November 19, 2007
 
Memorandum for RSB Staff
 
FROM: Mike Merrick
 
SUBJECT: Use of the SSA Kinetic Test to Determine Visual Efficiency
 
For some time there has been a problem with establishing visual eligibility through the use of RSB’s 'visual efficiency' definition. The problem has been that in order to calculate visual efficiency, you need test results which define the visual field in degrees at the eight meridians (the eight points around the perimeter of the visual field, all 45 degrees apart). These results were a normal part of the examination performed with the Goldmann perimeter, a manual device for testing visual fields. However, almost all eye care professionals have gone to the use of the Humphrey Field Analyzer, an automated tester which does very detailed tests and reports the results via computerized output. In many cases the physician’s office does not have an available Goldmann device, or the personnel trained in its operation.
 
In February, 2007 the Social Security Administration (SSA) adopted a final regulation that changed its standards of eligibility for visual fields (excerpts of this regulation are located below). In this final regulation, SSA identified the Humphrey Field Analyzer as an acceptable device for determining visual field perimeters, and adopted the SSA Test Kinetic for determination of the perimeter of the visual field. The SSA Test Kinetic provides the results in the form of a chart (see Figure 1) that identifies the degrees of field at each of the eight meridians (the information we need to complete our visual efficiency worksheet). Adding the sum of the degrees of field at all eight meridians gives you a score between 0 – 500 that you compare to the visual field percentage worksheet (see Fig. 2 or go to http://dss.mo.gov/fsd/rsb/manual/vrman/forms/visual_field_percent.xls)
to convert the score to a percentage, which you then enter on the visual efficiency worksheet (see Fig. 3 or http://dss.mo.gov/fsd/rsb/manual/vrman/forms/visual_efficiency.xls) Also, if you look at the lower left-hand corner of the SSA Test Kinetic chart, you will find an SSA Efficiency Score that you can simply enter as the visual field percentage (they've already done the adding/subtracting and applied it to the chart) for that eye, saving you the step of adding all the meridians and going to the chart.
 
One characteristic of the SSA Test Kinetic provides less information than the Goldmann device. The Goldmann maps the entire visual field, including areas where there is no vision that are surrounded by vision (called 'scotoma' or 'scotomata'). The SSA Test Kinetic identifies only the outer perimeter of vision; anything inside that perimeter is not tested. So, the SSA Test Kinetic is not useful in mapping the areas of the visual field inside the perimeter. If you suspect central field defects, or scotomata inside that perimeter (for example, in a case where the client has Retinitis Pigmentosa), you should request specific field testing to identify them, i.e., the Humphrey 24-2 or 30-2. The SSA Test Kinetic is only used for one purpose: identifying the farthest perimeter of visual fields at the eight meridians for visual efficiency purposes. Of course, if an eye doctor has the equipment and will perform the Goldmann field test, those results are still acceptable and will still provide the information we require.
 
Please remember that when you are considering eligibility testing for a client who reports having reduced visual fields, or that you suspect will not be eligible without considering visual efficiency, you should request that the office providing the testing use the SSA Test Kinetic. It should be available on all Humphrey Field Analyzers newer than 1994, although your provider might need to be reminded of its existence. With the new test criteria from SSA, though, I would suspect they will be very quick to master its use.
 
MM

EXCERPT FROM SSA FINAL REGULATION FOR VISUAL ELIGIBILITY:
 
The National Research Council (NRC), in its 2002 report, Visual Impairments: Determining Eligibility for Social Security Benefits (hereinafter, the "NRC report"), recommended that "the current SSA standard [for assessing visual field loss] should be revised so that disability determinations are based on the results of automated static projection perimetry rather than Goldmann (kinetic, nonautomated)visual fields." (Citations for the NRC report and other sources cited in this preamble are available in the NPRM (70 FR at 48348).) These final rules partially adopt this recommendation by providing that we will use visual field measurements obtained with an automated static threshold perimetry test performed on a perimeter that meets our requirements. However, we have decided that we will also continue to use visual field measurements obtained with Goldmann or other kinetic perimetry as these measurements are comparable to those obtained with automated static threshold perimetry.  
In final 2.00A6a(ii), we explain that, when we need to measure the extent of your visual field loss, we will use visual field measurements obtained with an automated static threshold perimetry test performed on a perimeter that meets our requirements. We adopted as our requirements the criteria recommended in the NRC report. We cite the Humphrey Field Analyzer as an example of an acceptable perimeter because the NRC report cited it, and the Humphrey Field Analyzer is the most widely used automated perimeter in the United States to perform this type of test.  
The NRC report also cited the Octopus perimeter as another example of an automated perimeter that meets the criteria set out in its recommendations. We have not included the Octopus perimeter as an example of an acceptable perimeter in final 2.00A6a(ii), because it is not our intention to list in these rules every acceptable automated perimeter and the Octopus perimeter is not widely used in the United States. However, we will accept findings from the Octopus perimeter or any other automated perimeter that satisfies the requirements of final 2.00A6a(ii).  
We contracted with West Virginia University to conduct research to determine whether the Humphrey "SSA Test Kinetic" is comparable to Goldmann perimetry. This research, which was completed in April 2000, showed that the Humphrey "SSA Test Kinetic" is comparable to Goldmann perimetry, except that the Humphrey "SSA Test Kinetic" does not identify scotomata, that is, non-seeing areas in the visual field surrounded by seeing areas. Therefore, in the NPRM, we proposed that if we needed additional information because your visual disorder had progressed to the point where it was likely to result in a significant limitation in the central visual field, such as a scotoma, we would supplement the automated kinetic perimetry with the results of a Humphrey 30-2 or comparable test. There were public comments questioning this guidance. In response to those comments, we have clarified this section to state that we will not use the results of automated kinetic testing to assess your visual field loss in this situation. Instead, we will assess your visual field loss with automated static threshold perimetry or with manual kinetic perimetry.  
From PART 404--FEDERAL OLD-AGE, SURVIVORS AND DISABILITY INSURANCE (1950- )  
6. How do we measure visual fields?
a. Testing for visual fields.
(i) We generally need visual field testing when you have a visual disorder that could result in visual field loss, such as glaucoma, retinitis pigmentosa, or optic neuropathy, or when you display behaviors that suggest a visual field loss.

