VFA visual field assessment

8/17/2019 VFA visual field assessment

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Seminar on Assessment of Visual field. Seminar on Assessment of Visual field.

Automated Perimetry. Automated Perimetry.

Dr. Ricky Mittal. Dr. Ricky Mittal.


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What is the normal visual

field?

Traquair!island of visionTraquair!island of visionsurrounded "y the sea ofsurrounded "y the sea of

darkness.# darkness.#

$ dimensional strate%ies that$ dimensional strate%ies that

are the foundation of allare the foundation of all &erimetric e'aminations. &erimetric e'aminations.

() a'is* + a'is. () a'is* + a'is.

,inetic &erimetry- ,inetic &erimetry-

e'tent alon% () a'is.e'tent alon% () a'is. Static &erimetry- differential Static &erimetry- differential

li%ht sensitivity *altitude ofli%ht sensitivity *altitude of

the hill of vision alon%the hill of vision alon%

vertical a'is.vertical a'is.


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/'tent of visual field* () a'is- /'tent of visual field* () a'is-


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0asic terminolo%ies 0asic terminolo%ies:: Threshold --

Physiolo%ical ca&acity to detect a stimulus at a %iven Physiolo%ical ca&acity to detect a stimulus at a %ivenlocation* that stimulus intensity that has a 123&ro"a"ility oflocation* that stimulus intensity that has a 123&ro"a"ility of

"ein% seen."ein% seen.

A&ostil"s--

A"solute units of li%ht intensity. A"solute units of li%ht intensity.

4uminance of test tar%et. 4uminance of test tar%et.

5 as"6.$57$ candela8m5 as"6.$57$ candela8m99

Deci"els--

Relative scale* created "y manufacturers. Relative scale* created "y manufacturers.

Attenuation of li%ht "y neutral density filters. Attenuation of li%ht "y neutral density filters.

5d065852 lo% units of attenuation of ma'. stimulus.5d065852 lo% units of attenuation of ma'. stimulus.

Measures sensitivity at each &oint.2to:2d0. Measures sensitivity at each &oint.2to:2d0.


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Sensitivity Vs threshold- Sensitivity Vs threshold-

;nverse relationshi&. ;nverse relationshi&.

;n automated &erimetry* threshold is recorded in the inverted ;n automated &erimetry* threshold is recorded in the inverted

deci"el scale* and dimmer tar%ets have hi%her deci"eldeci"el scale* and dimmer tar%ets have hi%her deci"elvalues.values.

Therefore* threshold inTherefore* threshold in deci"elsdeci"els is directly &ro&rotional tois directly &ro&rotional to

retinal sensitivityretinal sensitivit

y . .


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A&ostil"s Vs deci"els A&ostil"s Vs deci"els--

4umininance of test tar%ets is measured in an a"solute unit* 4umininance of test tar%ets is measured in an a"solute unit*

a&ostil"s.a&ostil"s.

Deci"el is a relative scale created "y manufacturers of Deci"el is a relative scale created "y manufacturers ofautomated &erimeters to measure sensitivity.automated &erimeters to measure sensitivity.

;nverted lo%arithmic scale


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Total deviation -difference "ets threshold measured-difference "ets threshold measured

and value e'&ected in a%e matched normals.and value e'&ected in a%e matched normals.


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lo"al indiceslo"al indices--

Mean deviation- mean difference "et


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&rimarily reflects retinal condition. &rimarily reflects retinal condition. e'cludes conditions affectin% the overall field.e'cludes conditions affectin% the overall field.

PSD- PSD-

small valuenormal field or diffuse loss.small valuenormal field or diffuse loss.

scotoma clearly a"normal.scotoma clearly a"normal.

advanced PSD starts decreasin% if many threshold values nearadvanced PSD starts decreasin% if many threshold values near2d0.2d0.


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SE - ;ntratest test varia"ility* threshold at 52 &redetermined &oints*- ;ntratest test varia"ility* threshold at 52 &redetermined &oints*

ts consistency* &atholo%y.

59.1d0.59.1d0.

BPSD- e'tent of focal loss in the visual field* takin% short term- e'tent of focal loss in the visual field* takin% short term

fluctuations in account i.e.


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laucoma hemifield test-laucoma hemifield test- Bom&ares five ones Galon%Bom&ares five ones Galon%

the nerve fi"re "undlesH inthe nerve fi"re "undlesH inthe u&&er field


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;nference- ;nference- utside normal limits.utside normal limits. I53*2.13.I53*2.13. 0orderline. 0orderline. $3$3 A"normally lo< sensitivity. A"normally lo< sensitivity. 1313 A"normal hi%h sensitivity. A"normal hi%h sensitivity.

hi%her than JJ.13hi%her than JJ.13Within normal limits.Within normal limits.


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0asics of the um&hrey field 0asics of the um&hrey field

analyser-analyser-

Pro@ection ty&e automated static Pro@ection ty&e automated static &erimeter. &erimeter.

