1 Guidance

The following guidance is based on the best available evidence. The full guideline ('Glaucoma: diagnosis and management of chronic open angle glaucoma and ocular hypertension') gives details of the methods and the evidence used to develop the guidance.

1.1 Diagnosis

1.1.1 At diagnosis offer all people who have COAG, who are suspected of having COAG or who have OHT all of the following tests:

  • IOP measurement using Goldmann applanation tonometry (slit lamp mounted)

  • central corneal thickness (CCT) measurement

  • peripheral anterior chamber configuration and depth assessments using gonioscopy

  • visual field measurement using standard automated perimetry (central thresholding test)

  • optic nerve assessment, with dilatation, using stereoscopic slit lamp biomicroscopy with fundus examination.

1.1.2 Adopt professional[2]/Department of Health[3] guidance to reduce the risk of transmitting infective agents via contact tonometry or gonioscopy.

1.1.3 Use Van Herick's peripheral anterior chamber depth assessment as an alternative to gonioscopy if clinical circumstances rule out gonioscopy (for example, when people with physical or learning disabilities are unable to participate in the examination).

1.1.4 Obtain an optic nerve head image at diagnosis for baseline documentation.

1.1.5 Ensure that all of the following are made available at each clinical episode to all healthcare professionals involved in a person's care:

  • records of all previous tests and images relevant to COAG and OHT assessment

  • records of past medical history which could affect drug choice

  • current systemic and topical medication

  • glaucoma medication record

  • drug allergies and intolerances.

1.1.6 Use alternative methods of assessment if clinical circumstances rule out the use of standard methods of assessment (for example, when people with physical or learning disabilities are unable to participate in the examination).

1.1.7 Ensure that all machines and measurement instruments are calibrated regularly according to the manufacturer's instructions.

1.2 Monitoring

1.2.1 Offer Goldmann applanation tonometry (slit lamp mounted) to all people with COAG, who are suspected of having COAG or who have OHT at each monitoring assessment.

1.2.2 Repeat CCT measurement as necessary (for example, following laser refractive surgery or at onset or progression of corneal pathology).

1.2.3 Offer Van Herick's peripheral anterior chamber depth assessment to all people with COAG, who are suspected of having COAG or who have OHT at each monitoring assessment.

1.2.4 Repeat gonioscopy when clinically indicated (for example, where a previous examination has been inconclusive or where there is suspicion of a change in clinical status of the anterior chamber angle).

1.2.5 Offer standard automated perimetry (central thresholding test) to all people who have established COAG and those suspected of having visual field defects who are being investigated for possible COAG. People with diagnosed OHT and those suspected of having COAG whose visual fields have previously been documented by standard automated perimetry as being normal may be monitored using supra-threshold perimetry (see tables 4 and 5 for recommended monitoring intervals).

1.2.6 Where a defect has previously been detected use the same visual field measurement strategy for each visual field test.

1.2.7 Offer stereoscopic slit lamp biomicroscopic examination of the optic nerve head to all people with COAG, who are suspected of having COAG or who have OHT at monitoring assessments (see tables 4 and 5 for recommended monitoring intervals).

1.2.8 When a change in optic nerve head status is detected by stereoscopic slit lamp biomicroscopic examination, obtain a new optic nerve head image for the person's records to provide a fresh benchmark for future assessments.

1.2.9 When an adequate view of the optic nerve head and surrounding area is unavailable at a monitoring visit, people undergoing stereoscopic slit lamp biomicroscopy should have their pupils dilated before the assessment.

1.2.10 Monitor at regular intervals people with OHT or suspected COAG recommended to receive medication (see recommendation 1.3.1), according to their risk of conversion to COAG (see table 4).

Table 4 Monitoring intervals for people with OHT or suspected COAG who are recommended to receive medication

Clinical assessment

Monitoring intervals (months)

IOP at target a

Risk of conversion to COAG b

Outcome c

IOP alone d

IOP, optic nerve head and visual field

Yes

Low

No change in treatment plan

Not applicable

12 to 24

Yes

High

No change in treatment plan

Not applicable

6 to 12

No

Low

Review target IOP or change treatment plan

1 to 4

6 to 12

No

High

Review target IOP or change treatment plan

1 to 4

4 to 6

a Person is treated and IOP is at or below target. If IOP cannot be adequately controlled medically, refer to consultant ophthalmologist.

b To be clinically judged in terms of age, IOP, CCT, appearance and size of optic nerve head.

c For change of treatment plan refer to treatment recommendations.

d For people started on treatment for the first time check IOP 1 to 4 months after start of medication.

