TN 3 (05-10)

# DI 24535.006 Evaluation of Visual Impairments – Medical Equivalence Using the Humphrey Field Analyzer (HFA) 30-2 Calculator for Listings 2.04 and 102.04

## A. Background

We evaluate the loss of visual efficiency under listings 2.04 and 102.04. These listings require a visual efficiency of the better eye of 20 percent or less after best correction. We calculate the visual efficiency percentage by multiplying the visual acuity (VA) efficiency by the visual field (VF) efficiency and converting the decimal to a percentage. For a visual disorder to **meet** listing 2.04 or 102.04, we require results from **kinetic** perimetry to determine the VF efficiency. We cannot use results from automated static threshold perimetry to determine that a visual disorder **meets** listing 2.04 or 102.04. We may, however, use the results from an acceptable and reliable HFA 30-2 test (which is an automated static threshold VF test, see DI 24535.005B) in the **“****Humphrey Field Analyzer (HFA) 30-2 Calculator for Listings 2.04 and 102.04****”** to determine **medical equivalence**. The calculator computes a visual efficiency **value** that is comparable to the visual efficiency **percentage** required by listings 2.04 and 102.04.

## B. Explanation of the calculator

A National Research Council study of visual disorders provided the mathematical formula for the calculator. The formula gives equal weight to VA and VF, and combines the person’s VA and VF to compute an overall measure of visual impairment. The common logarithm (log) of the minimum angle of resolution (MAR), called the logMAR, plus the absolute value of the MD divided by 22 (logMAR + |MD|/22) equals the overall measure of the person’s visual impairment. Each eye is calculated separately. When the values computed by the calculator equal or exceed 1.0 in both eyes, the visual disorder medically equals the listing.

**REFERENCE:** National Research Council. (2002). **Visual Impairments: Determining Eligibility for Social Security Benefits.** Committee on Disability Determination for Individuals with Visual Impairments. Lennie, P., and Van Hemel, S. B. (Eds.). Division of Behavioral and Social Sciences and Education. Washington, D.C.: National Academy Press.

## C. When to use the calculator

You may use the calculator to determine if a visual disorder medically equals listings 2.04 and 102.04 based on VA testing using Snellen methodology and acceptable and reliable HFA 30-2 VF testing. The calculator is located on the intranet website for the Office of Disability Programs under Listings of Impairments, Special Senses and Speech, Calculator Tools .

**NOTE:** Do not use results from HFA 24-2 VF testing in this calculator.

## D. Procedure for using the calculator

### 1. Step 1 – VA impairment

Enter the Snellen fraction denominators for the **best-corrected** VA in the left and right eyes.

**NOTE:** If the person’s best-corrected VA in either eye cannot be expressed in Snellen notation (for example, best-corrected VA is counts fingers (CF) or hand motion (HM)), substitute 20/200 for the VA and use 200 in the calculator for the denominator value.

### 2. Step 2 – VF impairment

Enter the mean deviation (MD) values from the HFA 30-2 results for the left and right eyes.

### 3. Step 3 – Visual efficiency results

The calculator will display one of the following results:

“Medically Equals Listing 2.04 or 102.04,” with a green background

“Does Not Medically Equal Listing 2.04 or 102.04,” with a red background

**IMPORTANT:**These statements only refer to the results of this calculator. Other ways to determine medical equivalence may still apply as described in DI 24505.015B.2.

## E. References

DI 24505.015, Finding Disability on the Basis of Medical Factors Alone

DI 24535.005, Titles II and XVI: Evaluating Visual Field Loss Using Automated Static Threshold Perimetry — SSR 07-01p