OPT505: Interpreting SITA Results

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Questions and Answers

What appearance of the optic nerve head suggests potential issues related to stroke or trauma?

Myopic

Swollen (correct)

Cupped (correct)

Tilted

In which situation would fixation loss during visual field testing be considered unreliable?

More than 20% fixation loss (correct)

Exactly 15% fixation loss

More than 10% fixation loss

Less than 10% fixation loss

What is a likely consequence of having more than 15% false negatives during a visual field test?

The patient is focused

The patient is tired (correct)

The test is reliable

The patient's response is accurate

What is the primary reason for conducting catch trials during visual field testing?

To check for false responses Signup and view all the answers

Which characteristic is associated with unreliable visual field data if pupils are small or dry?

Gaze tracking issues Signup and view all the answers

Which visual field testing scenario would most likely trigger false positives?

Patient is anxious and trying to perform well Signup and view all the answers

What might a sudden drop in visual acuity (VA) indicate?

A serious underlying condition Signup and view all the answers

What kind of retinal appearance would suggest the presence of macular pathology?

Presence of exudates Signup and view all the answers

What does SITA stand for in the context of automated perimetry?

Swedish Interactive Threshold Algorithm Signup and view all the answers

What is the main advantage of using a threshold test compared to a supra-threshold test?

Threshold tests provide detailed sensitivity to subtle losses. Signup and view all the answers

How does SITA improve the efficiency of the visual field test?

By combining Bayesian approaches with adaptive intervals. Signup and view all the answers

Which of the following factors is NOT crucial for identifying reliable results in automated perimetry?

Frequency of visual tests performed Signup and view all the answers

Which of the following best describes the testing pattern used in SITA 24-2?

Straddles the horizontal and vertical meridians with 24 tests. Signup and view all the answers

What method does SITA use to predict the next response during the test?

Continuously estimates based on patient age and adjacent thresholds. Signup and view all the answers

What is a noted challenge when finding the threshold in visual field tests?

Finding the threshold can be time-consuming. Signup and view all the answers

What is a characteristic that distinguishes SITA from other methods in visual field testing?

It allows for adaptive testing based on previous results. Signup and view all the answers

What is a primary advantage of the ZATA testing method compared to the SITA standard?

It requires less accurate prior patient data. Signup and view all the answers

Which characteristic is unique to the SITA fast compared to SITA standard and ZATA?

It provides quicker results with less reliability. Signup and view all the answers

Which statement is true regarding the testing pattern used in both SITA and ZATA?

Both utilize the 24-2 and 30-2 patterns. Signup and view all the answers

What is a disadvantage of the SITA standard compared to ZATA?

It requires more time to complete. Signup and view all the answers

How does the algorithm of ZATA differ from SITA fast?

ZATA requires prior patient data for threshold estimation. Signup and view all the answers

In terms of patient fatigue, which statement is accurate?

SITA fast is designed to decrease patient fatigue. Signup and view all the answers

Which feature sets the ZATA method apart regarding the detection of defects?

It identifies shallow defects with less depth. Signup and view all the answers

What is the significance of the working distance for the trial lens mentioned?

It affects the accuracy of the test results. Signup and view all the answers

What does a Positive Shape Deviation (PSD) value greater than +2.00 dB indicate?

It signifies localized changes in the visual field. Signup and view all the answers

What classification does the Glaucoma Hemifield Test (GHT) NOT include?

Unusual pattern Signup and view all the answers

Which factor should NOT be considered when analyzing visual field tests for glaucoma?

The patient's favorite color Signup and view all the answers

What does 'Borderline' indicate in the context of GHT results?

Areas of difference are not statistically significant. Signup and view all the answers

How should the visual field tests be compared to evaluate disease progression effectively?

Analyze six or more previous tests. Signup and view all the answers

In interpreting the total deviation plot, what does it signify?

The degree of deviation after accounting for media opacities. Signup and view all the answers

What is the main goal when evaluating focal defects in visual fields?

To identify possible underlying neurological damage. Signup and view all the answers

What does the Total Deviation plot indicate in visual field analysis?

The variation from age-matched normal values. Signup and view all the answers

What is indicated when Mean Deviation (MD) values are greater than ±2.00 dB?

They usually indicate an abnormal visual field. Signup and view all the answers

What additional assessments should be made if abnormal visual fields are observed?

Review previous visual field tests for progression. Signup and view all the answers

What does a low Pattern Standard Deviation (PSD) signify in a visual field test?

The visual field is relatively normal. Signup and view all the answers

In visual field testing, what does the probability (P) values on deviation plots indicate?

The likelihood of deviations occurring by chance. Signup and view all the answers

How is Global Indices specifically used to evaluate diffuse loss in visual fields?

