For continuous display focometers, the top foci scale interval should not be greater than 0.25D, the scale interval in the axis direction should not be greater than 50, and can be interpolated to the nearest degree. The reading interval of the prism degree should not be greater than 1△ : For the digital display focometer, when the measuring range is -10D ~ +10D, the digital display increment of the diopter should not be greater than 0.125D. When the measurement range exceeds ±10D, the diopter digital display increment should not be greater than 0.25D. The numbers show values in two decimal places. The numeric display increment in the axis direction should be 10. The digital display increment of prism degree should not be greater than 0.25△.