Vitreous

The vitreous, or vitreous humor, is the clear gel that fills the vitreous cavity of the eye. It occupies about 4 mL in an adult and accounts for roughly four‑fifths of the eye’s volume. The vitreous is optically transparent, helping to transmit light to the retina while maintaining the globe’s shape and providing a stable, low‑motion medium for retinal images.

Structurally, the vitreous is a gel composed mainly of water (about 98–99%), with a collagen fiber network embedded in a hyaluronic acid–rich matrix. This framework forms a peripheral cortex and a clearer central core. The vitreous is largely avascular and is separated from the retina by the posterior hyaloid membrane. It is firmly attached at the vitreous base near the ora serrata, around the macula, along retinal vessels, and at the optic disc, with attachments that tend to strengthen with age. During life, the gel slowly liquefies (syneresis), and a posterior vitreous detachment may occur in many individuals.

Clinically, the vitreous can influence vision through floaters or flashes of light when vitreous material or traction interacts with the retina. Age‑related changes or traction from detachments can lead to retinal tears or detachment. Inflammation of the vitreous is termed vitritis or intermediate uveitis and can accompany systemic conditions. Other conditions include vitreous hemorrhage or sequestration of inflammatory cells.

Diagnosis relies on ophthalmic examination using slit lamp and indirect ophthalmoscopy, with adjunct imaging such as ultrasound B‑scan or OCT when needed. Treatments range from observation for benign changes to surgical intervention, notably pars plana vitrectomy, for conditions like macular holes, retinal detachments, or nonresolving vitreous hemorrhage. In surgery, vitreous substitutes (gases or silicone oil) may be used to support the retina during healing.