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Knowledge, skills and performance

Examining patients at risk from glaucoma

Key points

You must carry out relevant tests when examining a patient who is in an at-risk group for glaucoma.
Those with a greater than average risk include certain ethnic groups, patients with first degree relatives with glaucoma and those over 40.
In England, patients whose IOP is 24mmHg or greater should be treated.
You should follow local protocols if you are participating in community services.

A251

This Guidance does not change what you must do under the law.

Principles of examining patients at risk from glaucoma

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When examining a patient who is in an at-risk group for glaucoma, you must carry out relevant tests.⁹⁹ Guidance varies across the UK.^{100, 101, 102} You should be familiar with the relevant guidance and the thresholds at which further tests should be undertaken. If local protocols apply you should comply with these.

A253

Glaucoma can be difficult to detect in the early stages and you should stay up to date with current thinking on the pathophysiology, clinical signs and diagnostic techniques required to detect it.

References

⁹⁹ Sight Testing (Examination and Prescription)(No 2) Regulations 1989 para 26(1)(a) [Accessed 1 Nov 2023]
¹⁰⁰ National Institute for Health and Care Excellence (2017) Glaucoma: diagnosis and management [Accessed 31 Jul 2023]
¹⁰¹ The College of Optometrists (2017), NICE Guideline – Glaucoma diagnosis and management (update) [Accessed 1 Nov 2023]
¹⁰² Scottish Intercollegiate Guidelines Network (2015) Glaucoma Referral and Safe Discharge [Accessed 1 Nov 2023]

Identifying patients at risk from glaucoma

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You will identify the majority of patients who are at risk from chronic open angle glaucoma during a routine eye examination. They are principally patients with one or more of the following:

optic disc features suggestive of glaucoma
loss of peripheral vision
high IOP.

A255

Even in the absence of the signs or symptoms in the paragraph above, patients at greater than average risk of primary open angle glaucoma include those:¹⁰³

in certain ethnic groups, for example African-Caribbean people
with first degree relatives with glaucoma
over the age of 40. The risk increases with every decade of life thereafter
with thinner corneas
with myopia (myopia >6D is associated with an increased risk)
with diabetes
with systemic hypertension
taking topical or systemic steroids, as they may develop steroid-induced glaucoma.

A256

The signs of asymptomatic chronic angle closure glaucoma are almost identical to those of chronic open angle glaucoma with the exception that the anterior chamber angle is capable of intermittent closure or being obstructed.

A257

The prevalence of angle closure glaucoma is greater than that of chronic open angle glaucoma (COAG) in people of South or East Asian descent.

References

¹⁰³ The College of Optometrists (2018) Clinical Management Guidelines Primary Open Angle Glaucoma [Accessed 1 Nov 2023]

Diagnostic information

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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

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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.

A260

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.

A261

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:

formally diagnosed with ocular hypertension by a healthcare practitioner who has appropriate training or qualifications
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.

A262

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.

References

¹⁰⁴ Shah R, Wormald R (2011) Glaucoma. BMJ Clinical Evidence (online) [Accessed 1 Nov 2023]
¹⁰⁵ National Institute for Health and Care Excellence (2017) Glaucoma: diagnosis and management NG81 [Accessed 1 Nov 2023]

Procedures to include in an examination in routine practice

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You should select additional procedures to those in the routine eye examination, according to the patient’s clinical need. You should normally:

assess the optic nerve head. This would include assessing the size of the disc
measure the IOP. See section on the use of non-contact tonometry.

A264

If a patient refuses to consent to tonometry after you have explained the reason for this procedure, you should record the patient’s reason for refusal. You should use your professional judgement to decide how best to manage the patient.

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The examination may also include an assessment of the central visual field using perimetry with threshold control. Where necessary, you should repeat visual field assessment to obtain a meaningful result.

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If the patient is at risk from glaucoma, you should assess the anterior eye and angle, for example by slit lamp – Van Herick technique. You should also look for signs of pigment dispersion syndrome (PDS) and pseudoexfoliation (PEX).

A267

Optic nerve head imaging, including photography and OCT, may be helpful for the assessment and detection of abnormal structural changes to the optic nerve head. You should stay up to date with the evidence and be cautious about management decisions based on imaging alone.

A268

You should follow local protocols and referral filtering pathways for people presenting with ocular hypertension or evidence of glaucoma.

Use of non-contact tonometry (NCT)

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It is good practice to follow up equivocal results from non-contact tonometry with contact applanation tonometry. If you are using non-contact tonometry, before considering referral you should take four readings per eye. In England, Wales and Northern Ireland, in the absence of other signs of glaucoma, you should refer the patient for further assessment only when the mean of the IOP readings is 24mmHg or above. You should advise people with IOP below 24mmHg to continue with their routine eye examinations. In Scotland you should follow SIGN guidelines.

Referral and organisation of care

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In England, unless clinical circumstances indicate that urgent or emergency referral is indicated, patients should have referral filtering before they are referred to the HES. For these non-urgent patients, you should only refer without referral filtering if there are no such local arrangements. Referral filtering is where the patient has additional tests done. These may be repeat measures, referral refinement or enhanced case finding.¹⁰⁶ In Scotland you should follow SIGN guidelines.