2.07 Visual Fields

Why do we do perimetry

To assess the health of the visual pathway

Check for glaucoma, tumors, strokes, brain injury

What are the 2 types of perimetry

Kinetic and static

What are the 3 types of kinetic perimetry

Gross (arc) perimetry

Goldmann manual

Octopus semi automated

Classification of stimulus size and intensity

Kinetic perimetry general principles

Involves a moving target

Gross perimetry procedure

A target is moved from an area of non seen to seen - patient reports when the targett first becomes visible and if the target diappears again

Goldmann manual perimetry

Patients eye is centered in the middle and praticitoner moves stimulus from the other side and marks where pt says they can see - maps the extent of the VF (isopter)

Can also be semi automated

Octopus semi automated perimeter

Patient focuses on a central target and presses a button when they see the light move from non seeing to seeing areas of the visual field - maps the isopter

Light varies in size, brightness and location

What is this VF plot called

Isopter

Used in kinetic perimetry - goldmann and octopus

Kinetic perimetry advantages and disadvantages

Types of static perimetry

Amsler grid

Suprathreshold

Threshold

Amsler grid

Grid of lines

Pt looks at centre of grid from 30cms away

near correction worn (not bifocals or varifocals)

Pt reports if they see any distortion, fading of lines

What disease can this amsler chart detect

Wet AMD

VF loss

What disease can this amsler chart detect

Defects associated with toxicity (drugs)

What disease can this amsler chart detect

Detection of scotomas

What disease can this amsler chart detect

Detection of metamorphopsia (distortion)

What disease can this amsler chart detect

Detection of more subtle distortion

What disease can this amsler chart detect

More sensitive to subtle disturbances

Static perimetry general principles

Types of static perimeters

Humphrey field analyser (HFA 2)

Humphrey field analyser 3

Henson 7000

Henson 9000

Easyfield

Dicon TKS5000

Frequency doubling technology (FDT)

Octopus 900

What is a threshold

The intensity of a stimulus that is JUST visible

Stimuli brightee than the threshold are seen

Stimlus dimmer than the threshold is not seen

The threshold varies with position within the visual field (centre most sensitive)

How to calculate sensitivity from threshold

1/threshold = sensitivity

Static perimetry used a logarithmic scale because…

Static perimetry - decibel scale

1 dB step change is perceived the same along the whole range

dB scle is a relative scale - based on maximum luminance the instrument can generate

What size stimulus does static perimetry use and how long is it displayed for

Goldmann size 3

200ms

Size is fixed, brightness varies

Static perimetry procedure

Which diseases give tunnel vision/macular sparing

Glaucoma

Retinal detachment

Retinitis pigmentosa

Tumours

Diabetic retinopathy

Central visual field testing

Test a maximum eccentricity of 25-30 degrees from fixation

Useful for testing VF of people with tunnel vision

Full threshold staircase method

Which algorithms are threshold

SITA, ZEST, ZATA

HFA visual field plot

Threshold tests advantages and disadvantages

Difference between threshold and suprathreshold screening

Threshold VF determines the dimmest light stimulus a person can detect at various points in their VF - measuring sensitivity

Suprathreshold VF uses stimuli that are brighter than the expected threshold to identify significant vision loss but doesnt measure exact sensitivity

Suprathreshold screening

Stimuli brighter than expected threshold so patient is expected to see all the stimuli presented

If pt misses a stimulus it can be presented again and if they still miss it a brighter stimulus can be presented in the same location

How does suprathreshold determine how bright the test stimulus is

Age matched

Dan be wide variation within a group (eg refractive eroro)

More variability in older pts

Threshold test at a small number of central locations

Suprathreshold test advantages and disadvantages

Multiple stimulus tests principles

Multiple stimulus tests Advantages and disadvantages

Testing closer to fixation test pattern

Good for advanced glaucoma

Testing further into the perimetry test pattern

Esterman binocular test pattern

Need to have 120º binocular VF to legally drive

Short wavelength automated perimetry (SWAP)

•A blue, Goldmann V stimulus displayed on a bright (100 cd/m2) yellow background.

•Preferentially stimulates the short-wavelength (koniocellular) pathway.

SWAP disadvantages

Frequency doubling technology (FDT)

Sine grating like stimulus thought to stimulate the magnocellular pathway but now known this isnt the case

FDT avantages and disadvantages

What to think about when deciding which test to choose

Which test do you choose - What are you testing for?

