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• Son noticed dad very withdrawn since moving to a new residential home.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