Geometric isomerism (also known as cis-trans isomerism) is a form of stereoisomerism. This page explains what stereoisomers are and how you recognise the possibility of geometric isomers in a molecule. This lecture briefly describe types of isomerism: Structural isomerism; Stereoisomerism; Geometric isomerism and Optical isomerism. Geometric Isomerism occur where you have restricted rotation somewhere in a molecule. At an introductory level in organic chemistry, examples usually just involve the carbon-carbon double bond.