Searching PubMed Using MeSH Search Tags
Untagged terms that are entered in the PubMed search box are automatically mapped to the MeSH vocabulary when a match is found. However, you may choose to search the MeSH headings specifically using search field tags (also called qualifiers).
MeSH headings [MH]
MeSH headings can be qualified using two search field tags:
[mh] to search a MeSH heading
[majr] to search a MeSH heading that is a major topic of an article
PubMed automatically searches the MeSH headings as well as the more specific terms beneath that heading in the MeSH hierarchy. This is known as the explosion feature.
eye [mh] will retrieve citations indexed to:
Anterior Eye Segment
Anterior Capsule of the Lens
Axial Length, Eye
Pigment Epithelium of Eye
Posterior Eye Segment
and all more specific terms underneath these in the hierarchy.
To turn off automatic explosion of MeSH headings, use one of the following tags:
[mh:noexp] or [majr:noexp]
This retrieves citations indexed with the term, Eye – but not necessarily indexed with the terms beneath that heading in the MeSH hierarchy. Remember that indexers use the most specific MeSH heading to describe the subject of a journal article.