How to be outstanding in your fields

Andrew Miller MSc MCOptom PG Cert LV

Lead Optometrist Focus Birmingham

Introduction

• What are visual fields

• What do fields mean to the patient

• Measuring Visual Fields

• Why should you care?

• Action Points

• Conclusions

Normal Visual Fields

• The field of vision is defined as the area that is perceived simultaneously by a fixating eye.

• The limits of the normal field of vision are:

– 60° into the superior field,

– 75° into the inferior field,

– 100° temporally,

– and 60° nasally.

• Harry Moss Traquair (1875-1954) "an island of vision or hill of vision surrounded by a sea of blindness".

Hill of Vision

Perceived symptoms of field loss

• “Black in centre of vision”

• “Black round the edges so you just turn your head more”

• Reality

– Simulation specs are poor

– Often loss not well self reported

– Hard to Judge where field loss starts and finishes

FIELD LOSS

Measuring Visual Fields

Static Kinetic

Formal GoldmannHumphreyHenson

InformalAmslerConfrontationObservation

Static Testing

• Size and location of the test target remain constant.

The shape of the island is defined by repeating the threshold measurement at various locations in the field of vision

Retinal sensitivity at a specific location is determined by varying the brightness of the test target.

• Either

– Full Threshold

– Supra Threshold

Static

Kinetic

Formal

Informal

Static Testing

JODY R. PILTZ-SEYMOUR, ONECA HEATH-PHILLIP and STEPHEN M. DRANCE

Static

Kinetic

Formal

Informal

Results from Static Perimetry• Supra Threshold

Results from Static Perimetry• Full Threshold

Kinetic Fields

• Stimulus moved from a non-seeing area of the visual field to a seeing area along a set meridian.

• Repeated along other meridians, usually spaced every 15°.

• In kinetic perimetry, finding locations in the visual field of equal sensitivity.

• Lines joining points of equal sensitivity called isopters.

• Change luminance and the size of the target is changed to plot other isopters.

Static

Kinetic

Formal

Informal

Static

Kinetic

Formal

Informal

Results From Kinetic Perimetry

Informal Fields Testing

• Confrontation Testing

• Amsler Grid

• Observation

Scottish Sensory Centre

Pros and Cons

Pros Cons

Easy Easy to get it wrong

Simple Too Simple

Can be done out in the field.

Not quantifiable

Fields and Low Vision

• Esterman test– 120 targets– Wide test arc (160 degrees horizontally)– Targets are bright– Test is done binocularly– Static Test– Pt. watches fixation light– Pt .press button when light seen

• Gives a real world view of the pattern of greatest loss

Plot example

Loss of Fields : Symptoms and Case Study

• 82 year old man

• Stroke 2 years ago.

• Seen hospital “nothing could be done”

• Stroke has given dad a problem with his left eye.

• Son noticed dad very withdrawn since moving to a new residential home.

• Staff saying he is only interested in the television and ignores people.

Field Plot

Field Plot

Example 2

Why should you care?

• More empathetic working

• Better training outcomes

– Longcane

– Guidedog

• Allows you to think about wider issues

– Positioning in rooms / classrooms

– Placing of items of interest

– Walking with someone else

– Which way to turn

Field Loss

• Field loss causes the problems we suspect.

– Tripping

– Falling over

– Fear

– Isolation

• But not necessarily the symptoms we expect