You should be familiar with signs and symptoms of primary open angle glaucoma, including that around 40% of patients with glaucoma have IOP below 21mmHg.¹⁰⁴

Assessment of the central visual field may provide useful diagnostic information and complement the examination of the optic nerve head. Visual field findings should fit with optic disc findings. For example, if examination shows an inferior optic disc notch, you would expect to see a superior field defect. You should consider which visual field program is clinically indicated.

Visual field examination may sometimes produce anomalous results. However, you should not underestimate the usefulness of baseline measures and ongoing comparisons. Structural ocular imaging (such as an OCT) is not considered a robust substitute for a visual fields assessment. However, the complimentary use of functional (visual fields) and structural (OCT) assessments may help improve the sensitivity and specificity of detecting COAG. 

Patients with raised IOP are at increased risk of developing glaucoma. Where pressures are borderline, you should repeat the test, noting the time of day of each test. NICE recommends¹⁰⁵ that patients whose IOP by contact applanation tonometry is 24mmHg or higher should be:

1. formally diagnosed with ocular hypertension by a healthcare practitioner who has appropriate training or qualifications
2. treated, as they are at greater risk of developing glaucoma

SIGN recommends that patients with IOP >25mmHg may be considered for referral to the HES.

You should be aware of the signs and symptoms of other forms of glaucoma, such as acute or sub-acute narrow angle glaucoma or secondary glaucoma, due, for example, to pseudoexfoliation syndrome or pigment dispersion syndrome.