Contact lens Questions

Question

how do you get your eyes' base curve size ?

is it true that we should wear contact lens with a lower power than our original minus ?

ex : I have 550 minus, and they told me to wear 500 contact lens

Answer 1

In higher eye numbers (>4.00), "vertex distance" is a parameter that should be considered in the final prescription. It's the distance of the corrective lens from the front surface of the eye [cornea]. When examining, the doctor places the trial lenses at about 12 mm from your eyes. But contact lenses lie directly on your cornea at a virtual "zero" distance. The effective power of a lens changes as it approaches the eye. As a rule of thumb: as the lens moves toward the eye, the prescription should move toward "plus". The higher your eye number, the difference rises between your glasses and your contact prescription.

The base curve of the contacts is determined by your doctor after measurement of the convexity of your front corneal surface in different meridians by keratometry or probably topography. This is more important in prescribing hard contacts, which requires an additional  time consuming  "fitting" of many trial lenses, to find the best base curve for your eye.

Answer 2

U can get ur bc from the eye doc. It is normal to down the degree when u r wearing lenses as compared to spects