Visual Field Test Hyun Ah Kim

Visual Field Test

Hyun Ah Kim

Department of Neurology, Keimyung University Dongsan Hospital

Visual field test

Keimyung university Dongsan Hospital Department of Neurology

Hyun Ah Kim

Visual pathway Visual field test

At bedside

Confrontation testing of the visual field Amsler grid testing

Convetional methods of Perimetric testing

Static profile perimetry Automated static perimetry

Visual field defect

Visual Pathway Correlation between type of scotoma and location

of disease in the visual pathway

Hill of vision

Blind spot

Temporal visual field Foveolar vision

Nasal visual field

Island of vision in the sea of darkness Top of island : fovea (center of fixation) Blind spot : optic nerve head

Normal Visual field

Blind Spot

Optic disc: 15° nasal from the fovea

axons leaving the retina gather to form optic nerve no photoreceptors, physiologic blind spot compensated by contralateral eye

Visual pathway

Visual field test at bedside

Confrontation testing of the visual field

Amsler grid testing

Visual field test at bedside

Amsler grid testing

Confrontation testing of the visual field

Perimetry

Define the shape and extent of the visual field loss, which in turn provides decisive clues to the kind and location of responsible

Systematic measurement of differential light sensitivity (DLS) in the visual field by the detection of the presence of test targets on a defined background

Threshold sensitivity is highest at fovea and decreases progressively towards the periphery

Retinal sensitivity 1/α threshold

Conventional Methods of Perimetric testing

Hill of vision

Three-dimensional reconstructions of the spatial distribution of visual sensitivity Radial lines extending from the visual field center

Differential luminance sensitivity(DLS)

A measure of the visual ability to detect differences in luminance (between test object and adapting surround)

10*Log(L^max/Ltest object )

Kinetic Perimetry - Goldmann (Arc and bowl) - Tangent screen Static Perimetry

- Humprey

Instruments variables Stimulus size Stimulus duration Background luminance Patients variables

Refractive error

Cataract & media opacity Pupil size

age

Perimetry Important Prerequisites for Perimetry Throughout the examination

Signs of fatigue such as gradual sinking of the upper lid, pupillary miosis, or poor fixation maintenance

Within the central 30° of the field, an appropriate correction is required.

Tangent Screen test Conventional Methods of Perimetric testing Kinetic perimetry

Angular subtence (size)

0, I, II, III, IV, V : 0 is the smallest, V is the largest Luminance intensities

1,2,3,4 : 1 is the dimmest, 4 is the brightest a,b,c,d : a is the dimmest, d is the brightest

Angular velocity 4°/s

Kinetic (Goldmann) Perimetry Kinetic (Goldmann) Perimetry

Advantages of manual kinetic perimetry Better examination of peripheral field

Reveal scotomas that were missed b/w the testing points in static perimetry

Shape of the defects may also be more impressive Severe VL test-retest variability is better

Patients with central scotoma Neuro-ophthalmology

Kinetic (Goldmann) Perimetry

Disadvantages of manual kinetic perimetry Less reliability and reproducibility

Less sensitive in detecting early VFD Lack of fixation monitoring

Lack of normative data

Automated Static Perimetry

<< reliability data>>

Fixation losses : 4/24 - fixation monitoring - gaze tracker

False positive errors : 1/8 -Pt doesn’t respond to stimuli >

9db than previously registered False negative errors : 0/11 -Pt responds to auditory in absence of visual stimuli

The gray scale, containing a conversion of the raw data using the key at the bottom of the readout

- schematic representaion of threshold values it helps to appreciates general pattern of VF The raw data, recording the

luminance, given in decibels(dB), of the dimmest stimulus the subject saw at that position in the visual field

Pattern deviation

= TD + overall sensitity changes

Static profile Perimetry

Advantages of static profile Perimetry Short duration

No examiner bias

Good reliability and reproducibility

Availability of normative data

Disadvantages of static profile Perimetry Within 30° of eccentricity

Profiles of the island(or “hill”) of vision are produced

Particularly good technique for defining the locations and depths of small scotomas Can be used for sequential exams to follow the course of the profile along the changing boundaries of scotomas or even at the foveal projection at the visual field’s center

Static profile Perimetry Automated Static perimetry

Global indices Mean deviation (MD)

Age deviation of pt from the control, negative indicate depressed field and positive indicate higher than normal Pattern standard deviation(PSD)

Represents the degree of irregularity in the field, increase in PSD in a glaucoma pt indicate progression

Corrected pattern standard(CPSD) deviation : eliminates irregularities in VF sec to unreliable pt response.

