Simple power conversion

optical frame glasses power

<-4.00D

-4.00D~-5.25D

-5.50D~-7.00D

-7.25D~-8.25D

≥-8.50D

contact lens power

No need conversion

Minus 0.25D

Minus 0.50D

Minus 0.75D

Pls refer to professional.

NoteThe above conversion table is only for reference. If special circumstances such as high power and astigmatism, etc., pls consult physician or optometrist while purchasing.  

Why sometimes the contact lens power differs from optical frame glasses power ?

The optical frame glass is placed in front of the eyes, a certain distance from the eyes ; while the contact lens is directly touched in the tear layer in front of the cornea, almost no distance from the eyes, and the vertex distance effect could almost be neglected. According to a certain principles of optics, nearsighted person's eyewear contact lenses power is slightly lower than optical frame glasses power, and within -4.00D, it has no need of conversion. If above -4.00D, it needs different levels of conversion. While fitting contact lens, optometrist will proceed with power conversion according to your results of optometry and fit you with appropriate lens.