**Abstract**

This chapter will explain the materials used in making intraocular lenses. Rigid IOL's made of PMMA have now given way to foldable silicone and acrylic lenses. This chapter will also throw light on the indications and contraindications for using each of the IOL's. The composition of each of the lenses, their water content, mechanical properties and their special ultraviolet absorbing features will be discussed in detail. The mechanism by which hydrophilic lenses are inserted through small incisions during cataract surgery will need a special mention. The problems with use of different types of intraocular lenses will also be dealt with.

**Keywords:** intraocular lens, material, PMMA, acrylic, silicone

### **1. Introduction**

Cataract surgery is being carried out for over more than 3000 years. What began as simply dislodging the cataractous lens posteriorly into the vitreous, also known as couching, got the ball rolling. And now we have advanced surgical techniques with minimal incision size and excellent visual prognosis due to the recent advances in intraocular lenses (IOL) [1].

In November, 1949, Dr. Harold Ridley implanted the first intraocular lens after extracapsular cataract extraction (ECCE) in a 45 year old female at St. Thomas Hospital, London [2]. This IOL was made of a material called Polymethylmethacrylate (PMMA).

After a lot of clinical trials and initial disapproval, it wasn't until 1970, that IOL implantation became a well accepted procedure. And hence began a revolution in the field of cataract management. Over the past 5 decades there have been monumental breakthroughs and various IOLs of finest elements are now routinely being implanted (**Figure 1**).

An intraocular lens can be described on the basis of certain properties possessed by the material it is made up of. These properties include the following:


**Figure 1.**

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

5.Presence or absence of glistening phenomenon

6.Prevention of posterior capsular opacification (PCO)

7.IOL design

### **1.1 Affinity for water**

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