eter. This last test is especially valuable in detection of scotoma.

[43 FR 45352, Oct. 2, 1978]

84.76a Computation of average concentric contraction of visual fields. The extent of contraction of visual field in each eye is determined by recording the extent of the remaining visual fields in each of the eight 45 degree principal meridians. The number of degrees lost is determined at each meridian by subtracting the remaining degrees from the normal visual fields given in table III. The degrees lost are then added together to determine total degrees lost. This is subtracted from 500. The difference represents the total

tory and findings reflect disease or injury of the extrinsic muscles of the eye, or of the motor nerves supplying these muscles. The measurement will be performed using a Goldmann Perimeter Chart as in Figure 2 below. The chart identifies four major quadrants, (upward, downward, and two lateral) plus a central field (20° or less). The examiner will chart the areas in which diplopia exists, and such plotted chart will be made a part of the examination report. Muscle function is considered normal (20/40) when diplopia does not exist within 40° in the lateral or downward quadrants, or within 30° in the upward quadrant. Impairment of muscle function is to be supported in each instance by record of actual appropriate pathology. Diplopia which is only occasional or correctable is not considered a disability.

$4.78 Computing aggravation.

In determining the effect of aggravation of visual disability, even though the visual impairment of only one eye is service connected, evaluate the vision of both eyes, before and after suffering the aggravation, and subtract the former evaluation from the latter except when the bilateral vision amounts to total disability. In the event of subsequent increase in the disability of either eye, due to intercurrent disease or injury not associated with the service, the condition of the eyes before suffering the subsequent increase will be taken as the basis of compensation subject to the provisions of §3.383(a) of this chapter.

[29 FR 6718, May 22, 1964, as amended at 43 FR 45354, Oct. 2, 1978]

$4.79 Loss of use of one eye, having only light perception.

Loss of use or blindness of one eye, having only light perception, will be held to exist when there is inability to recognize test letters at 1 foot (.30m.) and when further examination of the eyes reveals that perception of objects, hand movements or counting fingers cannot be accomplished at 3 feet (.91m.), lesser extents of visions, particularly perception of objects, hand movements, or counting fingers at distances less than 3 feet (.91 m.), being considered of negligible utility. With visual acuity 5/200 (1.5/60) or less or the visual field reduced to 5° concentric contraction, in either event in both eyes, the question of entitlement on account of regular aid and attendance will be determined on the facts in the individual case.

[43 FR 45354, Oct. 2, 1978]

$4.80 Rating of one eye.

§§ 4.81 4.82 [Reserved]

§4.83 Ratings at scheduled steps and distances.

In applying the ratings for impairment of visual acuity, a person not having the ability to read at any one of the scheduled steps or distances, but reading at the next scheduled step or distance, is to be rated as reading at this latter step or distance. That is, a person who can read at 20/100 (6/30) but who cannot at 20/70 (6/21), should be rated as seeing at 20/100 (6/30).

Combined ratings for disabilities of the same eye should not exceed the amount for total loss of vision of that eye unless there is an enucleation or a serious cosmetic defect added to the total loss of vision.

[41 FR 34257, Aug. 13, 1976, as amended at 43 FR 45354, Oct. 2, 1978]

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TIE

§4.83a Impairment of central visual an acuity.

The percentage evaluation will be found from table V by intersecting the horizontal row appropriate for the Snellen index for one eye and the verti-a cal column appropriate to the Snellen index of the other eye. For example, if one eye has a Snellen index of 5/200 (1.5/ 60) and the other eye has a Snellen index of 20/70 (6/21), the percentage evaluation is found in the third horizontal row from the bottom and the fourth vertical column from the left. The evaluation is 50 percent and the diagnostic code 6073.

[41 FR 11297, Mar. 18, 1976, as amended at 43 FR 45354, Oct. 2, 1978]

§4.84 Differences between distant and near visual acuity.