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HUMPHREY ZEISS VISUAL FIELD USER MANUAL

Posted on 22-05-2021  by admin

(Redirected from Humphrey Visual Field Analyser)
 1. Zeiss Humphrey Visual Field
 2. Zeiss Visual Field Machine Manual
 3. Humphrey Visual Field User Manual
 4. Zeiss Humphrey Visual Field Analyzer

Figure 1 - Humphrey Field Analyser

Humphrey field analyser (HFA), is a tool for measuring the human visual field,
it is used by optometrists, orthoptists and ophthalmologists, particularly for
detecting monocular visual field.[1]

The results of the Analyser identify the type of vision defect. Therefore, it
provides information regarding the location of any disease processes or
lesion(s) throughout the visual pathway. This guides and contributes to the
diagnosis of the condition affecting the patient's vision. These results are
stored and used for monitoring the progression of vision loss and the patient's
condition.[2]

Humphrey field analyser (HFA), is a tool for measuring the human visual field,
it is used by optometrists, orthoptists and ophthalmologists, particularly for
detecting monocular visual field. The results of the Analyser identify the type
of vision defect. Therefore, it provides information regarding the location of
any disease processes or lesion(s) throughout the visual pathway. Completely
Refurbished Matrix 715 Zeiss Humphrey Matrix Visual Field. Accessories include
keyboard/mouse, patient response button, dust cover, and user manual.

 * 2Method of assessment
 * 3Interpreting results
   * 3.2Plots
 * 4Advantages and Disadvantages


MEDICAL USES[EDIT]

The Analyser can be used for screening, monitoring and assisting in the
diagnosis of certain conditions. There are numerous testing protocols to select,
based on the purpose. The first number denotes the extent of the field measured
on the temporal side, from the centre of fixation, in degrees. The '-2'
represents the pattern of the points tested.[3] They include:

 * 10-2: Measures 10 degrees temporally and nasally and tests 68 points. Used
   for macula, retinal and neuro-ophthalmic conditions and advanced glaucoma[4]
 * 24-2: Measures 24 degrees temporally and 30 degrees nasally and tests 54
   points. Used for neuro-ophthalmic conditions and general screening[5] as well
   as early detection of glaucoma[6][7]
 * 30-2: Measures 30 degrees temporally and nasally and tests 76 points. Used
   for general screening, early glaucoma and neurological conditions[6]

The above tests can be performed in either SITA-Standard or SITA-Fast. SITA-Fast
is a quicker method of testing. It produces similar results compared to
SITA-Standard, however repeatability is questionable and it is slightly less
sensitive[8][9]

There are additional tests for more specific purposes such as the following:

 * Esterman – Used to test the functionality of a patient's vision to ensure
   they are safe to drive, as requested by VicRoads, Australia[10][11]
 * SITA SWAP: Short Wavelength Automated Perimetry (SWAP) is used for detection
   of early glaucomatous loss[5]


METHOD OF ASSESSMENT[EDIT]

Figure 2 - Chin Rest and Lens Holder

The Analyser test takes approximately 5–8 minutes, excluding patient set up.
There are multiple steps which need to be done before commencement of the test
to ensure reliable results are attained.

The test type and eye are firstly selected and the patient's details are
entered, including their refractive error. The Analyser will provide a lens
strength and type (either spherical and/or cylindrical), if required for the
test. In these instances, wire-rimmed trial lenses are generally used, with the
cylindrical lens placed closest to the patient so the axis is easily read. The
clinician can alter the fixation targets as per necessary (see Fixation Targets
for advice).[12]

Before putting the patient onto the machine, the requirements of the test itself
are clearly explained. The patient is instructed to maintain fixation on the
central target and is given a buzzer to only press when they see a light
stimulus. It is not possible to see every light and some lights appear
brighter/duller and slower/faster than others. The eye not being tested is
patched and the room lights are dimmed prior to commencement of the test.[12]

The patient is positioned appropriately and comfortably against the forehead
rest and chin rest. Minor adjustments to the head position are made to centre
the pupil on the display screen to allow eye monitoring throughout the test. The
lens holder should be as close to the patient's eye as possible to avoid
artefacts (see Disadvantages for possible artefacts).