Which test do oyu choose - what am i testing for flowchart

How to record the results of the VF test

State the instrument used, program/algorithm, moderate/fast/faster, test pattern

If no defects - all seen R&L

If defects - be specific where they missed points

What are the HFA reliability indicies

Reliability indicies - fixation losses

Reliability Indices - false positives

Reliability indicies- false negatives

Reliability indicies- gaze tracking

What does this visual field plot show us

‘Raw’ sensitivity of the eye

The higher the value = the more sensitive the eye is - can detect dimmer lights

What is this VF plot called

Greyscale

What are the global indicies

mathematical summaries of all sensitivity values

VFI (visual field index)

MD (mean deviation)

PSD (pattern standard deviation)

Global indicies - VFI

global indicies - MD

global indicies - PSD

What is a total deviation map

What people are included in the normative database

What is a pattern deviation map

Highlights localised VF loss (compares pt with themselves)

What is glaucoma hemifield test

Glaucoma hemifield test categories

If VF defect respects the horizontal midline its caused by..

A retinal defect

If VF defect respects the vertical midline its caused by..

Defect after the optic chiasm

What kind of defect is this

Arcuate

What kind of defect is this

Paracentral

What kind of defect is this

Nasal step

Assymetric involvement of superior and imferior field

What kind of defect is this

Temporal wedge defect

What kind of defect is this

Altitudinal

What kind of defect is this

Advanced glaucoma

Notes to remember

which VF machine is the reference standard according to NICE

The Humphrey field analayzer (HFA)

Identifying change - why shouldnt you compare between different instruments

What is this VF plot showing

Bitemporal hemonopia -reduced VF temporally in both eyes

Optic chasm defect

What is this VF plot showing

Homonymous hemionopia - defect after optic chiasm

What is this VF plot showing

Homonymous superior quadrontopia

What is this VF plot showing

Homonymous inferior quadrontopia

What is this VF plot showing

Homonymous hemianopia with macular sparing

What is this VF plot showing

Anterior ischaemic optic neuropathy

What is this VF plot showing

Retinitis pigmentosa

What is this VF plot showing

Binasal defect

What is this VF plot showing

VF artefacts

Lid ptosis - lid covers pupil

(Trial) Lens atefact - fault in machine set up

Attentional artefact - press too much or lose attention and domt press

Advantages and disadvantages of pre screening the patient

Advantages and disadvantages of post screening the patient

Henson multiple stimulus

• how it works

• Threshold or suprathreshold

• VF measured

• Use for

Multiple lights shown quickly in different locations.

Suprathreshold.

Central 30°.

Screening for glaucoma. Fast, good for busy clinics.

Humphrey C-76

• how it works

• Threshold or suprathreshold

• VF measured

• Use for

Static test using a fixed suprathreshold intensity.

Suprathreshold.

Central 76 points (wide area).

Screening for large defects.

Octopus 30-2

• how it works

• Threshold or suprathreshold

• VF measured

• Use for

Static perimetry with threshold strategy.

Threshold.

Central 30°.

Monitoring and routine exams in glaucoma or neuro cases.

Henson ZATA 24-2

• how it works

• Threshold or suprathreshold

• VF measured

• Use for

Static perimetry with adaptive thresholding (ZATA algorithm)

Threshold.

Central 24°.

Monitoring glaucoma. Faster than standard threshold tests.

Humphrey FF 120

• how it works

• Threshold or suprathreshold

• VF measured

• Use for

Tests 120 locations with fixed intensity.

Suprathreshold.

Wide field, central and peripheral.

Screening for field loss, especially neurological.

FDT C-20

• how it works

• Threshold or suprathreshold

• VF measured

• Use for

Frequency Doubling Technology, tests magnocellular cells -(damaged in glaucoma)

Suprathreshold (screening) or threshold versions exist.

Central 20°.

Early glaucoma detection, quick screening.

Humphrey SITA faster 24-2C

• how it works

• Threshold or suprathreshold

• VF measured

• Use for

Static perimetry with improved speed and accuracy.

Threshold.

Central 24° + extra central points.

Routine monitoring of glaucoma, faster than SITA Standard.

Humphrey SITA standard 10-2

• how it works

• Threshold or suprathreshold

• VF measured

• Use for

Fine grid of test points near fixation.

Threshold.

Central 10°.

Monitoring macular damage, advanced glaucoma, retinal disease.

Octopus kinetic perimetry

• how it works

• Threshold or suprathreshold

• VF measured

• Use for

Moving targets (kinetic), manually plotted.

Threshold/Suprathreshold: Variable (can be both).

Full field, including far periphery.

Neurological cases, driving assessments, peripheral loss.

Which test would be best for a routine person with no symtoms but have a family history of glaucoma and why

Humphrey SITA faster 24-2C

Threshold test – detects subtle early changes.

Faster than SITA Standard – saves time with similar accuracy.

24-2 grid – covers central 24°, ideal for glaucoma.

Extra central points (“C”) – improves detection near fixation.

Low patient fatigue – short test helps maintain attention.

Good for early glaucoma – suitable for high-risk, asymptomatic patients.