Glaucoma or not glaucoma that is the question

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Glaucoma or not glaucoma – that is the question

Dr Jack Phu

BOptom (Hons), BSc, MPH, PhD, FAAO, Diplomate (Glaucoma)

Head, Glaucoma/Neuro-ophthalmology, Centre for Eye Health

Lecturer, School of Optometry and Vision Science, UNSW

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Learning objectives

1. Be able to recognise non-glaucomatous visual field defects and action

relevant further investigations

2. Apply multimodal imaging techniques to distinguish glaucoma and

non-glaucomatous optic atrophy

3. Understand the limitations of cross-sectional optical coherence tomography

parameters in glaucoma diagnosis

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“Typical” glaucoma

Key feature: structure-function concordance at the optic nerve head

Other clinical features

IOP 25 mmHg

CCT 510 microns

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What is the definition of glaucoma?

Casson et al 2012 CEO

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What is the definition of glaucoma?

Casson et al 2012 CEO

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Glaucomatous visual field defects

Which of these are/is a “typical” glaucomatous visual field defect?

Highlight issues with visual fields

- Pattern

- Depth

- Structure-function

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Glaucomatous vs non-glaucomatous visual field loss

▪ Check and describe the pattern of visual field loss (often useful to “say” it in

words)

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Case #2 – is this glaucoma? – 72 year old Asian female

Medical history:

• Diabetes (5 years)

• Hypertension

• Hyperlipidaemia

Ocular history:

• Unremarkable cataract surgery

• Currently on Xalatan nocte

Clinical findings

• Vision normal

• IOP 15 mmHg

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Case #2 – is this glaucoma? – 72 year old Asian female

Medical history:

• Diabetes (5 years)

• Hypertension

• Hyperlipidaemia

Ocular history:

• Unremarkable cataract surgery

• Currently on Xalatan nocte

Clinical findings

• Vision normal

• IOP 15 mmHg

• Pachymetry 552 microns

“Cupping” and retinal nerve fibre layer

defect present – contiguous to the disc

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Case #2 – is this glaucoma? – 72 year old Asian female

Poll: Structure-function correlation – is this

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Case #2 – is this glaucoma? – 72 year old Asian female

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Features not typical of glaucoma?

Optic nerve scan typical

pattern (arcuate)

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Features not typical of glaucoma?

Optic nerve scan typical

pattern (arcuate)

However, macula

scan NOT typical

Incomplete arcuate…

loss is too focal

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Features not typical of glaucoma?

Note the attenuation of

retinal arteries and the

presence of an arterial ghost

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Features not typical of glaucoma?

OCT-A visualises loss of

retinal perfusion and

attenuation of vessel

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Vascular loss in glaucoma

▪ Current prevailing hypothesis: significant drop out of vasculature occurs

following neural loss – deep OCT angiography loss NOT suggestive of

glaucoma in the first instance

▪ Clinical data suggests greater dynamic range in advanced glaucoma

(Yarmohammadi et al 2016 IOVS; Moghimi et al 2019 Ophthalmology)

▪ Glaucoma is a primary loss of neural tissue – other vascular losses (e.g.

occlusive disease) lead to consecutive optic atrophy

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Glaucoma as a chronic optic neuropathy

▪ Acute, episodic events upon the optic nerve cause acute, episodic

changes, but not chronic changes expected in glaucoma

– Acute, episodic increases in intraocular pressure

(Garala & Bansal, 2019 J Glaucoma)

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Glaucoma as a chronic optic neuropathy

▪ Acute, episodic events upon the optic nerve cause acute, episodic

changes, but not chronic changes expected in glaucoma

– Acute, episodic increases in intraocular pressure

(Garala & Bansal, 2019 J Glaucoma)

– Acute vascular insufficiencies – haemodynamic crisis

(Broadway & Drance, 1998)

▪ Glaucoma more related to chronic changes, examples:

– Chronic elevated intraocular pressure

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Case #3 – is this glaucoma? 58 year old Caucasian male

Clinical findings

• IOP 10-13 mmHg

• Pachymetry 550 microns

• No systemic disease

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Case #3 – is this glaucoma? 58 year old Caucasian male

Clinical findings

• IOP 10-13 mmHg

• Pachymetry 550 microns

• No systemic disease

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Case #3 – is this glaucoma? 58 year old Caucasian male

Clinical findings

• IOP 10-13 mmHg

• Pachymetry 550 microns

• No systemic disease

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Poll: is this glaucoma – yes/no?

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Extra testing – intraocular pressure profiling

▪ Both water drinking

test and pressure

phasing

(Susanna Jr et al 2017

CEO; Huang et al 2018 OVS,

Huang et al 2020 OVS)

▪ This will also help to

guide treatment

modality

(Gazzard et al 2019

Lancet)

Water drinking test: unchanged

(no higher than 14.5 mmHg)

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Intraocular pressure profiling

▪ Analogous to other medical stress

tests

(Susanna et al 2018 J Glaucoma)

▪ A measurement of trabecular

outflow facility

– Relevance at diagnosis and in

treatment (therapy should control

fluctuations)

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Extra testing – OCT angiography

Again… deep

vascular loss – not

typical of glaucoma

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Glaucoma as a diagnosis of exclusion

▪ Glaucoma defined as a disease of the optic nerve

head – needs to have visible changes

▪ Glaucoma defined as a progressive optic

neuropathy

▪ Risk factors: elevated, fluctuating pressures

▪ Neural loss typically precedes deep vascular loss

Therefore, management plan is

review until progression

established

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Follow up appointments

▪ Three month follow up

▪ No changes to history or symptoms

▪ MD/PSD results: unchanged

How would you describe this

visual field result relative to

baseline?

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Follow up appointments

What kind of pattern of disease progression do we expect if it was

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Case #6 – 61 year old South Asian male

▪ Referred for opinion regarding superior visual field defects and suspicious

cupping

▪ MHx: hyperlipidaemia – treated

▪ Other history: non-contributory

OD

OS

Vision (mild myopia)

6/6

Pressures

15

13 Pachymetry

576

569

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Clinical data

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Longitudinal data

No significant structural change (just due to

floaters)

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No change in visual field defect (some

improvement?) – therefore NOT glaucoma

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Conclusions

▪ Remember, glaucoma should really be a diagnosis of exclusion – need to

consider alternative diagnoses

▪ When considering the potential consequences of glaucoma – there are issues

around patient age and severity of vision loss at baseline