Basic knowledge to understand IOLs

Vision problems

This page is about basic refraction problems only. We will cover only

Myopia
Hypermetropia
Astigmatism

Rest of the eye deceases and conditions are not relevant to IOL performance understanding

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. Myopia

An eye condition, when the eyball size and optical power of the lenses are not matching each other in a way, that incoming light rays are focused before the retina. Eye is generally "too large".

To see clearly, patient needs "minus" glasses to adjust focus to its normal position.

2. Hyperopia

An eye condition, when the eyball size and optical power of the lenses are not matching each other in a way, that incoming light rays are focused after the retina. Eye is generally "too small".

To see clearly, patient needs "plus" glasses to adjust focus to its normal position.

3. Astigmatism

A condition when the cornea (rarely crystaline lens) is not of a perfect "spherical" shape. And this causes image distorsion as incoming light rays may focus in different planes before and/or after the retina. May be as a separate condition and be combined with myopia or hyperopia. Special "cylinder" lenses needed to correct that condition.

Aging eye vision problems

To ensure near to intermediate sharp vision, human eye have an accomodation mechanism. It is essential to understand how it works, in order to understand what is presbyopia and why we need reading glasses with age.

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