By measuring the average values against population normal values. Signup and view all the answers

When interpreting deviation plots, why is it important to assess both Total Deviation and Pattern Deviation?

To identify whether the defects are diffuse or focal. Signup and view all the answers

What effect does the presence of cataract have on Mean Deviation (MD) values?

It makes MD values more negative, indicating greater loss. Signup and view all the answers

What characteristic of a visual field defect is reflected by the shape of Pattern Deviation plots?

The true configuration of the defect. Signup and view all the answers

What does the top plot specifically represent in terms of visual field analysis?

The difference in dB between numeric scale values and age-corrected normal values Signup and view all the answers

What is indicated by a Pattern Standard Deviation (PSD) value greater than +2.00 dB?

It indicates potential focal loss Signup and view all the answers

What does a negative Mean Deviation (MD) typically indicate in the presence of cataracts?

Decreased average threshold values relative to normal Signup and view all the answers

What is the primary use of the Glaucoma Hemifield Test (GHT)?

To compare visual fields above and below the horizontal meridian for detecting glaucoma Signup and view all the answers

In visual field analysis, what does a ‘borderline’ GHT result signify?

Some differences are present, but are not statistically significant Signup and view all the answers

What is the significance of P values in visual field analysis?

They measure the likelihood of a defect being significant. Signup and view all the answers

How does one differentiate between focal loss and diffuse loss in visual field plots?

By comparing both top and bottom plots together Signup and view all the answers

What does the bottom plot in visual field analysis represent?

It indicates the probability of significant visual defects occurring. Signup and view all the answers

Study Notes

Nut-Free Zone

Images show various foods and a stop sign indicating a nut-free zone.
The image suggests an area that prohibits nuts.

Lecture Recording

The lecture is being recorded and will be available via a Panopto block.
Students can ask questions, and comments might appear on the recording.
Students can ask the lecturer to pause the recording if they do not want their questions or comments to be recorded.

Interpreting SITA Plots

The lecture is about interpreting SITA plots.
The lecturer is Ellie Livings.
The course is OPT505.

Intended Learning Outcomes

Students will understand SITA and ZATA.
Students will learn how to set up parameters for automated perimetry.
Students will understand factors affecting test results.
Students will know which testing program to choose.
Students will learn to identify reliable results.
Students will learn to interpret results.
Students will work through case scenarios.

Vision Field Tests

Images of eye chart and an eye care specialist.
A speech bubble says "Sir, we need to do a fields test."
The text involves visual field tests.

Recap

The notes cover the frequency of seeing curves, thresholds, and supra-thresholds.

Threshold Test

Supra-threshold tests are often screening tests.
Threshold tests offer more detail and are sensitive to subtle loss.
Threshold tests are good for monitoring conditions and early detection.
Performing a threshold test may take a long time.

Humphrey Field Analyzer (HFA)

The HFA is the gold standard for glaucoma field evaluation.
The SITA test is common in glaucoma research.
Specific data points are supplied for this test from an HFA machine, such as fixation monitor, fixation target, fixation losses, false positive errors, false negative errors, and more.

Testing Features (HFA)

The HFA includes threshold test libraries (central and peripheral patters and strategies).
It has screening test libraries (central and peripheral patterns and strategies).
Includes screening test modes, and specialty test libraries.
Offers Esterman Monocular, Esterman Binocular, and Superior 36 and Superior 64 tests.
Available kinetic testing and custom testing.
Includes different stimulus/background colors.

SITA (Swedish Interactive Threshold Algorithm)

SITA is a Swedish Interactive Threshold Algorithm.
The test quickly determines the threshold and uses the staircase algorithm.
It avoids false-positive catch trials and uses variable inter-stimulus intervals.
SITA is done by starting closer to the threshold.

What is SITA?

SITA continually estimates the next response based on the current px age and adjacent thresholds.
It's faster than other threshold methods, and causes less patient fatigue.
It provides increased reliability without requiring a full threshold test.

Henson 9000, ZATA

The Henson 9000 features ZATA (Zippy adaptive threshold algorithm).
The image shows a device and software related to this machine.

SITA v ZATA

SITA offers standard and fast tests, using white-on-white stimuli, and 4-2dB steps, estimating sensitivity.
ZATA uses a zippy adaptive threshold algorithm, and uses prior data, focusing on areas of loss.
ZATA also uses a white-on-white visual field test format.

Glaucoma Hemifield Test Results (SITA)

A table shows the results of glaucoma hemifield tests using SITA strategies, including different classifications (outside normal limits, borderline, within normal limits, etc.).
Numbers indicate the success or failure of each of the procedures.

