Intraocular pressure

Intraocular pressure is the fluid pressure inside the eye, maintained chiefly by the production and drainage of aqueous humor. It helps keep the eye’s shape but can damage the optic nerve when persistently elevated.

Aqueous humor: A clear fluid that fills the front chambers of the eye and supplies nutrients to the cornea and lens. Its production and drainage are the main determinants of intraocular pressure.
Tonometry: The measurement of intraocular pressure using instruments that assess the eye's resistance or deformation. It provides the routine clinical estimate of pressure.
Optic nerve: The bundle of retinal ganglion cell axons that carries visual information from the eye to the brain. Sustained pressure-related stress can damage its fibers.
Ocular hypertension treatment study: A clinical trial that tested whether treating ocular hypertension delays the onset of primary open-angle glaucoma. It established evidence for preventive pressure lowering in selected high-risk patients.
Ciliary body: A ring-shaped tissue behind the iris that produces aqueous humor and changes lens shape. Its ciliary processes continuously secrete the fluid that sustains pressure.
Goldmann applanation tonometry: A slit-lamp method that estimates intraocular pressure from the force needed to flatten a small area of cornea. It is a widely used reference method for measuring pressure.
Retinal ganglion cell: A retinal neuron whose axon forms part of the optic nerve and carries visual signals toward the brain. These cells are lost as glaucomatous damage progresses.
Primary open-angle glaucoma: A chronic optic neuropathy with an open drainage angle and progressive loss of retinal ganglion cells. It is the glaucoma subtype most closely associated with elevated intraocular pressure.
Trabecular meshwork: A porous tissue at the junction of the cornea and iris that drains aqueous humor from the eye. Resistance to outflow through this tissue can raise intraocular pressure.
Non-contact tonometry: A method of estimating intraocular pressure by directing a brief air pulse at the cornea. It measures pressure without touching the cornea, unlike applanation methods.

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