Clinical Skills: Confrontation Visual Fields

Examination Sequence

Case History

Observe the patient

Visual Acuity

External Examination

External evaluation/observation of the patient

obtain a general impression of the patient's development, health and physical and mental ability

during the External evaluation/observation of the patient, determine og any of the following are present:

physical impairment

postural deviations or body asymmetry

deviations of gait

scarring or evidence of trauma

syndrome characteristics

External testing

- gross physical inspection and evaluation as indicated

- cover test

- pupils

- EOM (versions, pursuits)

- Color vision screening

- Stereopsis

- Near Point Convergence

- Confrontation Visual Fields

Visual field

refers to the sum total of visual perception for an eye fixed on a stationary object of regard with the head and body held in fixed position

Lower animal shave eyes that point

in opposite directions to give a 36o degree field of view

Predatory animals (including humans) have eyes that face

the same direction for stereopsis

Visual fields are always documented from the _____ point of view

patients!

Monocular visual field: Nasal

60 degrees

Monocular visual field: Temporal

100 degrees

Monocular visual field: Superior

60 degree

Monocular visual field: Inferior

75 degree

Monocular visual field: Total Horizontal

160 degrees

Monocular visual field: Total Vertical

135 degreees

Binocular visual field: horizontal

200 degrees

Binocular visual field: Vertical

135

Visual field bincular/ simulatnaous

120 degrees

Hill of vision

a 3D representation of the visual field

Hill of vision center of the graph is the

Point of fixation - fovea

most sensitive!

eye can see a very small, dim point of light

All points of our VF in each eye is set by the

macula/fovea

Hill of vision slope

helps one see how the sensitivyty of the eye changes

wides part of th VF is temporally - but low sensitivity

fastr drop off on the nasal side - there is usualluy overlap from the over eye

Physiological blind spot

corresponds to the optic nerve

5 degrees in size

15 degrees temporal to fixation

How far should a paper be held to find ur blind spot

9-10 inches

Blind spot is _____

tempora

left in left eye

right in right eye

SEE SLIDES FOR DRAWINGS

Prechiasmal

retina

optic nerve

Chiasm

optic chaism

post chiasmal

optic tract

lateral geniculate nucleus

optic radiations

occipital cortext

How do we find a problem in the visual field ?

Visual acuity -- fovea only - central only

Symptoms or signs - reading VA chart

Testing:

screening - confrontation fields

additional - FDT, humphrey, VF test

Campimetry

Visual field assessment using a flat surface

eg. tangent screen

Perimetry

Visual field assessment using a curved background

Goldman or humphrey (static)

Testing Strategy

Static testing

kinetic testing

Static testing

a target of known brightness at suprathreshold level is flashed on briefly within the boundaries of the patient's visual field

Kinetic testing

a stimulus is moved from an area in which it is not seen (infathreshod) into a region where it is visible (suprathreshold)

isopters

boundary between regions of invisibility and visibility

a line that connects all points at which the same size and brightness stimulus can be seen

Infrathreshold

the stimulus intensity is below the level at which can be seen by the patient

suprathreshold

the stimulus is at a level which it can be seen by the patient

Central vision

the central 30 degrees

Peripheral Vision

beyond 30 degrees

The macula correspond to the center

17 degrees diameter of VF

The fovea correspond to the center

5.2 degrees

The foveola correspond to the center

1-1.2 degrees diamter

we name defects by the area

lost!

Complete monocular vision loss

one eye sees one eye does not

Complete binocular vision loss

both eyes are non-seeing

Scotoma

an absolute or relative area of depressed visual function surrounding normal vision

a blind spot!

a permanent or temporary area of depressed or absent vision cased by a lesion of the visual system

absolute scotoma

defects that are blind to any light, no matter how strong

nothing can be seen at all within that area

Relative scotoma

defects that retain some degree of differential light sensitivity

an area where objects of low luminance cannot be seen by larger or brighter ones can be seen - seen as blur

Positive scotoma

the patient realizes that they cannot see in this area

Negative scomtoma

the patient does not realize they are missing anything

Altitudinal field defects

the defect is present above or below the horizontal midline

usually associated with ocular abnormalities

central scotoma

defect in the middle

characteristic of optic nerve disease or macular disease

Hemianopia

blindness in one half of the visual field of one or both eyes

Homonymous

affecting the same part of the visual field of each eye

Right homonymous hemianopia

vision loss right temporal and left nasal field

left homonymous hemianopia

vision loss right nasal field and left temporal field

Binasal heteronymous hemianopia

Loss of nasal visual fields from both eyes

Bitemporal heteronymous hemianopia

Loss of temporal visual fields from both eyes

Quadrantanopia

Loss of vision in a quarter section of the visual field of one or both eyes

homonymous quadrantanopia

same side and same quadrant

Heteronymous Quadrantanopia

binasal or bitemporal

Crossed Quadrantanopia

example: upper quadrant in one eye and lower quandrant in the other eye

Congruous hemianopia

matching

incomplete hemianopia

hemianopia in which the visual fiel defects in both eyes are completely symmetric in extent and intesity

Incongruous defect

incomplete hemianopia

NOT symmetric

NOT matching

Complete

entire half of a visual field

incomplete

not the entire half of the visual field

If the defect is complete

you cannot tell if it is congruous

Vision with Glaucoma

tends to start in the periphery and progress toward the center

field loss is not truly "black"

it is a negative scotoma - do not know they are missing those areas!

Macular degeneration

affects central vision (macular area)

positive scotoma! they know they have the problem

Metamorphopsia

distorted vision

patients may notice this when they look at theur window mini blinds or vertical blinds

Types of Visual Fields

Confrontation VF

Humphrey Frequency Doubling Technology (FDT)

Tangent Screen Test

Goldman Bowl Instrument

Humphrey Field Analyzer

Octopus VF

Other

Confrontation Visual Fields (CVF) Purpose

screen for unknown defects

Quick; reasonable

Confirm known VF loss

Educate patient

Nerve fibers of the retina enter in

a very specific pattern

a defect or problem in these tissues causes a recognizable visual field defect/ scotoma

SEE SLiDE 51

Temporal Visual field is projected

onto the nasal retina

Nasal Visual Field is projected

onto the temporal retina

Lesions anterior to the optic nerve will be

unilateral

Nasal fibers

cross at the level of the chiasm

Defects after the chiasm will

respect the vertical

SEE SLIDE 52

Complete dissection on the left ON will result in

scotoma/blind spot left eye with a normal right visual field

lesion at the optic chiasm

bi temporal hemianopia

Complete interruption of the optic radiations

contralateral total homonymous hemianopia

Posterior occipital lobe lesions

homonymous hemianopic defects but may spare the macula

Important Questions to ask

Is the defect in the field of vision - in one eye or both?

one eye - in front of chiasm

Does it respect the horizontal?

if it does - in front of the chiasm

Does it respect the vertical

if it does -at or behind the chiasm

Is the field loss homonymous

if yes - behind the chiasm

if the defect is bilateral, how congruous is it?

how far back it is

CVF set up

Doc 60cm

Targets 30 cm

CVF lighting

doctor and hands is the target

overhead light on full

stand light on over patient head pointed at Dr - Stimulus

CVF position of the patient and examiner

eye level

CFV correction or no correction

no correction

Subjective test and Static test

SEE SLIDES AND MANUAL