ZEISS HUMPHREY VISUAL FIELD

It is important for the patient to blink normally, relax and maintain
concentration throughout the test. This will increase the reliability of
results.[12]

Figure 3 - Fixation targets left: central, middle: small diamond, right: large
diamond


HOW IT WORKS[EDIT]

The Analyser projects a series of white light stimuli of varying intensities
(brightness), throughout a uniformly illuminated bowl. The patient uses a
handheld button that they press to indicate when they see a light. This assesses
the retina's ability to detect a stimulus at specific points within the visual
field. This is called retinal sensitivity and is recorded in 'decibels' (dB).[1]

The Analyser currently utilises the Swedish Interactive Thresholding Algorithm
(SITA); a formula which allows the fastest and most accurate visual field
assessment to date. Results are then compared against an age-matched database
which highlights unusual and suspicious vision loss, potentially caused by
pathology.[8]


FIXATION TARGETS[EDIT]

There are different targets a patient can fixate on during the test. They are
chosen on the basis of the patient's conditions.[12]

 * Central target: Yellow light in the bowl's centre
 * Small diamond: For patients who cannot see the central target such as those
   with macular degeneration. The patient looks into the centre of the four
   lights
 * Large diamond: For patients who cannot see the above two[12]





INTERPRETING RESULTS[EDIT]


RELIABILITY INDICES[EDIT]

Issues of reliability are critical in result interpretation. These include, but
not limited to, the patient losing concentration, closing their eyes or pressing
the buzzer too frequently. Monitoring fixation is made visible via the display
screen and gaze tracker, located at the bottom of the printout. The degree of
reliability is determined by the reliability indices located on the printout
(Fig. 4). These are assessed first and allow the examiner to determine if the
end results are reliable. These indices include:

 * Fixation Losses: Recorded when a patient responds to a stimulus that is
   projected on to area of their blind spot. Fixation losses exceeding 20%, are
   denoted with an 'XX' next to the score, and deems results unreliable[12]
 * False Positives: Recorded when a patient responds when there is no stimulus
   present. This patient is often referred to as 'buzzer happy'. False positives
   exceeding 15% are denoted with an 'XX' and results are considered unreliable.
   This may indicate that the patient is anxious and concerned about missing
   targets[12]
 * False Negatives:Recorded when a patient does not respond to brighter stimuli
   where a duller stimulus has already been seen. High false negative scores
   indicate that the patient is fatigued, inattentive, a malingerer or has
   genuine significant visual field loss.[12] Literature presents various
   percentages regarding reliability. However, majority of the literature
   defines that false negatives exceeding approximately 30% deem results
   unreliable.[13][14][15]


PLOTS[EDIT]

Figure 4 - Analyser Printout
1: Reliability Indices
2: Numerical Display
3: Grey Scale
4: Total Deviation
5: Probability Display
6: Pattern Deviation
7: Global Indices
8: Glaucoma Hemifield Test
9: Visual Field Index

After reliability is determined, the remaining data is assessed.

NUMERICAL DISPLAY[EDIT]

The numerical display represents raw values of patient's retinal sensitivity at
specific retinal points in dB. Higher numbers equate to higher retinal
sensitivities. Sensitivity is greatest in the central field and decreases
towards the periphery. Normal values are approximately 30 dB while recorded
values of <0 dB equate to no sensitivity measured.[16]

GREY SCALE[EDIT]

The grey scale is a graphical representation of the numerical display, allowing
for easy interpretation of the field loss. Lower sensitivities are indicated by
darker areas and higher sensitivities are represented with a lighter tone.[3]
This scale is used to demonstrate vision changes to the patient but is not used
for diagnostic purposes.

