Final answer:
Glaucoma is the condition in which a high level of pressure in the eye, known as intraocular pressure, can lead to blindness. It occurs when fluid circulation is blocked, leading to increased pressure and possible optic nerve damage.
Step-by-step explanation:
The correct answer to the question is D. Glaucoma. Glaucoma is a condition caused by the buildup of fluid pressure in the eye, known as intraocular pressure. When the circulation of fluid in the eye is blocked, it leads to increased intraocular pressure, which can damage the optic nerve and potentially lead to blindness if left untreated. It is particularly important for people over 40 years of age to have their intraocular pressure tested regularly because they are at greater risk of developing glaucoma. Early detection and treatment are essential for controlling the condition and preventing permanent damage to eyesight.