Quantiﬁcation of Retinal Cells
A necessary milestone in establishing the safety and efﬁcacy of new neuroprotective interventions is histological evaluation of the retina in treatment and control groups. It is likely that any treatment will be quantitative in its effect-that is, that a disease process will be slowed rather than completely halted. This means that the evaluation will have be quantitative rather than qualitative in nature and will have to be designed to detect small but potentially signiﬁcant effects. The purpose of this chapter is to familiarize the reader with methods of counting cells in retinal whole mounts and sections. Examples will come from our work on photoreceptors and ganglion cells in human retina and the effects of aging and degeneration on these cell populations [1-6]. It should be emphasized that counting cell bodies is only the beginning of a complete evaluation of neural retina following treatments, because even modest loss could be accompanied by functionally signiﬁcant changes at the subcellular or synaptic level. This chapter does not address the methods required for such studies.