Many friends don’t know much about eye chart conversion and table vision 10 and 50 conversion formulas. Today, the editor will share it with you. I hope it can help everyone. Let’s do it together. Let\’s see!
Contents of this article
- How to convert the size of the 3-meter visual acuity chart
- Table visual acuity 10 and 50 conversion formula
- The first three rows of the visual acuity chart are How many degrees
- How to convert a 5-meter eye chart when standing 3 meters away
- What is the number of meters on the eye chart
- How to convert between e eye chart and c eye chart
1. How to convert the size of the 3-meter visual mark on the eye chart
Generally 5 The meter-distance eye chart uses a light box. At a distance of 3 meters, the size of the visual target depends on the visual target projected by the phoropter. The size of the visual target is =3*tana
2. Table visual acuity 10 and 50 conversion formula
Eye chart grade=(actual vision-0.025)×10
Where, 0.025 is the difference between each level on the eye chart, For example, the first level on the eye chart is 1.0, the second level is 0.9, and so on.
For example, if a person\’s actual visual acuity is 0.4, then he can convert it to table visual acuity using the following formula:
3. What are the degrees in the first three lines of the eye chart?
They are 1000 degrees, 500 degrees and 300 degrees respectively. The eye chart corresponds to the degree of myopia. Generally, the data displayed on the eye chart is divided by 100. The first three lines of the visual acuity chart are 0.1, 0.2, and 0.3 respectively. According to this calculation, the myopia of 0.1 is 1000 degrees, the myopia of 0.2 is 500 degrees, and the myopia of 0.3 is 300 degrees. If you test your eyesight and find that the letters on the eye chart are divergent and not concentrated, you can preliminarily judge that the eyes haveAstigmatism
4. How to convert a 5-meter eye chart when standing 3 meters away
Example: The test result is 1.0. Actual result = 1.0×3÷5=0.6
When measuring visual acuity, the main thing is to check the uncorrected distance vision of one eye. The left and right eyes are tested separately. It is recommended that Use the order of first right and then left, gently cover one eye with your hand or a small plate, and look at the visual mark on the eye chart according to the examiner\’s requirements. The bottom line that the examinee can identify corresponds to the visual acuity. Corresponding naked eye visual acuity; for patients who have worn glasses or undergone laser refractive correction surgery, when undergoing a vision test, a corrected vision test should be performed at the same time, that is, the vision after wearing glasses or recovering from surgery. If the subject cannot see clearly the largest visual target \”E\” when standing at a distance of five meters, he or she needs to gradually walk into the eye chart until the largest visual target is recognized, and then calculate the corresponding visual acuity based on the formula.
5. What is the number of meters on the eye chart
This Usually on paper. The standard distance for this vision test is 2.5 meters or 5 meters. 2.5 meters and 5 meters correspond to different eye charts. The eye chart corresponding to 5 meters has a relatively larger visual mark, and the visual mark corresponding to 2.5 meters The visual targets will definitely be smaller accordingly, but their test results can be used as a reference for each other.
6. How to convert e vision chart and c vision chart
Nowadays, many people use eye charts to test their vision by themselves. Generally, the c-type eye charts and e-type eye charts are used. The visual acuity detected by different eye charts is the same, but the conversion relationship is slightly different. The c-type eye chart is widely used in the military. What is the conversion between c-shaped vision chart and E-shaped vision chart?
The 1.0 opening of the C-shaped eye chart for viewing from 5 meters away is 1.454 mm, 0.9 is 1.616 mm, 0.8 is 1.818 mm, and 0.7 is 2.078 mm . Similarly, the stroke width of the E and the gap between the strokes of the E-shaped eye chart are the same values. However, since the C-shaped vision chart has eight directions per symbol and only one notch, it is more difficult to see clearly (the E-shaped chart has only four directions and two notches).
In fact, it can be calculated. The visual angle of a person\’s standard 1.0 vision is one division, which is 1 of 1 degree./60. Therefore, the gap size of the 5-meter symbol is tan (1/60/1.0) * 5000, in millimeters. By replacing 1.0 with other visual acuity values, the gap width of the corresponding visual acuity symbol can be calculated. However, this is only for the decimal counting eye chart, not for the logarithmic eye chart with 5.0 as the standard visual acuity.
Assume that the value of the logarithmic visual acuity chart is x and the value of the decimal visual acuity chart is y, then x≈5+lgy. For example, 5.2≈5+lg1.5=5.176, 5.3≈5+lg2.0=5.301, 4.8≈5+lg0.6=4.778, 4.7≈5+lg0.5=4.699, 5.0=5+lg1.0. Both the C-shaped vision chart and the E-shaped vision chart have decimal scores (1.0 is standard vision). The logarithmic score (5.0 is the standard visual acuity) can also be used on the C-letter. The simple algorithm for the gap width of the decimal visual acuity chart is to use 1.0 as the standard, 1.4544 mm. 1.5 is 1.4544/1.5, and 0.7 is 1.4544/0.7=2.078.
That’s it for the introduction to eye chart conversion. Thank you for taking the time to read the content of this site. More about the table visual acuity 10 and 50 conversion formulas and eye charts. Don’t forget to look for conversion information on this site.
