What significant finding might be present in a patient with angle-closure glaucoma?

In a patient with angle-closure glaucoma, one of the hallmark signs is a fixed, dilated pupil. This occurs due to the increased intraocular pressure that accompanies the acute angle-closure event. When the angle between the iris and the cornea becomes narrowed or closed, this can lead to a sudden and severe rise in eye pressure, which affects the autonomic control of the pupil, resulting in it being unable to constrict properly in response to light. Thus, the fixed and dilated appearance of the pupil is a direct consequence of this pathophysiological process, making it a significant and distinguishing finding in patients experiencing angle-closure glaucoma.

In contrast, while tunnel vision, decreased visual acuity, and eye photophobia can occur in various eye conditions, they are not as specific or as immediately indicative of angle-closure glaucoma as the presence of a fixed, dilated pupil. Tunnel vision, typically related to peripheral field loss, and decreased visual acuity could result from prolonged increased intraocular pressure but do not directly reflect the acute state of the pupil. Photophobia can also occur due to several factors and is not a definitive sign of angle-closure glaucoma specifically.