Basic knowledge to understand IOLs
Human vision basic
A young healthy human eye is designed to
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Provide a sharp vision at infinity.
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Adjust eye focus on objects in range of about 30-100cm from the eye to provide sharp vision at this range at any given distance.
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Adapt to amount of light around by adjusting the pupil size and using different types of photosensitive cells on a retina - rods and cons.
Eye anatomy
You shall know basic eye anatomy in order to understand how IOL implantation may impact your vision quality, and why IOL optics type is important in order to give you freedom of glasses.
The core principle is: the eye is a system of 2 lenses - cornea and crystalen lens.
These lenses shall have an optical power, ideally suited eyball length in order to focus incoming light rays on the retina sharply.
1. Far vision
By nature we shall see clearly to the far, or better to say to infinity. The eye status, when human can see sharply at infinity called emmetropia, which means that eye refraction is normal and incoming light rays are focused ideally sharply on a retina.
2. Vision at near
Normally you hear about near vision, but generally we are talking about near and intermediate vision, which covers a range of distances from about 30 to 100 cm from the human eye. That vision is possible as we do have eye acccomodation, described on the next page.
3. Light adoptation
Human eye is designed to adapt to different lightning conditions from sunny day to dark night. For that purpose we do have pupil which regulates amount of incoming light, and 2 types of retinal cells to react better in bright and dim light conditions.