In the context of the Captain Memo memory prosthesis for Alzheimer’s patients, we want to generate the family/entourage tree of the user from data structured based on the PersonLink ontology. This graph ought to be accessible and readable to this particular user. In our previous work, we proposed an ontology visualization tool called Memo Graph. It aims to offer an accessible visualization to Alzheimer’s patients. In this paper, we extend it to address the readability requirement based on the IKIEV approach. It extracts the most important instances (key-instances) from ontology and generates a “summary instance graph” (middle-out browsing method). The extraction and visualization processes are undertaken incrementally. First, an “initial summary instance graph” is generated, then permitting iteratively the visualization of supplementary key-instances as required. Key-instances’ extraction is based on measures that take into account the semantic similarity between the ontological elements and the user’s navigation history.