Automated Static Perimetry

<< reliability data>>

Fixation losses : 0/17 - fixation monitoring - gaze tracker

False positive errors : 1%

-Pt doesn’t respond to stimuli >

9db than previously registered False negative errors : 0%

-Pt responds to auditory in absence of visual stimuli

Automated Static Perimetry

Advantages Disadvantages Best neuro-ophthalmic uses

Computerized threshold Reproducible More objective More standardized Less reliance on a technician Interechnician variability less import ant

Lengthy Tedious

Optic neuropathy Papilledema Chiasmal disorders Repeated follow-up

Goldmann kinetic Short

Driven by technician or doctor Skilled perimetrist or physician can focus attention on suspected defe ct areas

More subjective Depends on the skills of the p erimetrist

Retrochiasmal disorders Neurologically impaired patien ts

Patients who are unable to do a computerized field test Severe visual loss Functional vision loss Tangent screen kinetic Short

Can be performed in the examinati on room

Central 30° only Central field defects Functional visual loss

Compendium of visual field defects

Visual Field Defect

Lesions of LGB : “keyhole defect” quadruple sectoranopia - unusal

Visual field defect

• Fig 4.1

• My vision is getting worse

Absolute and Relative VFDs

Absolute VFD

The I/4e test object or any higher stimulus value is not seen

Relative VFD

One in which the standard test object (I/4e) is seen, but the expected level of light increment sensitivity isnot fully achieved

Topical diagnosis of VFD

Optic nerve

Topical diagnosis of VFD

Chiasm

Wilbrand’s knee - Inferonasal retinal fiber(superotemporal field)

Junctional scotoma - Inferonasal retinal fiber(Ipsilesional optic nerve joining the chiasm)

Retrochiasmal Visual Pathways

Contralateral homonymous hemianopsia Complete homonymous hemianopsias

: any lesion of retrochiasmal pathways,

localization (-)

Homonymous visual field defect in retrochiasmal lesions : optic tract, LGB, optic radiations, visual cortex.

Congruous vs Incongruous VFD

Fibers from each eye are less fully mingled in optic tract and LGB  not perfectly congruous for more anterior retrochiasmal lesions

Become congruous for more posteriorly located lesions

Homonymous visual field defect Topical diagnosis of VFD

Optic tract

RAPD (contralesion) Homonymous hemianopsia (contra, incomgruous)

Bowtie atrophy (contra) Temporal pallor (ipsi)

Optic radiations to Calcarine cortex

From LGB, optic radiations sweep over the temporal horn of lateral ventricle

homonymous contralateral field defect

Inferior fibers(Meyer’s loop)-pass through temporal lobe: lower bank(contralateral upper field) Temporal lobe lesions-”pie in the sky” contralateral homonymous superior quadrantanopia Superior fibers– through parietal lobe: upper bank(contralateral lower field)

Parietal lobe lesions-”pie on the floor” contralateral homonymous inferior quadrantanopia

Macula sparing

Terms usually used in cortical lesions, other lesions cause a relative sparing of central vision.

Fovea has relatively large representation for its size.

Can also occur in visual cortex either MCA or PCA may provide collateral flow to the macula in the occipital pole.

Temporal Crescent

Topical diagnosis of the afferent visual pathway

Lesion site Common causes Findings

Ocular Refractive error, media opacities Vision may improve with pinhole; normal pupillary reactivity

Retina Macular degeneration, CRAO, CRVO Visible retinal abnormality on ophthalmoscopy Optic nerve Inflammatoy lesions(idiopathic optic

neuritis, sarcoid); ischemia (atherosclerotic, vasculitic); infiltrative/

infectious (neoplastic, syphilis)

Afferent pupillary defect present if unilateral; central, centrocecal, or arcuate field defect; disc swelling may be visualized if optic nerve head involved

Chiasm Sellar mass (pituitary adenoma, craniopharyngioma, meningioma, or aneurysm)

Bitemporal hemianopia; optic atrophy

Optic tract Sellar mass Afferent pupillary defect variable; classically incongruous hemianopia; “bow-tie” disc atrophy if long standing Lateral geniculate Stroke Incongruous hemianopia, optic atrophy late; horizontal

sectoanopia or quadruple quadrantanopia suggestive of infarction

Optic radiations(parietal) Stroke, neoplasm Inferior contralateral quadrantanopia; normal pupillary reactivity; defective optokinetic response with targets drawn toward the lesion

Optic

radiations(temporal) Stroke, neoplasm Superior contralateral quadrantanopia; normal pupillary reactivity

Occipital Stroke, neoplasm Congruous contralteral hemianopia with or without macular sparing; normal pupillary reactivity; normal optokinetic response