PATTERN DEVIATION[EDIT]

The numerical total demonstrates the difference between measured values and
population age-norm values at specific retinal points.[3]

 * Negative values indicate lower than normal sensitivity
 * Positive indicates higher
 * 0 equals no change[3]

The statistical display (located below the numerical total) demonstrates the
percentage of the normal population who measure below the patient's value at a
specific retinal point. The probability display provides this percentage a key
for interpreting the statistical display.[3] For example, the darkest square in
the key represents that <0.5% of the population would also attain this result,
indicating that the vision loss is extensive. The Total Deviation plots
highlight diffuse vision loss (i.e. the total departure from the age-norm).[17]

TOTAL DEVIATION[EDIT]

The pattern deviation provides a numerical total and statistical display as the
Total Deviation plot. However, it accounts for general reductions of vision
caused by media opacities (e.g. cataract), uncorrected refractive error,
reductions in sensitivity due to age and pupil miosis. This highlights focal
loss only (i.e. vision loss suspected from only pathological processes).[16]
Therefore, this is the main plot referred to when making a diagnosis. The
Pattern Deviation plot is generally lighter than the Total Deviation because of
the factors accounted for.

GLOBAL INDICES[EDIT]

Figure 5 - Types of Visual Field Defects (right eye)
A: Central scotoma
B: Centrocaecal scotoma
C: Nasal Step
D: Superior Arcuate
E: Nasal Wedge defect
F: Superior Nasal quadrantanopia
G: Superior Altitudinal
H: Nasal hemianopia
I: Enlarged Blind Spot with Paracentral scotoma located 15 degrees superiorly

These provide a statistical summary of the field with one number. Although not
used for initial diagnosis, they are essential for monitoring glaucoma
progression.[3] They include:

 * Mean Deviation (MD): Derived from the Total Deviation and represents the
   overall mean departure from the age-corrected norm.[18] A negative value
   indicates field loss, while a positive value indicates that the field is
   above average. A P value is provided if the global indices are abnormal. It
   provides a statistical representation of the population. For example, P <2%
   means that less than 2% of the population have vision loss worse than
   measured[19]
 * Pattern Standard Deviation (PSD): Derived from the Pattern Deviation and thus
   highlights focal loss only. A high PSD, indicating irregular vision, is
   therefore a more useful indicator of glaucomatous progression, than the MD[3]

GLAUCOMA HEMIFIELD TEST (GHT)[EDIT]

The Glaucoma Hemifield Test (GHT) provides assessment of the visual field where
glaucomatous damage is often seen. It compares five corresponding and mirrored
areas in the superior and inferior visual fields.[3][20] The result of either
'Outside Normal Limits' (significant difference in superior and inferior
fields), 'Borderline' (suspicious differences) or 'Within Normal Limits' (no
differences) is only considered when the patient has, or is a suspect for,
glaucoma.[20] This is only available in 30-2 and 24-2 Analyser protocol.[3]

VISUAL FIELD INDEX (VFI)[EDIT]


ZEISS VISUAL FIELD MACHINE MANUAL

The VFI reflects retinal ganglion cell loss and function, as a percentage, with
central points weighted more.[21]


HUMPHREY VISUAL FIELD USER MANUAL

It is expressed as a percentage of visual function; with 100% being a perfect
age-adjusted visual field and 0% represents a perimetrically blind field. The
pattern deviation probability plot (or total deviation probability plot when MD
is worse than -20 dB) is used to identify abnormal points and age corrected
sensitivity at each point is calculated using total deviation numerical map. VFI
is a reliable index on which glaucomatous visual field severity staging can be
based.[22]

The shaded pattern of vision loss provided on the Pattern Deviation plot allows
for diagnosis of the type of vision loss present. This contributes to other
clinical findings in the diagnosis of certain conditions. The types of vision
loss and associated conditions are not described in the extent of this article,
however Figure 5 provides typical examples of visual field loss seen. Refer to
#See also for more information.


ADVANTAGES AND DISADVANTAGES[EDIT]


ADVANTAGES[EDIT]

 * Provides a comprehensive visual field assessment and ensures reliable
   results[12]
 * Compares patient's data to age-matched populations[12]
 * Distinguishes focal from diffuse vision loss[12]
 * Figure 6 - Artefacts (right eye)
   A: Aphakia
   B: Rim artefact
   C: Chin slip
   D: Lens position
   E: Corneal opacity
   F: Keratoconus
   G: Ptosis
   H: Pupil Miosis - 1mm
   I: Pupil Miosis - 3mm
   Can be used for patients who are wheelchair users, hearing impaired, have
   postural and fixation problems and/or very low visual acuity[12]
 * Provides a baseline measurement
 * Simple for the examiner to perform and interpret


