Andrology Lab Corner*: Reflections on CASA After 25 Years

Abstract

Like the Journal of Andrology, computer assisted sperm analysis (CASA) systems did not arise de novo. Although both are celebrating 25th anniversaries, the Journal evolved over several years and drew on predecessors. In contrast, today's CASA systems represent third-genera-tion devices for visualization and analysis of sperm mo-tion. Modern CASA evolved some 300 years after the first-generation device was placed into use. This device was the light microscope, which von Leeuwenhoek used to first visualize sperm in 1678. The concept and princi-ples underlying such a device did not change until shortly before World War II, when European opticians developed phase-contrast optics. Such second-generation devices were first used by pioneering andrology labs in the mid-1950s, and phase-contrast microscopes remain the pri-mary instruments for observation of living sperm. Phase-contrast optics are integral to every contemporary CASA system because they enable high-contrast visualization and edge detection of each translucent cell. Important publications on quantifying sperm motion appeared between 1940 and 1970 (summarized by Boyers et al, 1989), and provided a foundation for CASA sys-tems. However, the approaches in these studies were not at all automatic, and most used manual cartography. By the early 1970s, convergence of technology and govern-ment priorities set the stage for development of CASA. Federal and private investments in tracking rockets and diverse objects on the macroscale increased significantly. to improve exponentially. Video cassettes replaced the original reel-to-reel technology. As a result, computerized video image digitization, recognition, and quantification technologies began to emerge, with substantial cost sav-ings over prior methodologies. Applications to the micro-scope followed and primitive CASA systems emerged. Here we consider the motives of individuals and com-panies pioneering CASA, and comment upon whether their expectations were realistic (with the benefit of hind-sight) and met. We note the positive and negative impacts of CASA in sperm biology, clinical medicine, and epi-demiology. We also reflect on the role of high-technology devices in the practice of andrology. We restrict our con-siderations to measurement of sperm motion, although current CASA systems can measure number of sperm per unit volume and can be modified to capture data appro-priate for morphologic classification of each sperm ex-amined.