Rating Schedule

INTRODUCTION

Visual impairment results from a deviation from normal in one or more of the three primary functions of the eye.

1. Near and far acuity

2. Visual fields

3. Motility (presence of diplopia)

The primary functions are not equally important, but perfect vision requires the coordination of all three.

Second and subordinate functions are:

1. Color vision

2. Light/dark adaptation

3. Accommodation

4. Iridoplegia

5. Entropion

6. Ectropion

7. Epiphora

8. Lagophthalmos

9. Scarring (globe)

If these secondary impairments are present and do not contribute to the impairment of primary functions, they must be evaluated independently under the appropriate body system and the respective impairments added to the impairment of the visual system.

Tertiary impairments must be calculated as contributing an additional 5 to 10% impairment to the involved eye. Such are:

1. Vitreous opacities

2. Nonreactive pupil

3. Light-scattering abnormalities

Skeletal or soft-tissue abnormalities that do not alter ocular function should be considered individually and may contribute up to 10% of whole-person impairment.

LOSS OF VISION

Clearly distinguish between complete and partial loss of vision and rate complete loss of vision in both eyes as 85%, while complete loss of vision in one eye when the vision in the opposite eye is normal is rated at 24%.

For partial loss of vision, rules to be followed in determining impairment include:

1. All medically acceptable attempts to correct must have been exhausted.

2. Determination must await 6 months freedom from all external signs of inflammation.

3. Determination to be deferred 12 months in case of

a. Extrinsic muscle disturbance

b. Retinal injury

c. Sympathetic ophthalmia

d. Traumatic cataract

4. Testing is to be performed with corrective lenses unless otherwise stipulated.

PRIMARY COORDINATE FACTORS

The primary functions are:

1. Central Visual Acuity (CVA)

2. Visual Field Efficiency (VFE)

3. Ocular Motility (OM)

Maximum Limits for each Coordinate Factor—MPPI states the standards for testing and the normal limits for each factor. The standards prescribed are identical to those established in the AMA document.

Central visual acuity refers to the ability to recognize letters that subtend an angle of five minutes, each part of which subtends an angle of one minute at the distance viewed. The normal, or 100%, VA is considered to be 20/20 Snellen or AMA chart or 14/14/AMA card for near vision. These standards refer to a chart imprinted with block letters or numbers in gradually decreasing sites, identified by distances at which they are normally visible. It is used in testing visual acuity. The numerator is the test distance in feet. The denominator is the distance at which the smallest letter discriminated by the patient would subtend five minutes of arc.

Visual Field Efficiency—The maximum, or normal, visual field is defined as 500 degrees, which is the sum of degrees in the eight principal meridians from the central point of fixation to the outermost limits of visual perception, using a 3 mm white target at 33 centimeters. 100%, or normal, VFE is visual extension from central point of fixation in the following eight principal meridians.

1. Outward ... 85°

2. Down and outward ... 85°

3. Down ... 65°

4. Down and in ... 50°

5. Inward ... 60°

6. In and up ... 55°

7. Upward ... 60°

8. Up and out ... 55°

Total ... 500°

The minimum of the visual field is defined as 5% concentric central contraction.

Ocular Motility—Maximum ocular motility is present if there is normal ocular motor coordination with no diplopia in all parts of the field of binocular fixation. The minimum limit of ocular motility is defined as diplopia in all parts of the field of binocular fixation, or absence of binocular motor coordination.

MEASURE AND COMPUTATION OF LOSS

Central Visual Acuity

a. Near and distance vision will be measured separately with correction.

b. Snellen chart for distance and the AMA chart for near vision will be used.

c. Illumination will be at least five foot candles

d. Loss of central vision will be computed from a table provided, using the corrected near and far vision for each eye. The upper figure of the two figures provided will be the percentage loss of central vision for that eye. In the case of aphakia or pseudoaphakia, the lower of the two figures will be used.

Visual Field

a. Perimetric standards for determination are as previously described, except that in cases of aphakia the white disc shall be 6mm rather than 3mm.

b. The amount of radial contraction shall be determined in the eight principal meridians, as defined.

The visual field loss of each eye, expressed as a percentage, is the sum of the degrees of field vision loss in the principal meridians divided by 500.

c. If the central contraction is 5 degrees, the loss is 100%

d. If the field impairment is irregular and not fairly disclosed by the principal meridians, the loss in a number of additional radii shall be used and the divisor in the equation shall be adjusted accordingly.

e. When the loss is limited to less than the full visual field, the degrees of loss in each included meridian shall be added to one-half of the sum of the two boundary meridians, boundary perimeters being the principal meridians on either side of the impaired field.

Ocular motility will be measured in all parts of the motor field either with or without correction as determined by the examiner to provide the most accurate determination.

a. All directions of gaze shall be tested from the extent of diplopia, with a test light on the perimeter at 300mm or on a tangent screen at a distance of one meter from the eye.

b. Reference is made to the AMA Guides for description of plotting requirements for the test results; (see Figure 1)

c. The percentage loss of ocular motility is the sum of the percentages of loss on motility due to diplopia in the meridian of maximum impairment. This percentage is assigned to the injured eye, or in the case of bilateral injury to the eye with the greatest impairment of CVA and VF. This is considered to be the eye with the greatest loss of CVA and the greatest loss of visual field and the percentage loss of ocular motility in the contralateral eye is considered to be 0, and for purposes of calculation, a value of 0 is deemed to be 1%.

IMPAIRMENT OF THE EYE

The visual impairment of one eye is the combination of the percentage losses of CVA, of VF, and of OM. To determine this, the visual loss is combined with the field loss for each eye. The loss in the eye that is greater is then combined with the loss of ocular motility.

Each of the following conditions present due to the injury causes an increase in the impairment rating of 2%.

a. Loss of color vision

b. Loss of adaptation to light and dark

c. Metamorphopsia

d. Uncorrected entropion or ectropion

e. Lagophthalmos

f. Epiphora

g. Muscle disturbances such as tics, not included under diplopia.

If glasses are required as a result of the injury, or if refractive error increases by at least one diopter of sphere, cylinder, or both, 5% is added to the impairment rating.

If a non-cosmetic contact lens is required as a result of the injury, 7% is added to the impairment rating.

WHOLE BODY IMPAIRMENT DUE TO VISION LOSS

The eye with the lower percentage impairment is considered the better eye and the one with the higher impairment is the poorer.

a. Multiply the percentage impairment of the better eye by 3

b. To this, add the percentage impairment of the poorer eye

c. Divide the sum of a. and b. by 4. This result is the percentage impairment of the visual system.

(Round fractions to the nearest whole number, rounding up and down from the midpoint.)

The percentage of impairment of the visual system is translated to the percentage of impairment of the whole body by using the following table.