Glaucoma or not glaucoma that is the question

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

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

“Typical” glaucoma

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

Other clinical features

IOP 25 mmHg

CCT 510 microns

What is the definition of glaucoma?

Casson et al 2012 CEO

What is the definition of glaucoma?

Casson et al 2012 CEO

Glaucomatous visual field defects

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

Highlight issues with visual fields

- Pattern

- Depth

- Structure-function

Glaucomatous vs non-glaucomatous visual field loss

▪

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

words)

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

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

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

Poll: Structure-function correlation – is this

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

Features not typical of glaucoma?

Optic nerve scan typical

pattern (arcuate)

Features not typical of glaucoma?

Optic nerve scan typical

pattern (arcuate)

However, macula

scan NOT typical

Incomplete arcuate…

loss is too focal

Features not typical of glaucoma?

Note the attenuation of

retinal arteries and the

presence of an arterial ghost

Features not typical of glaucoma?

OCT-A visualises loss of

retinal perfusion and

attenuation of vessel

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

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)

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

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

Clinical findings

•

IOP 10-13 mmHg

•

Pachymetry 550 microns

•

No systemic disease

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

Clinical findings

•

IOP 10-13 mmHg

•

Pachymetry 550 microns

•

No systemic disease

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

Clinical findings

•

IOP 10-13 mmHg

•

Pachymetry 550 microns

•

No systemic disease

Poll: is this glaucoma – yes/no?

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)

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)

Extra testing – OCT angiography

Again… deep

vascular loss – not

typical of glaucoma

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

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?

Follow up appointments

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

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

6/6

Pressures

15

13

Pachymetry

576

569

Clinical data

Longitudinal data

No significant structural change (just due to

floaters)

No change in visual field defect (some

improvement?) – therefore NOT glaucoma

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