1.2.11 Discuss the benefits and risks of stopping treatment with people with OHT or suspected COAG who have both:

  • a low risk of ever developing visual impairment within their lifetime

  • an acceptable IOP.

    If a person decides to stop treatment following discussion of the perceived risks of future conversion to COAG and sight loss, offer to assess their IOP in 1 to 4 months' time with further monitoring if considered clinically necessary.

1.2.12 In people with OHT or suspected COAG who are not recommended to receive medication, assess IOP, optic nerve head and visual field at the following intervals:

  • between 12 and 24 months if there is a low risk of conversion to COAG

  • between 6 and 12 months if there is a high risk of conversion to COAG.

    If no change in the parameters has been detected after 3 to 5 years (depending on perceived risk of conversion), or before if confirmed normal, the person should be discharged from active glaucoma care to community optometric care.

1.2.13 At discharge advise people who are not recommended for treatment and whose condition is considered stable to visit their primary care optometrist annually so that any future changes in their condition can be detected.

1.2.14 Monitor at regular intervals people with COAG according to their risk of progression to sight loss (see table 5).

Table 5 Monitoring intervals for people with COAG

Clinical assessment

Monitoring intervals (months)

IOP at target a

Progression b

Outcome c

IOP alone d

IOP, optic nerve head and visual field

Yes

Noe

No change in treatment plan

Not applicable

6 to 12

Yes

Yes

Review target IOP and change treatment plan

1 to 4

2 to 6

Yes

Uncertain

No change in treatment plan

Not applicable

2 to 6

No

Noe

Review target IOP or change treatment plan

1 to 4

6 to 12

No

Yes/uncertain

Change treatment plan

1 to 2

2 to 6

a IOP at or below target.

b Progression = increased optic nerve damage and/or visual field change confirmed by repeated test where clinically appropriate.

c For change of treatment plan refer to treatment recommendations.

d For people started on treatment for the first time check IOP 1 to 4 months after start of medication.

e No = not detected or not assessed if IOP check only following treatment change.

1.2.15 Following full recovery from surgery or laser trabeculoplasty, restart monitoring according to IOP, optic nerve head appearance and visual field (see table 5).

1.3 Treatment for people with OHT and suspected COAG

1.3.1 Offer people with OHT or suspected COAG with high IOP treatment based on estimated risk of conversion to COAG using IOP, CCT and age (see table 6).

Table 6 Treatment for people with OHT or suspected COAG

CCT

More than 590 micrometres

555–590 micrometres

Less than 555 micrometres

Any

Untreated IOP (mmHg)

> 21 to 25

> 25 to 32

> 21 to 25

> 25 to 32

> 21 to 25

> 25 to 32

> 32

Age (years)a

Any

Any

Any

Treat until 60

Treat until 65

Treat until 80

Any

Treatment

No treat-ment

No treat-ment

No treat-ment

BBb

PGA

PGA

PGA

a Treatment should not be routinely offered to people over the age threshold unless there are likely to be benefits from the treatment over an appropriate timescale. Once a person being treated for OHT reaches the age threshold for stopping treatment but has not developed COAG, healthcare professionals should discuss the option of stopping treatment.

The use of age thresholds is considered appropriate only where vision is currently normal (OHT with or without suspicion of COAG) and the treatment is purely preventative. Under such circumstances the threat to a person's sighted lifetime is considered negligible. In the event of COAG developing in such a person then treatment is recommended.

b If beta-blockers (BB) are contraindicated offer a prostaglandin analogue (PGA).

1.3.2 Do not treat people with suspected COAG and normal IOP.

1.3.3 Check that there are no relevant comorbidities or potential drug interactions before offering medication.

1.3.4 Offer alternative pharmacological treatment (a prostaglandin analogue, beta-blocker, carbonic anhydrase inhibitor or sympathomimetic) to people with OHT or suspected COAG and high IOP who are intolerant of the current medication.

