Frame mirror and contact lens degree conversion
Conversion of contact lens degrees, conversion of contact lenses and optometry. The degree of optometry is the degree of the frame glasses, the degree of the frame glasses and the degree of the contact lens are different, and the distance between the posterior apex of the frame mirror and the cornea is about 12 mm. The degree of contact lens has a conversion formula, contact lens diopter = frame glasses diopter ÷ (1-0.012 × frame glasses diopter), 1 diopter is equivalent to 100 degrees as usual, myopia diopter is negative, hyperopia diopter is positive . 0.012 is the distance between the frame glasses and the highest point of the black eyeball, in meters.
Contact lens diopter = frame glasses diopter ÷ (1 + 0.012 × frame glasses diopter) There is a conversion formula for the frame mirror and the contact lens degree: Fo=Fs/(1-dFs) Fo-contact lens power Fs-frame mirror optometry d-frame mirror and corneal distance (0.012m) For example, if the frame mirror is -4.00D and the distance between the frame and the contact lens is 12mm, the degree of the contact lens can be converted to Fo=-4.00D/[1-0.012(-4.00)]=-3.82D, which can be pressed. -3.75D given. (Below -4.00D, the difference is small and can be ignored) If the frame mirror is between 4.00D and 5.00D, the degree of contact lens is: 0.25D for myopia and 0.25D for farsightedness; If the frame plus mirror degree is between 5.00D and 7.00D, the degree of contact lens is: 0.50D for myopia and 0.50D for hyperopia; If the frame plus mirror degree is 7.00D to 9.00D, the degree of contact lens is: myopia minus 0.75D, hyperopia plus 0.75D; If the frame mirror is 9.00D to 11.00D, the contact lens power is: 1.00D for myopia and 1.00D for farsightedness. If there is no corresponding degree after a certain degree of conversion, you can choose the nearest degree that is lower. For example, 800 degrees is 75 degrees and then 725 degrees. If there is no 725 degrees, you should choose 700 degrees, and so on.