001 42:902-7)also note the importance of proteoglycans and hyaluronate in the vitreous in the biomineralisation process occurring in these older eyes. Moss and colleagues showed asteroid hylosis to be present in 1.2% of the aged human population in Beaver Dam, Wisconsin as shown here(Asteroid hyalosis in a population: the Beaver Dam eye study. Am J Ophthalmol. 2001 132:70-5) but we have, as yet, no idea of the prevalence in the older pet dog population.


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