What does intraocular pressure (IOP) measure?

Intraocular pressure (IOP) specifically measures the fluid pressure inside the eye. This pressure is critical for maintaining the eye's shape, ensuring that it functions properly, and facilitating the flow of nutrients and waste across eye structures. The measurement of IOP is vital in diagnosing and monitoring glaucoma and other ocular conditions since an increase in IOP can lead to optic nerve damage and vision loss. By measuring IOP, healthcare providers can assess the risk of these conditions and implement appropriate management strategies. The other choices, while related to eye health, do not accurately reflect what IOP measures. For instance, the thickness of the lens, vision acuity, and corneal sensitivity are distinct parameters that pertain to different aspects of visual function and anatomy, rather than the pressure within the eyeball itself.