Early changes in vision due to open-angle glaucoma involves a loss of peripheral vision at first, while visual acuity (e.g., central vision) is maintained until later in the course of the disease. For this reason, open-angle glaucoma progresses relatively asymptomatically, and patients often do not present with symptoms or visual complaints until late in the course of the disease.

Clinical suspicion should, therefore, be high in the following patients who have or have had:

• A previous ocular history such as history of eye pain or redness, headaches, uveitis, diabetic retinopathy, cataracts, vascular occlusions, or multicolored halos
• Ocular surgery like photocoagulation or refractive procedures such as laser eye surgery)
• Head or ocular trauma
• Take certain medications such as hypertensive medications that may influence IOP or systemic/topical steroids
• Medical history of diabetes mellitus, migraine headaches, hypertension, vasospasm, cardiovascular disease
• Family history (e.g., first-degree relative with glaucoma, especially significant if this is a sibling) that would place them at a greater risk of developing open-angle glaucoma.