With proliferation of publications on ontology-based e-learning systems (OBELS) ontology has become an important component that underpins the enhancement of e-learning systems. E-learning systems proposed in published articles have deployed ontologies to specify and deal with different aspects of e-learning, from e-learning content design to assessment. This review paper aims at finding answers to the questions: What types of ontologies are used in e-learning systems? What are the current issues in e-learning? How ontologies have been used as solutions to them? What are the gaps and limitations in OBELS research? A Systematic Literature Survey (SLS) is conducted on published scholarly work available in several popular electronic library databases. Articles related to the research have been collected using automated and manual search techniques. This paper provides an analysis of the 22 Q1 journal articles that were short listed from 154 articles as well as answers to the research questions. A large number of articles predominantly discuss about ontologies used in their work to overcome issues in e-learning. Based on this review of articles four main types of ontologies are identified: domain ontology, course ontology, educational resources ontology and user ontology. Besides that, this study identifies some key issues in e-learning and how ontology has become a solution to them.