**1.6 Prevention of PCO**

The properties of the IOL such as affinity for water, adhesiveness and presence of square edge contribute in prevention of opacification of posterior capsule after cataract surgery.

## **1.7 IOL design**

*Intraocular Lens*

7.IOL design

**Figure 1.**

**1.1 Affinity for water**

*surface (b) contact angle is <900*

**1.2 Refractive index**

**1.3 Size**

**1.4 Adhesiveness**

**1.5 Glistening phenomenon**

in toric IOLs.

are inversely proportional.

5.Presence or absence of glistening phenomenon

6.Prevention of posterior capsular opacification (PCO)

*Contact angles of water on hydrophobic and hydrophilic surfaces. (a) Contact angle is >900*

 *on hydrophilic surface.*

is, the more hydrophilic the material is defined and vice versa.

IOL materials are defined hydrophobic or hydrophilic according to the angle a drop of water makes with respect to the material surface. The more acute this angle

 *on hydrophobic* 

Refractive index of a material refers to ratio of velocity of light in vacuum to velocity of light in that medium. It is a measure of bending of light rays when they travel through a particular medium. The refractive index and thickness of the IOL

The optic diameter and the length of the haptics are taken into consideration when the size of the IOL is to be measured. The size of the incision, the type of injector and methods of introducing the IOL are all based on the size of the IOL.

Adhesiveness is a property by which the IOL fuses with anterior and posterior capsule and hence reduces the risk of decentration. This property becomes essential

Penetration by aqueous humor has been noted to cause small vacuoles within the

lens optic. This phenomenon is called 'glistening phenomenon'.

**4**

The structure and design of IOL contributes to its ability to remain centered in the capsular bag. The shape and length of haptics and the optical diameter are taken into consideration in designing an intraocular lens.