1.3.5 Offer alternative pharmacological treatment (a prostaglandin analogue, beta-blocker, carbonic anhydrase inhibitor or sympathomimetic) to treated people with OHT or suspected COAG whose IOP cannot be reduced sufficiently to prevent the risk of progression to sight loss. More than one agent may be needed concurrently to achieve target IOP.

1.3.6 Refer treated people with OHT or suspected COAG whose IOP cannot be reduced sufficiently to prevent the risk of progression to sight loss to a consultant ophthalmologist to discuss other options.

1.3.7 Offer a preservative-free preparation to people with OHT or suspected COAG and an allergy to preservatives only if they are at high risk of conversion to COAG (IOP more than 25 and up to 32 mmHg and CCT less than 555 micrometres, or IOP more than 32 mmHg).

1.4 Treatment for people with COAG

1.4.1 Check that there are no relevant comorbidities or potential drug interactions before offering medication.

1.4.2 Offer people newly diagnosed with early or moderate COAG, and at risk of significant visual loss in their lifetime, treatment with a prostaglandin analogue.

1.4.3 Offer people with advanced COAG surgery with pharmacological augmentation (MMC or 5-FU)[4] as indicated. Offer them information on the risks and benefits associated with surgery.

1.4.4 Offer people who present with advanced COAG and who are listed for surgery interim treatment with a prostaglandin analogue.

1.4.5 Encourage people using the prescribed pharmacological treatment to continue with the same treatment unless:

  • their IOP cannot be reduced sufficiently to prevent the risk of progression to sight loss

  • there is progression of optic nerve head damage

  • there is progression of visual field defect

  • they are intolerant to the drug.

1.4.6 Check the person's adherence to their treatment and eye drop instillation technique in people with COAG whose IOP has not been reduced sufficiently to prevent the risk of progression to sight loss despite pharmacological treatment. If adherence and eye drop instillation technique are satisfactory offer one of the following:

  • alternative pharmacological treatment (a prostaglandin analogue, beta-blocker, carbonic anhydrase inhibitor or sympathomimetic); more than one agent may be needed concurrently to achieve target IOP

  • laser trabeculoplasty

  • surgery with pharmacological augmentation (MMC or 5-FU[4]) as indicated.

    If the pharmacological treatment option is chosen, after trying two alternative pharmacological treatments consider offering surgery with pharmacological augmentation (MMC or 5-FU[4]) as indicated or laser trabeculoplasty.

1.4.7 Offer surgery with pharmacological augmentation (MMC or 5-FU[4]) as indicated to people with COAG who are at risk of progressing to sight loss despite treatment. Offer them information on the risks and benefits associated with surgery.

1.4.8 Consider offering people with COAG who are intolerant to a prescribed medication:

  • alternative pharmacological treatment (a prostaglandin analogue, beta-blocker, carbonic anhydrase inhibitor or sympathomimetic) or

  • a preservative-free preparation if there is evidence that the person is allergic to the preservative.

    After trying two alternative pharmacological treatments consider offering surgery with pharmacological augmentation (MMC or 5‑FU[4]) as indicated or laser trabeculoplasty.

1.4.9 After surgery offer people with COAG whose IOP has not been reduced sufficiently to prevent the risk of progression to sight loss one of the following:

  • pharmacological treatment (a prostaglandin analogue, beta‑blocker, carbonic anhydrase inhibitor or sympathomimetic); more than one agent may be needed concurrently to achieve target IOP

  • further surgery

  • laser trabeculoplasty or cyclodiode laser treatment.

1.4.10 Offer people with COAG who prefer not to have surgery or who are not suitable for surgery:

  • pharmacological treatment (a prostaglandin analogue, beta‑blocker, carbonic anhydrase inhibitor or sympathomimetic); more than one agent may be needed concurrently to achieve target IOP

  • laser trabeculoplasty or cyclodiode laser treatment.

1.5 Organisation of care

1.5.1 Refer people with suspected optic nerve damage or repeatable visual field defect, or both, to a consultant ophthalmologist for consideration of a definitive diagnosis and formulation of a management plan.

1.5.2 Diagnosis of OHT and suspected COAG and formulation of a management plan should be made by a suitably trained healthcare professional with:

  • a specialist qualification (when not working under the supervision of a consultant ophthalmologist) and

  • relevant experience.

