Final answer:
The disorder characterized by excessive intraocular pressure due to improper drainage of the aqueous humor is glaucoma.
Step-by-step explanation:
The disorder that involves excessive intraocular pressure, caused by a failure of the aqueous humor to drain properly, is glaucoma. The eye pressure maintained by the aqueous humor is essential to keep the shape of the eye. When there is a blockage and the fluid can't circulate properly, it can lead to increased pressure, known as glaucoma. This condition can be especially risky for people over 40 years of age, who should have their intraocular pressure tested routinely to detect and possibly control the condition.