2 - VF testing patterns and strategies

what is threshold kinetic testing?

outlines field or defect shape → displayed as isopters

can be manual or automated

When is threshold kinetic testing used?

1. testing peripheral vision quickly and characterizing its spatial extent

2. driving testing

3. post-stroke testing → testing pt with significant VF loss

4. disability determination

5. kids or patients with difficulty completing static testing

What are the levels of static screeners?

Single Intensity Strategy

Threshold-Related Strategy

3 Zone Strategy

Quantify Defects Strategy

What is the threshold-related strategy screener test?

uses stimulus 6 dB brighter than expected threshold or uses a dB that 95% of the population can see

how to record results for threshold-related strategy screener test?

if seen on 1st try → recorded as seen and not test again

if missed on 1st try → point is tested again

-if seen on repeat test → recorded as seen

-if missed on repeat tests → recorded as missed

Which static screener test is most common?

Threshold-Related Strategy

What is the 3 Zone Strategy screener test?

uses 3 symbols for no defect, relative defect, and absolute defect

What is the Quantify Defects Strategy screener test?

missed screening stimuli are thresholded

what do you do when defects are found with screening strategies?

don't repeat a screening → proceed to a threshold strategy

When do you progress to a threshold test from a screener?

If ≥2 adjacent points are missed

If ≥ 1 misses within 20º of fixation

If central vision is ≤26 dB

what is the basic testing setup for Humphrey Threshold testing?

stimulus duration: 200 ms

Goldmann size: III

stimulus intensity: varied

What are the two most common testing patterns (Humphrey and Octopus)?

24-2

30-2

what is the difference between 24-2 and 30-2?

24-2 tests less points and a smaller area but captures most of the same info → 24-2 removed outer ring of test points except nasal-most 2

When is a 10-2 VF test useful?

a small central scotoma is suspected

OR

specific macular testing is desired

What is a 24-2C (Humphrey)?

24-2 with more (10) macular points based on NFL physiology

What is the Octopus G-pattern?

central 30º test based of NFL physiology

What is the Octopus G-pattern closest to?

Humphrey 24-2C

What is the Octopus M-pattern?

like a 10-2 but with more emphasis near fovea

Visual Field testing uses what psychometric procedure?

staircase

What is the "Humphrey Full threshold" algorithm?

4 dB staircase followed by a 2dB staircase

what is the Humphrey SITA (Swedish Interactive Testing Algorithm)?

reduced number of points shown without a reduction in data quality

Humphrey SITA standard strategy is similar to what Octopus strategy?

Octopus Dynamic strategy

Humphrey SITA Fast strategy is similar to what Octopus strategy?

Octopus TOP strategy

Why is the SITA algorithm faster?

1. starts testing near threshold

2. adjusts pace according to reaction time

3. stops when uncertainty decreases to a given level

4. recalculates all threshold values following testing

what is a maximum likelihood procedure?

using all previous responses to determine likely threshold

How does the Humphrey SITA standard algorithm work?

uses previous responses to determine most likely threshold at that point → 4dB then 2 dB staircase

How does the Humphrey SITA fast algorithm work?

also uses previous responses to determine most likely threshold at that point → only uses a 4dB staircase at most points

How does Humphrey SITA fast compare to SITA standard?

takes about 2/3 of the time → but re-test reliability is a bit worse

What is the most common VF testing pattern and strategy for clinic?

24-2 TOP → Octopus at OSU

24-2 SITA Fast (or 24-2C SITA Faster) → HFA at other sites

What is the recommendation regarding SITA faster?

use for most patients bc the clinic flow and patient compliance far outweigh the small difference in repeatability

How does SITA faster work so fast?

presents initial stimuli at the expected threshold value, which is much lower intensity than in SITA standard or fast

no blind spot check

What are the main disadvantages to SITA faster?

sometimes hard to explain to new patients as the test points are very dim from the start

poorer re-test variability