Certified Emergency Nurse (CEN) Practice Test

The correct choice highlights a subjective symptom of glaucoma, which is characterized by the patient's personal experience of discomfort or pain. Sudden onset deep eye pain is a symptom reported by patients that suggests an acute change in their eye condition, such as high intraocular pressure or acute angle-closure glaucoma.

Subjective symptoms are those that cannot be measured directly by a healthcare provider but are described by patients regarding their feelings or perceptions. In this case, the deep eye pain is an experience only the patient can report, which is paramount in an emergency setting as it directs the clinician's attention toward potentially serious complications of glaucoma.

The other options represent objective findings or measurements. Foggy looking vision can be a symptom related to glaucoma but is often less immediately alarming than deep eye pain. A fixed pupil signifies a physiological change that can be assessed during an examination. Increased intraocular pressure (IOP) is measured via tonometry and indicates the disease's status but is not something the patient experiences subjectively. Thus, these options do not fall under the subjective symptom classification, confirming the correct response.