case finding and diagnosis of chronic open angle glaucoma (COAG)
Last edited 02/2022 and last reviewed 06/2022
Case finding in chronic open angle glaucoma (COAG)
Before referral for further investigation and diagnosis of COAG, offer all of the following tests:
central visual field assessment using standard automated perimetry (full threshold or supra-threshold)
optic nerve assessment and fundus examination using stereoscopic slit lamp biomicroscopy (with pupil dilatation if necessary), and optical coherence tomography (OCT) or optic nerve head image if available
intraocular pressure (IOP) measurement using Goldmann-type applanation tonometry
peripheral anterior chamber configuration and depth assessments using gonioscopy or, if not available or the person prefers, the van Herick test or OCT.
Do not base a decision to refer solely on IOP measurement using non-contact tonometry.
Refer for further investigation and diagnosis of COAG and related conditions, after considering repeat measures ** if:
there is optic nerve head damage on stereoscopic slit lamp biomicroscopy or
there is a visual field defect consistent with glaucoma or
IOP is 24 mmHg or more using Goldmann-type applanation tonometry
**Before deciding to refer, consider repeating visual field assessment and IOP measurement on another occasion to confirm a visual field defect or IOP of 24 mmHg or more, unless clinical circumstances indicate urgent or emergency referral is needed
Advise people with IOP below 24 mmHg to continue regular visits to their primary eye care professional.
Diagnosis of chronic open angle glaucoma (COAG)
Offer all of the following tests:
- visual field assessment using standard automated perimetry (central thresholding test), repeated if necessary to establish severity at diagnosis
optic nerve assessment and fundus examination using stereoscopic slit lamp biomicroscopy, with pupil dilatation
IOP measurement using Goldmann applanation tonometry (slit lamp mounted)
peripheral anterior chamber configuration and depth assessments using gonioscopy
- central corneal thickness (CCT) measurement
Use the van Herick peripheral anterior chamber depth assessment if clinical circumstances rule out gonioscopy (for example, when people with physical or learning disabilities are unable to participate in the examination).
Obtain an optic nerve head image at diagnosis for baseline documentation (for example, a stereoscopic optic nerve head image or OCT).
After referral, consider an early assessment appointment if there is clinical concern based on the information provided.
At the time of diagnosis of ocular hypertension (OHT), assess the risk of future visual impairment taking into account risk factors such as
level of IOP