DISADVANTAGES[EDIT]

 * Requires a higher level of patient understanding and concentration compared
   to other visual field tests[9]
 * Time-consuming
 * Learning effect: new patients improve as more tests are performed due to
   understanding of the test conditions. Consider the third test as the baseline
   result[23]
 * Potential for artefacts (i.e. uncharacteristic vision loss) (fig. 6). Below
   is a list of possible artefacts and a representation of how they may appear.
   These can however, be managed with correct patient setup.
   * Uncorrected refractive error and aphakia cause significant decrease in
     visual field sensitivity[3]
   * Rim of trial frame can simulate glaucomatous loss[24]
   * Media opacities and keratoconus cause decreased sensitivity[3]
   * Ptosis cause superior visual field loss[3]
   * Miosis cause decreased peripheral sensitivity[3]


SEE ALSO[EDIT]


REFERENCES[EDIT]


ZEISS HUMPHREY VISUAL FIELD ANALYZER

 1.  ^ abLanders, John; Sharma, Alok; Goldberg, Ivan; Graham, Stuart L (February
     2010). 'A comparison of visual field sensitivities between the Medmont
     automated perimeter and the Humphrey field analyzer'. Clinical &
     Experimental Ophthalmology. doi:10.1111/j.1442-9071.2010.02246.x.
     PMID20447123.
 2.  ^Kedar, Sachin; Ghate, Deepta; Corbett, JamesJ (2011). 'Visual fields in
     neuro-ophthalmology'. Indian Journal of Ophthalmology. 59 (2): 103–109.
     doi:10.4103/0301-4738.77013. PMC3116538. PMID21350279.
 3.  ^ abcdefghijklmKanski, J. J.; Bowling, B. (2011). Clinical Ophthalmology.
     Edinburgh: Elsevier Saunders.
 4.  ^Asaoka, Ryo; Vavvas, Demetrios (20 June 2014). 'Mapping Glaucoma Patients'
     30-2 and 10-2 Visual Fields Reveals Clusters of Test Points Damaged in the
     10-2 Grid That Are Not Sampled in the Sparse 30-2 Grid'. PLoS ONE. 9 (6):
     e98525. doi:10.1371/journal.pone.0098525. PMC4064971. PMID24950300.
 5.  ^ abKhoury, Johnny, M.; Donahue, Sean, P.; Lavin, Patric, J.; Tsai, James
     (1999). 'Comparison of 24-2 and 30-2 Perimetry in Glaucomatous and
     Nonglaucomatous Optic Neuropathies'. Journal of Neuro-Ophthalmology. 19
     (2): 100–108. doi:10.1097/00041327-199906000-00004.
 6.  ^ abNouri-Mahdavi, Kouros (December 2014). 'Selecting visual field tests
     and assessing visual field deterioration in glaucoma'. Canadian Journal of
     Ophthalmology. 49 (6): 497–505. doi:10.1016/j.jcjo.2014.10.002.
 7.  ^Huang, Charles Q.; Carolan, James; Redline, Daniel; Taravati, Parisa;
     Woodward, Kimberly R.; Johnson, Chris A.; Wall, Michael; Keltner, John L.
     (1 March 2008). 'Humphrey Matrix Perimetry in Optic Nerve and Chiasmal
     Disorders: Comparison with Humphrey SITA Standard 24-2'. Investigative
     Ophthalmology & Visual Science. 49 (3): 917–23. doi:10.1167/iovs.07-0241.
     PMID18326712.
 8.  ^ abBengtsson, Boel; Olsson, Jonny; Heijl, Anders; Rootzén, Holger (27 May
     2009). 'A new generation of algorithms for computerized threshold
     perimetry, SITA'. Acta Ophthalmologica Scandinavica. 75 (4): 368–375.
     doi:10.1111/j.1600-0420.1997.tb00392.x.
 9.  ^ abSzatmáry, Gabriella (1 September 2002). 'Can Swedish Interactive
     Thresholding Algorithm Fast Perimetry Be Used as an Alternative to Goldmann
     Perimetry in Neuro-ophthalmic Practice?'. Archives of Ophthalmology. 120
