Which sign is NOT typically associated with an acute PACG attack?

The correct answer highlights that normal intraocular pressure is not typically associated with an acute attack of primary angle-closure glaucoma (PACG). During an acute PACG attack, there is a sudden and significant increase in intraocular pressure due to the blockage of the aqueous humor outflow. This occurs when the drainage angle formed by the cornea and the iris becomes closed, preventing fluid from leaving the eye, leading to elevated intraocular pressure.

In contrast, the other signs listed—such as a fixed, semi-dilated pupil, corneal opacity, and dilated limbal and conjunctival vessels—are commonly seen during an acute PACG attack. The fixed and semi-dilated pupil indicates that the iris is reacting to the intraocular pressure changes. Corneal opacity may occur as the cornea becomes edematous from the high pressure, and dilated vessels may reflect the eye's inflammatory responses that accompany this type of acute condition. Therefore, normal intraocular pressure would be incongruent with the expected signs of an acute PACG attack, making it the correct choice.