(ii) When we need to measure the extent of your visual field loss, we will use visual field measurements obtained with an automated static threshold perimetry test performed on a perimeter, like the Humphrey Field Analyzer, that satisfies all of the following requirements:

A. The perimeter must use optical projection to generate the test stimuli.
B. The perimeter must have an internal normative database for automatically comparing your performance with that of the general population.
C. The perimeter must have a statistical analysis package that is able to calculate visual field indices, particularly mean deviation.
D. The perimeter must demonstrate the ability to correctly detect visual field loss and correctly identify normal visual fields.
E. The perimeter must demonstrate good test-retest reliability.
F. The perimeter must have undergone clinical validation studies by three or more independent laboratories with results
published in peer-reviewed ophthalmic journals.

(iii) The test must use a white size III Goldmann stimulus and a 31.5 apostilb (10 cd/m\2\) white background. The stimuli locations must be no more than 6 degrees apart horizontally or vertically. Measurements must be reported on standard charts and include a description of the size and intensity of the test stimulus.

(iv) To determine statutory blindness based on visual field loss (2.03A), we need a test that measures the central 24 to 30 degrees of the visual field; that is, the area measuring 24 to 30 degrees from the point of fixation. Acceptable tests include the Humphrey 30-2 or 24-2 tests.

(v) The criterion in 2.03B is based on the use of a test performed on a Humphrey Field Analyzer that measures the central 30 degrees of the visual field. We can also use comparable results from other acceptable perimeters, for example, a mean defect of 22 on an acceptable Octopus test, to determine that the criterion in 2.03B is met. We cannot use tests that do not measure the central 30 degrees of the visual field, such as the Humphrey 24-2 test, to determine if your impairment meets or medically equals 2.03B.

(vi) We measure the extent of visual field loss by determining the portion of the visual field in which you can see a white III4e stimulus. The "III" refers to the standard Goldmann test stimulus size III, and the "4e" refers to the standard Goldmann intensity filters used to determine the intensity of the stimulus.

(vii) In automated static threshold perimetry, the intensity of the stimulus varies. The intensity of the stimulus is expressed in decibels (dB). We need to determine the dB level that corresponds to a 4e intensity for the particular perimeter being used. We will then use the dB printout to determine which points would be seen at a 4e intensity level. For example, in Humphrey Field Analyzers, a 10 dB stimulus is equivalent to a 4e stimulus. A dB level that is higher than 10 represents a dimmer stimulus, while a dB level that is lower than 10 represents a brighter stimulus. Therefore, for tests performed on Humphrey Field Analyzers, any point seen at 10 dB or higher is a point that would be seen with a 4e stimulus.

(viii) We can also use visual field measurements obtained using kinetic perimetry, such as the Humphrey "SSA Test Kinetic" or Goldmann perimetry, instead of automated static threshold perimetry. The kinetic test must use a white III4e stimulus projected on a white 31.5 apostilb (10 cd/m\2\) background. In automated kinetic tests, such as the Humphrey "SSA Test Kinetic," testing along a meridian stops when you see the stimulus. Because of this, automated kinetic testing does not detect limitations in the central visual field. If your visual disorder has progressed to the point at which it is likely to result in a significant limitation in the central visual field, such as a scotoma (see 2.00A8c), we will not use automated kinetic perimetry to evaluate your visual field loss. Instead, we will assess your visual field loss using automated static threshold perimetry or manual kinetic perimetry.

(ix) We will not use the results of visual field screening tests, such as confrontation tests, tangent screen tests, or automated static screening tests, to determine that your impairment meets or medically equals a listing or to evaluate your residual functional capacity. However, we can consider normal results from visual field screening tests to determine whether your visual disorder is severe when these test results are consistent with the other evidence in your case record. (See Sec. 404.1520(c), 404.1521, 416.920(c), and 416.921.) We will not consider normal test results to be consistent with the other evidence if either of the following applies: A. The clinical findings indicate that your visual disorder has progressed to the point that it is likely to cause visual field loss, or B. You have a history of an operative procedure for retinal detachment.    
 

 
FIGURE 1: Exemplar SSA Test Kinetic Chart

Figure 2. Visual Field Percentage Worksheet (Partial)

Figure 3. Visual Efficiency Worksheet (Exemplar)