     (9): 1162. doi:10.1001/archopht.120.9.1162.
 10. ^'Vic Driving Vision Standards'. Optometry Australia. Optometry Australia.
     Archived from the original on 2016-04-18.
 11. ^'Visual impairment'. VicRoads. State Government of Victoria. 2015.
     Archived from the original on 2019-02-28.
 12. ^ abcdefghijklArtes, Paul H (2012). Humphrey Field Analyzer II-i series
     User Manual. Carl Zeiss Meditec.
 13. ^Bengtsson, B; Heijl, A (2000). 'False-negative responses in glaucoma
     perimetry: indicators of patient performance or test reliability?'.
     Investigative Ophthalmology and Visual Science. 41 (8): 2201–2204.
 14. ^McKendrick, Allison M.; Denniss, Jonathan; Turpin, Andrew (August 2014).
     'Response times across the visual field: Empirical observations and
     application to threshold determination'. Vision Research. 101: 1–10.
     doi:10.1016/j.visres.2014.04.013. PMID24802595.
 15. ^Johnson, Chris A; Keltner, John L; Cello, Kimberly E; Edwards, Mary; Kass,
     Michael A; Gordon, Mae O; Budenz, Donald L; Gaasterland, Douglas E; Werner,
     Elliot (March 2002). 'Baseline visual field characteristics in the ocular
     hypertension treatment study'. Ophthalmology. 109 (3): 432–437.
     doi:10.1016/S0161-6420(01)00948-4.
 16. ^ abWyatt, Harry J.; Dul, Mitchell W.; Swanson, William H. (March 2007).
     'Variability of visual field measurements is correlated with the gradient
     of visual sensitivity'. Vision Research. 47 (7): 925–936.
     doi:10.1016/j.visres.2006.12.012. PMC2094527. PMID17320924.
 17. ^Cubbidge, R (2012). 'Essentials of visual field assessment'. The Optician.
     243 (6356): 14–16. ProQuest1027770159.
 18. ^Chen, Yi-Hao; Wu, Jian-Nan; Chen, Jiann-Torng; Lu, Da-Wen (2008).
     'Comparison of the Humphrey Field Analyser and Humphrey Matrix Perimeter
     for the Evaluation of Glaucoma Patients'. Ophthalmologica. 222 (6):
     400–407. doi:10.1159/000154203.
 19. ^Stamper, Robert L; Lieberman, Marc F; Drake, Michael V (2009).
     Becker-Shaffer's diagnosis and therapy of the glaucomas (8th ed.).
     [Edinburgh]: Mosby/Elsevier. ISBN978-0-323-02394-8.
 20. ^ abIshiyama, Y.; Murata, H.; Mayama, C.; Asaoka, R. (11 November 2014).
     'An Objective Evaluation of Gaze Tracking in Humphrey Perimetry and the
     Relation With the Reproducibility of Visual Fields: A Pilot Study in
     Glaucoma'. Investigative Ophthalmology & Visual Science. 55 (12):
     8149–8152. doi:10.1167/iovs.14-15541. PMID25389198.
 21. ^Horton, M. (2015). '10 tips for improving visual fields: perimetry may
     seem like second nature, but these recommendations can help you obtain
     better results by refining your understanding of the technology'. Review of
     Optometry. 152 (4): 62.
 22. ^Kuzhuppilly N, Patil S, Dev S, Deo A. Reliability of Visual Field Index in
     Staging Glaucomatous Visual Field Damage. Journal of Clinical & Diagnostic
     Research. 2018 Jun 1;12(6): NC05-NC08
 23. ^Saigal, Rahul. 'Learning Effects and Artefacts in Automated
     Perimetry'(PDF). Association Of Optometry Ireland.
 24. ^Donahue, Sean. P. (1998). 'Lens Holder Artifact Simulating Glaucomatous
     Defect in Automated Perimetry'. JAMA Ophthalmology. 116 (12): 1681–1683.
     doi:10.1001/archopht.116.12.1681. PMID9869806.

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