How to choose the prescription of contact lenses
How to choose the prescription of contact lenses
Contact lenses are convenient and fast, and they are natural, becoming a fashion for many people and a tool for correcting myopia, but for friends who are in contact with contact lenses for the first time, they usually bring glasses with prescription, and they often don't know how to choose the prescription when they suddenly choose contact lenses. How to choose the prescription of contact lenses? Usually the power of our refraction is the power of glasses, the distance between the back apex of Asian glasses and the cornea is about 12mm, and the contact lens is directly worn on the eyeball, if the power of the glasses is also used, it will cause overcorrection, that is, the power is too high, you may be dizzy or uncomfortable to see, the eyes are easy to get tired, and myopia is easy to deepen after a long time. So how should we choose the prescription of our contact lenses? Generally speaking, if your glasses are corrected to 0.8 or 0.9 and your prescription is not high, you can use them directly; However, if your glasses have fully corrected your vision, and your prescription is not too high, you can directly lower it by 25 degrees; If you want to convert the power accurately, you can use the following method: The conversion formula between the power of the lens and the contact lens: Fo=Fs/(1- dFs). Fo - contact lens power, Fs - refraction power of the frame lens, d - the distance between the frame lens and the cornea (0.012m), for example: the power of the frame lens is -4.00D, the distance between the frame and the eyeball is 12 mm, then the power of the contact lens can be converted to Fo = 4.00D/[1-0.012(-4.00)] = -3.82D, which can be matched according to -3.75D. Many people see this formula and find that it is a bit complicated and have a headache, don't worry about this, now there are many converted prescriptions on the Internet that can be used directly, the following is the table of conversion of prescription for glasses to prescription for contact lenses, you can refer to it. push