Model of retinal surface area and neuron distribution in the avian eye

Changes in retinal neuron distribution may reflect normal or pathological changes in retinal function. The quantitative study of retinal neurons provides a better understanding of anomalous mechanisms, such as those controlling ocular growth and refractive error development in experimental animals. We developed a method to facilitate the quantitative analysis of amacrine neuron populations in wholemount chick retinae, since the domestic chicken is used extensively as an animal model in myopia studies. This method involved automated cell counting from confocal microscopic images and mathematical estimation of total cell numbers based on image cell density and retinal surface areas. Cell densities and cell counts were obtained from immunohistochemically-labeled amacrine neuron populations, using derived formulae to calculate retinal surface area based on vitreous chamber depth, equatorial width, ora serrata diameter and scleral thickness. Normalized total cell counts in each eye were compared, rather than cell densities, since changes in eye growth can affect cell densities. We also compared neuron distribution in central versus peripheral portions of the retina. This is an alternative technique for retinal analysis that supplements traditional anatomical cell counting methods, allowing higher numbers of specimens to be rapidly analyzed.