This document discusses automated perimetry and visual field testing. It covers basic concepts like Traquair's definition of the visual field and automated perimetry measuring differential light thresholds. It describes parameters for visual field testing like stimulus size and color. Common threshold tests like 30-2, 24-2, and 10-2 are outlined along with interpretation of results and statistical indices. Criteria for detecting glaucoma defects and advantages of short-wavelength automated perimetry (SWAP) are summarized.

1. AUTOMATED PERIMETRY
DR INDEEVAR V MISHRA
MM JOSHI EYE HOSPITAL,
HUBLI.

2. BASIC CONCEPTS
• TRAQUAIR'S HAS DEFINED THE VISUAL FIELD AS BEEN A HILL
ISLAND OF VISION IN A SEA OF DARKNESS TESTING ALONG X-Y
AXES OF THIS 3 DIMENSIONAL AREA DETERMINES THE LOCATION
IN THE VISUAL FIELD AND ALONG THE Z AXIS IDENTIFIES THE
VISIBILITY THRESHOLD.
• AUTOMATED PERIMETRY - " DIFFERENTIAL LIGHT THRESHOLD –
ABILITY TO DIFFERENTIATE AN ILLUMINATED TARGET AGAINST
AN ILLUMINATED BACKGROUND."

3. BASIC CONCEPTS
--- CONTD
THRESHOLD
• LUMINANCE OF STIMULI THAT IS SEEN 50% OF TIMES IT IS
PRESENTED
• LOGARITHMIC UNIT DB ( DB PROP. 1 / BRIGHTNESS )
• BRACKETING STRATEGY ( 4 - 2 - 2 ALGORITHM )
• SUPRA THRESHOLD - 95 % CHANCE A STIMULUS IS SEEN.
• INFRA THRESHOLD - 5% CHANCE A STIMULUS IS SEEN.

4. BASIC MACHINE DESIGN
• ILLUMINATED HEMISPHERICAL BOWL 33 CM
AWAY WITH TARGET OF FIXATION
• STIMULI - SPOT OF LIGHT - LED / PROJECTION
SYSTEM / COMP. VIDEO MONITOR
• HFA - II ( 700 SERIES ) ASPHERICAL BOWL 30 CMS
AWAY ,SMALLER ,MORE ERGONOMIC STIMULI IN
PERIPHERY MORE CLOSER,

5. FIXATION CONTROL
• CC TV MONITOR
• HEIJL - KRAKAU BLIND SPOT METHOD
• GAZE TRACKER
• FULL TIME TWO VARIABLE GAZE MONITOR
• IMAGE ANALYSIS
• ERRORS - UPWARD / DOWNWARD
• FIXATION CHECKED 100 % OF STIM. TIME
• NO TESTING TIME FOR FIXATION CHECK

6. PARAMETERS RECOMMENDED
FOR TESTING
• FOVEAL FIXATION TARGET – SMALL AND LARGE
DIAMOND WITH YELLOW LIGHTS.
• GOLDMANN SIZE III TARGET FOR STIMULI & BLIND
SPOT CHECK. IF EXCESSIVE FIXATION LOSS IT CAN BE
DECREASED TO II OR I OR IF VISION LESS THAN 6/36
THAN IT CAN BE INCREASED TO V.
• WHITE STIMULUS COLOUR
• NORMAL TESTING SPEED. CAN BE SLOW DOWN IF
PATIENT IS SLOW TO RESPONSE.
• FOVEAL THRESHOLD - ON / OFF

7. THRESHOLD TESTS
• CENTRAL 30-2 – 76 POINTS ARE TESTED . EACH
POINT 6 DEG APART. STRADDLING THE
HORIZONTAL AND VERTICAL AXIS SO THAT THE 2
INNER MOST TEST POINTS ARE 3 DEG FROM
FIXATION POINT.
• CENTRAL 24-2 – 56 POINTS ARE TESTED . AVOIDS
RIM ARTIFACTS.
• CENTRAL 10-2 – 68 POINTS SPACE 2 DEG APART.
USEFUL IN ADVANCE DISEASE WITH SPILT
FIXATION.
• MACULAR THRESHOLD TEST – SQUARE GRID OF 16
POINTS EACH 2 DEG APART , WITH EACH POINT
THRESHOLDED 3 TIMES.

8. 30 – 2 24 – 2 Macular threshold

9. INTERPRETATION
FACTORS FOR CONSISTENCY IN TESTING
• BEST REFRACTIVE CORRECTION USED. CONTACT
LENS TO AVOID RIM ARTIFACTS.
• PUPIL DIAMETER – AT LEAST 3.5 MM IN SIZE.
• VISUAL ACUITY
• DATE & TIME OF TESTING
• AGE-FOR COMPARISON WITH NORMATIVE DATA
• SHORT TERM FLUCTUATION-FLUCTUATION
OCCURRING WITHIN THE TEST. SHOULD BE <3DB.

10. INTERPRETATION ----CONTD.
FIXATION LOSSES: 10/12 XX
FALSE POS ERRORS : 0/7
FALSE NEG ERRORS :0/6
TEST DURATION : 16:20

11. STATISTICAL GLOBAL INDICES
• MD – MEAN DEVIATION – SENSITIVE TO TOTAL LOSS
• PSD – PATTERN STANDARD DEVIATION – SENSITIVE TO LOCALIZED
LOSS.
• CPSD – CORRECTED PATTERN STANDARD DEVIATION – PSD
CORRECTED FOR SHORT TERM FLUCTUATION. VERY SENSITIVE
INDEX.

12. GLAUCOMA DEFECT WITH AUTOMATED
PERIMETRY- ANDERSON'S
CRITERIA
• 3 OR MORE CONT.NON EDGE
POINTS WITH >= 5 DB LOSS
• 2 OR MORE CONT. NON EDGE
POINTS WITH >=10 DB LOSS
• DIFF. OF 10 DB ACROSS
NASAL HOR. MERIDIAN AT 2
OR MORE ADJ. POINTS
( NASAL STEP.)
• GHT - ONL
• PSD PLOT - >= 3 PTS , P< 5%
OF WHICH ONE < 1%
• CPSD ( P <5% ) GHT ONL

13. SWAP
• TESTS SUBSET OF GANGLIONS AFFECTED EARLIER &
SELECTIVELY -- BLUE / YELLOW
• REDUCES THE REDUNDANCY OF RESPONSIVENESS TO
STIMULI
• INTENSE YELLOW BACKGROUND - BLEACHES GREEN /
RED CONES
• BLUE STIM. ( 440NM ) - ISOLATES BLUE CONES
• ADAPTATION - 3 MTS. ROOM ILLUMINATION - MINIMAL
• STIMULUS SIZE & BS CHECK SIZE V
• MEAN THRESHOLD VALUES LOWER THAN SAP - GRAY
SCALE DARKER
• STAT PAC PROBABILITY PLOTS MORE RELIABLE

14. SWAP -- CONTD
• FIELD DEFECT PRECEDES SAP BY >= 3 YRS
• ONCE ABNORMAL - REMAIN ABNORMAL ( NO RECOVERY
OF DAMAGED BLUE CONES )
• NO ROLE IN ADVANCED POAG / ADVANCED LENTICULAR
CHANGES / COLOUR VISION ABNORMALITIES
• MOST USEFUL IN YOUNGER GLAUCOMA SUSPECTS,
OHT , POAG WITH MILD TO MOD.DAMAGE
• TIME CONSUMING - SITA OPTIMISED FOR SWAP / FAST
PAC CAN BE USED