Set-Up

Patients can get easily fatigued, especially if the test takes a long time.
Perimetry effectiveness decreases if the patient’s reliability/concentration is poor.
Consider noisy/crowded environments.
Proper setup is very important for testing.

Trial Lens Selection

Guidelines for selecting trial lenses are provided (use tables to calculate spherical equivalent).
Important for accurate testing by considering visual field and refractive errors.

SITA 24-2

This test takes 2-5 minutes.
It tests 54 points (in central 24 degrees) with 6-degree spacing.
The grid of points straddles nasal/temporal mid-lines.

Interpreting Fields: Artefacts

Media opacities can cause patchy defects, general depression, and mask small defects.
Uncorrected refractive errors can cause depression over the whole field.
Facial characteristics, like ptosis or large noses, can affect testing.
Lens rim artifacts can create specific losses.

Interpreting the Fields: SITA 24-2

Includes the test's name, what is done, reliability indices (how accurate).
Mentions fixation loss, false negatives, false positives, test duration, global indices (are fields normal), mean deviation (MD), pattern standard deviation (PSD), and total and pattern deviation plots.

Reliability: Fixation

Fixation tracking is unreliable if fixation loss is over 20%.
Monitoring the blind spot during testing is crucial.
Gaze tracking methods are also used for monitoring the patient's eye position and blinking frequency during testing.

Reliability: Catch Trials

False positives occur when the patient reacts to a stimulus that was not presented.
Patients who are "trigger-happy" (many false positives) often struggle with the test and need reassurance.
If more than 15% of trials are false positives or if fixation losses are over 33%, the test is unreliable.

Deviation Plots

Total deviation plots show the difference between measured and normal values.
Pattern deviation plots show the shape and uniformity of the visual field.
Analyzing both plots is necessary for identifying focal defects.

Global Indices - Diffuse Loss (Mean Deviation (MD))

MD is the difference between average threshold values and normal thresholds.
Values above ±2.00 dB are usually abnormal.
P-values are used to determine the significance of the detected diffuse defect.
It is important to compare total and pattern deviation plots to see if focal defects are present.

Global Indices - Focal Loss (Pattern Standard Deviation (PSD))

PSD is an index for non-uniformity, or localized focal defects (within visual field).
Values above +2.00 dB are usually abnormal.
P-values indicate the significance of the focal defect.
PSD increases in the presence of a focal loss.

Global Indices - Glaucoma Hemifield Test (GHT)

GHT compares points above and below the horizontal meridian to evaluate glaucoma.
Visual field data can classify results as within normal limits, borderline, or outside normal limits based on significant differences between tested areas.
GHT is a very dependable index, but it's only suitable for detecting glaucoma field defects in the visual field.

What Can We Say?

This section summarizes the findings from visual field tests.
Questions about which eye is more suspicious are asked.

Background Learning

SITA algorithm, ZATA (Zippy adaptive threshold algorithm) details and explanations are included.
Discussions about monitoring and detecting early glaucoma are involved in the notes.

Real Case Example

Notes on identifying reliable fields and continuing with analysis of test results are included

Interpreting the Data: Reliability

Review of reliable fields to ensure there are no false positives (over 15%), fixation losses (over 33%), and issues like lens rim artifacts, or uncorrected ptosis in the patient's field.
Evaluate data if fields seem reliable; otherwise, the test may need to be repeated or further evaluated.

Interpreting the Data

Data interpretation involves analysing the shape of visual field defects; using the visual field pathway chart is necessary.
Comparing visual fields over time helps detect progression of visual field defects.
Six or more tests are necessary for evaluating disease progression for significant analysis; considering findings from other tests and imaging is essential.

Clinical Observations

Review of a patient's medical history and symptoms are involved, including family history (glaucoma, cataracts).
Medical review covers onset of symptoms, which eye is affected, pain symptoms, and any relevant medical conditions (stroke, diabetes, etc.).
Information about clinical findings is included: ONH appearance, media opacities, pupil size, retinal appearance, and refractive findings (including amblyopia, VA, and color vision).
Details include medication use (e.g., stomach tablets, antibiotics) and activities (walking dogs, computer work).
Refractive errors and eye examinations (e.g., retinoscopy, amplitude of accommodation, and subjective distance refraction) are also included.

Additional Notes

The notes highlight aspects like visual acuity, pupils, ptosis, facial characteristics, media, and ONH examinations.
Details about how not to catch rubbish/avoid mistakes are included.
Notes cover various testing methods and how to evaluate the results.
Important aspects of patient monitoring for detecting early glaucoma and other visual field defects are emphasized..

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Description

This quiz focuses on the interpretation of SITA plots as covered in the OPT505 course, instructed by Ellie Livings. Students will explore parameters for automated perimetry and understand factors affecting test results, as well as identify reliable outcomes through practical case scenarios.