ciliar

Ciliar is an adjective used in anatomy to denote relation to cilia or to the ciliary body of the eye. In English, the more common form is ciliary, but ciliar appears in some medical texts and in several languages. The term derives from Latin ciliaris, related to cilium, meaning a hair or eyelash.

In ocular anatomy, ciliar refers to the ciliary body, a ring-shaped structure located behind the iris and forming part of the uvea. The ciliary body comprises the ciliary muscle and the ciliary processes. It produces aqueous humor, the fluid that fills the anterior segment of the eye, and, through the action of the ciliary muscle, controls accommodation by changing the lens’s shape via the suspensory ligaments (zonules). The ciliary processes also contribute to the secretion and dynamics of aqueous humor. The ciliary epithelium lines the inner surface of the ciliary body and participates in secretion and transport processes related to the production of ocular fluids.

Beyond the eye, the term can appear in histology to describe tissues or cells bearing cilia, i.e., ciliar or ciliated tissues. In practice, English usage tends to favor ciliary for these meanings, with ciliar appearing mainly in older texts or non-English sources.

Related terms include cilia, ciliary body, and ciliopathy (disorders related to ciliary function). In summary, ciliar denotes relationships to cilia or to the ciliary apparatus, most notably the eye’s ciliary body and its role in accommodation and intraocular fluid regulation.