<p>1. Gradient method measurement of AC\/A</p> <p>2. Measure the pupil distance and select a trial frame that is consistent with the pupil distance;</p> <p>3. The refractive error of the subject's eyes is completely corrected;</p> <p>4. Insert +100-degree spherical lenses in front of both eyes at the same time;</p> <p>5. Insert a Maddox rod lens in front of the right eye to keep the Maddox rod grid stripes horizontal;</p> <p>6. Place the proximal Torrington plate 40cm in front of the eyes, turn on the power, and keep the light source and the line of sight horizontal;</p> <p>7. Ask the subject about the positional relationship between the light source and the vertical line he sees, and record it;</p> <p>8. Remove the +100-degree spherical lens, and then insert a -100-degree spherical lens in front of both eyes at the same time;</p> <p>9. Ask the subject about the positional relationship between the light source and the vertical line he sees, and record it;</p> <p>10. Subtract the first recorded value from the second recorded value, and then divide it by 2, which is the AC\/A value.</p> <p>Power Supply: 2 x AA batteries(Not included batteries)</p> <p>Colour:White</p> <p>Material:ABS</p> <p>Package Contents:</p> <p>1 * Squint Vision Detection Tool</p> <p>1 * Stand</p> <p>Only the above package content, other products are not included.</p> <p>Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +\/- 1-3cm.</p>