Most &o&ular* consistency of "asic Most &o&ular* consistency of "asic

hard


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Stimulus sie- Stimulus sie-oldman stimulusoldman stimulussieG5to1HsieG5to1H

Stimulus duration-2.9 Stimulus duration-2.9second.second.

Ei'ation monitor -- ei@l ,rakau "lind ei@l ,rakau "linds&ot technique* %aes&ot technique* %aemonitorin%.monitorin%.


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Data stora%e. Data stora%e.

STATPAB- com&uterised statistical &acka%e STATPAB- com&uterised statistical &acka%e

Bom&arison of &atients results


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;nter&retation of visual field- ;nter&retation of visual field-

Reco%nise artifacts-

Relia"ility.

Assessment of dama%e . .


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0aseline visual field e'am 0aseline visual field e'am--

9 fields F min. "aseline.9 fields F min. "aseline.

55st st fieldBentral $29 threshold fieldBentral $29 threshold

99nd nd central $29 threshold


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Artifacts Artifacts

4id. 4id.

4ens rimtoo far or the eye is not centered. 4ens rimtoo far or the eye is not centered.

Refractive error. Refractive error. 4earnin% effect. 4earnin% effect.

Pu&illary sie. Pu&illary sie.

Ra&id fati%ue. Ra&id fati%ue.


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Relia"ility- Relia"ility-

EalseEalse &ositivestendency of the &atient to &ress the &ositivestendency of the &atient to &ress thetri%%er not in res&onse to seein% a stimulus "ut attri%%er not in res&onse to seein% a stimulus "ut atrandom* either as a res&onse to an audi"le cue orrandom* either as a res&onse to an audi"le cue or

due to the e'&ectation of the stimulus.due to the e'&ectation of the stimulus. Ratio of such res&onses to the num"er of EP catch Ratio of such res&onses to the num"er of EP catch

trials done.trials done. L$$3EP rate is fla%%ed


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Ei'ation losses-Ei'ation losses-

=ot all fi'ation losses re&resent true loss of fi'ation. =ot all fi'ation losses re&resent true loss of fi'ation.

i%h fi'ation loss may indicate* centre of "lind s&ot


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Short term fluctuations- Short term fluctuations-

Testin% o&tion* sho


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Minimum Briteria for Dia%nosin% Minimum Briteria for Dia%nosin%

Acquired laucoma Acquired laucoma-- A laucoma emifield Test outside normal limits on at least A laucoma emifield Test outside normal limits on at least

t


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/arly defect -- =either e'tensive nor near fi'ation. =either e'tensive nor near fi'ation. Mean deviation inde' GMDH F"etter than Mean deviation inde' GMDH F"etter than Kd0.Kd0. n PD &lot-n PD &lot- 5.I913G57H &oints are "elo< 13 level.5.I913G57H &oints are "elo< 13 level. 9.I 52 &oints "elo< 53 level.9.I 52 &oints "elo< 53 level. Bentral 1Ono &oints havin% less than 51d0 sensitivity.Bentral 1Ono &oints havin% less than 51d0 sensitivity.


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Moderate defect -- MDI59d0. MDI59d0.

5.PDI123G $H &oints5.PDI123G $H &oints II 13 and I 92 &oints13 and I 92 &oints I53.I53.

Bentral 1Ono &oints


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Severe defect --

Any of the follo


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Reco%nition of &ro%ressive dama%e Reco%nition of &ro%ressive dama%e--

5.ne< defect.5.ne< defect.

9.dee&enin% of &re e'isitin% defect.9.dee&enin% of &re e'isitin% defect.

$.e'&ansion of &re e'istin% defect.$.e'&ansion of &re e'istin% defect. :.entire field develo&s decreased sensitivity.:.entire field develo&s decreased sensitivity.


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o<


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Bom&are


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laucoma chan%e &ro"a"ility &ro%ramme-laucoma chan%e &ro"a"ility &ro%ramme-

Point "y &oint &ro"a"ility of any chan%e in "aseline field Point "y &oint &ro"a"ility of any chan%e in "aseline field

and ne< field.and ne< field.

5.ne< defect - $ or more noned%e &oints each of


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eneralied de&ressioneneralied de &ression--

Decline in MD* &I53. Decline in MD* &I53.

fR f


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References References--

;llustrated Automated Static Perimetry .R.Reddy. ;llustrated Automated Static Perimetry .R.Reddy.

Testin% of the Eield of VisionDou%las R.Anderson.Testin% of the Eield of VisionDou%las R.Anderson.

Blinical Decisions in laucoma/lia"eth oda&&*RichardBlinical Decisions in laucoma/lia"eth oda&&*Richard

,.Parrish*Dou%hlas R.Anderson. ,.Parrish*Dou%hlas R.Anderson.

Visual Eield /'aminationA.,.u&ta *ReenaVisual Eield /'aminationA.,.u&ta *Reena M.Bhaudhary*Bharu Tandon. M.Bhaudhary*Bharu Tandon.

Thank youThank you


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..Thank youThank you..

VFA visual field assessment

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