Polymerase chain reaction (PCR) is an important technique used in numerous basic studies involving DNA molecules. It works by amplifying specific DNA sequences using primers and DNA polymerase. Glypican-3 (GPC3) is highly expressed in hepatocellular carcinoma cells and tissues and may play an important role in cancer progression by interacting with matrix metalloproteinases and growth factors. Real-time PCR can detect eye pathogens like bacteria and fungi within two hours, much faster than traditional culture methods which take 48 hours, though PCR risks false positives. PCR has many medical uses including disease diagnosis, genetic screening, detection of infectious organisms, and characterization for transplants.