Mr Chan (M/46) came for a routine eye examination, complained that he cannot see near with his new glasses made few months ago, far vision is good. He is wearing Single Vision lenses (just one power).
His shortsighted power is -650 & -675 & astigmatism power of 075 same for both eyes, reading power is +100 or +125. Those with high power like Mr Chan, they need reading power slightly later & will be slightly lower as compared to those having good vision without glasses. For example, I’m almost 40, I have minimal power for my far vision, but i need +075 reading power already.
His power of existing glasses are optimised for far vision, but he has reading power now, so he needs to have another power optimised for his reading/near work. When we go past 40 years old, everyone will have “rabun dekat” or “lao hua” or “presbyopia”. This is because our natural lens inside our eye & eye muscles are not so flexible to help auto focus to see near already. They have been helping to do all this auto focus for the past 40 years. So, they slowly become less flexible and they require lenses (reading power) to support in order to see clearly & comfortably at near.
Now he has power for far vision and another power for near vision. Since his near power is still low, he can still manage to use just one power to enable him to see far & see far.. that is by lowering his far power. When we lower the power for far, the power that we have lowered.. as if.. is becoming your near power. He compromises sharpness abit from far vision and compromises sharpness abit from near vision so that he still can have one power in Single Vision lens to see far & near. We let him see himself his vision with far & near power as compared to just having one single power used for far & near. He is on sales line, he does not need to see sharply at far & he does not work in front of computer most of the time, so he is not expecting to want to see sharp vision for far & near.
It is all about knowing your visual needs, your expectation on your vision as well as your occupational visual requirement. Everyone is different. If you want sharp vision for far & near vision, or you are on computer work most of the time, most probably this compromised one power is not suitable for you, and you may need to consider see far & see near lenses, we call the Multifocal lens. Or if your reading power is low like Mr Chan, you can use Relax lens that acts like a transition class/”Kelas Peralihan” before you go to Form 1.. before you actually go into Multifocal lens.
If you find that your near vision has started become blurry already and you are in your 40s, come over for an eye examination. We will advise you accordingly 😉