1.5.3 Healthcare professionals involved in the diagnosis of OHT and COAG suspect status and preliminary identification of COAG should be trained in case detection and referral refinement and be able to identify abnormalities based on relevant clinical tests and assessments. They should understand the principles of diagnosis of OHT and COAG and be able to perform and interpret all of the following:

  • medical and ocular history

  • differential diagnosis

  • Goldmann applanation tonometry (slit lamp mounted)

  • standard automated perimetry (central thresholding test)

  • central supra-threshold perimetry

  • stereoscopic slit lamp biomicroscopic examination of anterior segment

  • examination of the posterior segment using a slit lamp binocular indirect ophthalmoscopy

  • gonioscopy

  • Van Herick's peripheral anterior chamber depth assessment

  • CCT measurement.

1.5.4 People with a diagnosis of OHT, suspected COAG or COAG should be monitored and treated by a trained healthcare professional who has all of the following:

  • a specialist qualification (when not working under the supervision of a consultant ophthalmologist)

  • relevant experience

  • ability to detect a change in clinical status.

1.5.5 Healthcare professionals involved in the monitoring and treatment of people with OHT, suspected COAG and established COAG should be trained to make management decisions on all of the following:

  • risk factors for conversion to COAG

  • coexisting pathology

  • risk of sight loss

  • monitoring and clinical status change detection (for example, visual field changes, stereoscopic slit lamp biomicroscopic examination of anterior segment and posterior segment)

  • pharmacology of IOP-lowering medications

  • treatment changes for COAG, COAG suspect status and OHT (with consideration given to relevant contraindications and interactions).

1.5.6 People with a confirmed diagnosis of OHT or suspected COAG and who have an established management plan may be monitored (but not treated) by a suitably trained healthcare professional with knowledge of OHT and COAG, relevant experience and ability to detect a change in clinical status. The healthcare professional should be able to perform and interpret all of the following:

  • Goldmann applanation tonometry (slit lamp mounted)

  • standard automated perimetry (central thresholding test)

  • central supra-threshold perimetry (this visual field strategy may be used to monitor people with OHT or COAG suspect status when they have normal visual field)

  • stereoscopic slit lamp biomicroscopic examination of the anterior segment

  • Van Herick's peripheral anterior chamber depth assessment

  • examination of the posterior segment using slit lamp binocular indirect ophthalmoscopy.

1.5.7 Healthcare professionals who diagnose, treat or monitor people independently of consultant ophthalmologist supervision should take full responsibility for the care they provide.

1.6 Provision of information

1.6.1 Offer people the opportunity to discuss their diagnosis, prognosis and treatment, and provide them with relevant information in an accessible format at initial and subsequent visits. This may include information on the following:

  • their specific condition (OHT, suspected COAG and COAG), its life-long implications and their prognosis for retention of sight

  • that COAG in the early stages and OHT and suspected COAG are symptomless

  • that most people treated for COAG will not go blind

  • that once lost, sight cannot be recovered

  • that glaucoma can run in families and that family members may wish to be tested for the disease

  • the importance of the person's role in their own treatment – for example, the ongoing regular application of eye drops to preserve sight

  • the different types of treatment options, including mode of action, frequency and severity of side effects, and risks and benefits of treatment, so that people are able to be active in the decision-making process

  • how to apply eye drops, including technique (punctal occlusion and devices) and hygiene (storage)

  • the need for regular monitoring as specified by the healthcare professional

  • methods of investigation during assessment

  • how long each appointment is likely to take and whether the person will need any help to attend (for example, driving soon after pupil dilatation would be inadvisable)

  • support groups

  • compliance aids (such as dispensers) available from their GP or community pharmacist

  • Letter of Vision Impairment (LVI), Referral of Vision Impairment (RVI) and Certificate of Vision Impairment (CVI) registration

  • Driver and Vehicle Licensing Agency (DVLA) regulations.



[4] At the time of publication (April 2009), MMC and 5-FU did not have UK marketing authorisation for this indication. Informed consent should be obtained and documented. Both drugs should be handled with caution and in accordance with guidance issued by the Health and Safety Executive.

  • National Institute for Health and Care Excellence (NICE)