Binocular Balance Test

The purpose of binocular balance examination is to make the stimulation of both eyes equal. Secondly, to make the subject's eyes achieve adjustment balance, visual acuity balance and visual acuity the same. The specific inspection methods include alternating covering method, prism separation method and polarization separation method.

1 Alternate Covering Method

1.1 Operation Steps

a. The best vision corrected by projection monocular.

b. Cover the left eye; Let the examinee look at the visual mark on the line with the best vision with his right eye and stay for 1 ~ 2 seconds; Then cover the right eye and let the subject look at the visual target with his left eye for 1 ~ 2 seconds; Repeat several times and compare the two eyes; If the visual acuity of both eyes is the same, judge the balance of both eyes; If the visual acuity of the two eyes is different, add + 0.25D in front of the clear eyes until the clarity of the two eyes is the same.

1.2 Comparison Of Advantages And Disadvantages

The advantage of alternating covering method is that it is convenient, fast, intuitive and easy for the examinee to understand. It is especially suitable for children, middle-aged and elderly people; Its disadvantage is that it is not compared under the condition of simultaneous vision of both eyes, which has limitations. The factors of unbalanced adjustment of both eyes will cause errors.

2 Prism Separation Method

2.1 Operation Steps

a. Based on the correction of both eyes, the built-in auxiliary lens is adjusted to 0. Binocular fog Plus + 0.75ds, pay attention to the simultaneous adjustment of both eyes.

b. Right eye 3△ BD, left eye 3△ Bu (Note: both eyes open at the same time).

c. Project a 0.6 ~ 0.7 single line of sight mark. First cover the left eye and check whether the right eye can recognize the sight mark, then cover the right eye and check the left eye to ensure that both eyes can recognize a 0.6 or 0.7 line of sight mark.

d. Ask the examinee to compare the clarity of the upper and lower lines. If there is any difference, adjust the spherical lens to make the visibility of the upper and lower lines the same (Note: compare when the upper and lower lines can be seen at the same time). If the upper and lower lines are difficult to be equally clear, ensure that the vision of the dominant eye is slightly better.

e. After the eyes are balanced, remove the prism and project the next line of visual targets to reduce the added spherical lens to the best vision.

2.2 Comparison Of Advantages And Disadvantages

The advantages of prism separation inspection are:

a. It is more comprehensive and standardized in the state of simultaneous vision of both eyes.

b. In the state of binocular fog, eliminating the error caused by adjustment factors can further ensure the balance of binocular vision and adjustment balance.

c. Compared with black-and-white visual standards, this method has high contrast, real image and more accurate results.

d. For patients with anisometropia in both eyes, a larger prism can be added in front of the eyes with low diopter (or a smaller prism can be added in front of the eyes with high diopter) to ensure that the transmittance of the lenses of both eyes is close. The disadvantage is that patients with vertical strabismus may be affected and limited.

3 Polarization Red And Green Inspection

Polarized red and green visual markers are four groups of black digital visual markers with red and green background. After polarization division, green 9-character and red 6-character visual markers can be seen in the right eye; Three characters on green background and five characters in red can be seen in the left eye. When both eyes look at the same time, four visual markers can be seen at the same time. The visual standard is equipped with red and green background color. Under the condition of simultaneous vision of both eyes, the monocular overcorrection or undercorrection can be judged according to the difference of visual standards of different colors.

3.1 operation steps

a. Binocular refraction was examined and corrected, and the polarizer was inserted into both eyes of the subject.

b. Project polarized red and green visual indicators, let the subjects compare whether the upper and lower red and green numbers (9 and 6 visual indicators) are the same clear, to judge whether the right eye is undercorrected or overcorrected, and let the subjects compare whether the left and right red and green numbers (3 and 5 visual indicators) are the same clear, to judge whether the left eye is undercorrected or overcorrected. If so, the visual acuity of both eyes is balanced.