Glaucoma - Chronic Open Angle

Question 1

Aetiology

Answer 1

COAG is progressive optic neuropathy with loss of retinal ganglion cells and their axons.
The AC is open and there is no secondary cause for nerve damage e.g. steroid glaucoma, pigment dispersion, pseudoexfoliative glaucoma

Question 2

Predisposing factors

Answer 2

Age
Afro-Caribbean descent
FHx of G
Myopia
Diabetes
Raynauds / Low BP
OHT

Question 3

Symptoms

Answer 3

Asymptomatic unless significant VF loss (advanced cases)

Question 4

Signs

Answer 4

Optic nerve
- Assess cup to disc ratio in relation to disc size.
- Disc asymmetry
- >0.60 cupping in average or small discs
- Diffuse NRR loss, focal thinning, focal notching
- DDLS grading. Refer Grade 4 or more.
- Disc margin haemorrhage
- Wedge shaped RNFL loss
- OCT imaging to allow for progressive change monitoring

Visual field
- Repeatable VF defect
- Arcuate defect, nasal step, paracentral loss, temporal wedge

Tonometry
- Modifiable risk factor.
- A lot of Pxs with COAG have normal IOPs
- Measure CCT as thick corneas can over estimate IOP, thin corneas underestimate.
- Repeat measurements in the morning as IOP tends to be higher - diurnal variation >4mmHg

Gonioscopy
- Shaffers grade 3 or 4

Slit lamp examination
- AC VH G3 or G4.

Question 5

Non-pharmacological management

Answer 5

Routine referral in presence of disc damage with repeatable visual field defect for definitive diagnosis and management plan creation

Give Px’s relevant information and booklets - allow for them to ask more about their diagnosis e.g. prognosis, management, treatment.

New Pxs with OAG are being offered first line 360 SLT (unless they have PDS) which is clinically effective and cost-effective when compared to topical hypotensive drugs.

Question 6

Pharmacological management

Answer 6

Do not commence treatment until definitive diagnosis from consultant has been given. In some cases, collaboration with Glaucoma service, IP with special Glaucoma certification can prescribe drugs for those who are awaiting SLT.

Question 7

Management at HES

Answer 7

Confirm diagnosis.
Individual management plan
Reduce IOP by considering the following:
- Target IOP
- Compliance - simpler the better
- Side effects, contraindications, drug interactions
- Patient’s needs and preferences

First line treatment is PROSTAGLANDIN ANALOGUES, then beta-blockers (more systemic effects), then CAI/alpha agonists.
Rarely oral CAI required but some cases warrant this.

More Px’s are being offered SLT as first line treatment.
Trabeculectomy offered in more advanced cases.
Some Px’s undergoing cataract surgery may get MIGS with it too.