Intraocular Lens (IOL) Design ,Material and Types

SEED Contact Lens

An Intraocular lens (IOL) is an artificial aid surgically implanted in the living eye to restore the sharpness of vision, frequently after removal of a cataract. A cataract is simply known as It is simply known as Opacification of the crystalline lens. In this topic, we are going to describe details about the history of Intraocular lenses, Types of IOL, Materials, and the manufacturing process.

History of IOL

  • Casaamata – (1795)- attempted an Intraocular implant
  • Harold Ridley (1949) — first successful human intraocular lens implant
  • During World War II, noticed intraocular foreign bodies of acrylic fragments from aeroplane canopies were tolerated.
  • Performed on November 29, 1949, at St. Thomas Hospital in London.
  • High incidence of complication – discontinued his original design
  • Pioneering work of Cornelius Binkhorst in Holland and E. Epstein in South Africa – interest in this modality rekindled.
  • Charles Kelman – Phacoemulsification – early 1970.
  • A major turning point of IOLs acceptance – 1974.
  • In 1976, Steven Shearing – first compressible posterior chamber lens


Pseudophakic vs. Aphakic vision

Pseudophakia is the condition where the Intraocular lens is placed after cataract sugery where as aphakia is the condition of No Intraocular lenses implanted in the eye.
Eyes having an Intraocular lens implanted are optically similar to the phakic condition (having natural crystalline lens).

Compared to the aphakic patient with high plus power lens spectacle correction, the pseudophakic patient has

  • Enlarged visual field,
  • Less magnification,
  • Better stereopsis,
  • Rapid visual  rehabilitation

Types of intraocular lens (IOL)

Here are the intraocular lens types

  • Anterior chamber IOL,
  • Iris-fixated IOLs,
  • Posterior chamber IOLs,
  • Sulcus-fixated IOLs.


Ideal implant material


  • High optical quality
  • A high index of refraction
  • Lightweight
  • Durability
  • Ease of  manufacture
  • Lack of inflammatory reaction
  • Lack of antigenicity
  • Lack of carcinogenicity
  • Ease of sterilization

OPTIC Materials of Intraocular Lens (IOL)

PMMA  (polymethyl methacrylate)

  • Can be used to create a single vision or multi-focal lenses
  • Surface modification – reduce the immediate postoperative inflammation in high-risk eyes.
  • Graft Hydrogel to its surface
  • Heparin coating
  • Fluorocarbon or Teflon coating of the lens.
  • Surface passivation

The drawback of PMMA IOL

  • PMMA is not totally inert
  • Hard, rigid material
  • Monomer – toxic to the eye
  • Nd: YAG laser has the potential to damage  PMMA optic.
  • Hydrophobic – corneal endothelial cells adhere to their surface.
  • Larger incision required

IOL made with PMMA material

New Materials

Avoiding problems associated with rigid lenses – use softer polymeric materials for lenses.

  • Silicone
  • Hydrogels
  • Foldable Acrylics


Foldable IOL implant pros and cons


Cellular response

  • Less than PMMA lenses.

Optical quality

  • Silicone IOL no finishing or polishing is required.
  • Have transmissions of >90% in the 400-800nm range.
  • Excellent surface properties that reduce reflection and glare.

Bio-stability and chemical purity

  • Resistant to hydrolytic and oxidative degradation.
  • Harmful chemicals fully extracted during the making.
  • Low adhesion – low pigmentary and inflammatory deposits.

Sterilization and laser effects

  • Autoclaved safely avoiding harmful gases or chemicals.
  • Exposure of silicone IOL to LASER doesn’t release any harmful chemicals.



Biocompatibility of materials other than silicones:

  • Silicone has been proved to be biocompatible. Mechanical strength:

Tensile strength considerably lower than that of PMMA 

  • care must be taken while handling soft IOL.
optic and haptic of intraocular lens
IOL Parts

Loop and Haptic materials

Broadly divided into

  • One-piece with PMMA haptic or soft biomaterials

Multi-piece consisting of an optic supported by one or more loops (haptics).

  • Polymide
  • Prolene
  • Mersilene

Quality Control of IOL

  • Must be within 0.25D of stated power
  • Proper shape and configuration within 0.25mm
  • Uniform, smooth surfaces, and edges
  • Chemically pure without any residual monomer, ethylene oxide, or contaminants
  • Clean of surface debris; and be sterile.

Sterilization For PMMA: Ethylene oxide most commonly uses, Alternative method sterilization using sodium hydroxide. And for acrylic IOL Autoclave is done.

Design characteristics, optic size

  • IOL optic size ranges from 4.5-7.5mm
  • Optic size of 6.5-7.0mm is popular among surgeons performing planned ECCE.
  • Lenses with the round optic of 5.5-6.0mm are currently favoured by many phacoemulsification surgeons.
  • Some surgeons- prefer oval lens  5mm x 6mm optics.

Large optic size IOL

  • Less likelihood of decentration.
  • Less optical aberration.
  • Reduced likelihood – pupillary capture.

Small optic IOL

  • Most popular in phacoemulsification and continuous tear anterior capsulotomy.
  • Minimal displacement in a bag- favoured by most phaco surgeons.
  • Potential for optical aberration from lens edges.

Shape of IOL

The biconvex lens seems to be the soundest design.

– Simulates natural lens and provides good optical quality.
– Capable of retarding opacification from Elschnig pearls.

IOL Lens Design

  • AcrySof® Natural IOL
  • Piggyback IOL
  • Phakic IOL
Iris Hook IOL
Iris Hook IOL

Multifocal IOL design

  • Toric IOL
  • Accommodation IOL
  • Smart IOL

multifocal IOL

Intraocular Lens Production in Nepal

How intraocular lenses are made?

Here is the detailed video related to the intraocular lens manufacturing process of Fred Hollows Laboratory, Kathmandu, Nepal

Intraocular lens manufacturers in Nepal

The Fred Hollows Intraocular Lens Laboratory (FH IOL LAB), Tilganga Institute of Ophthalmology manufactures high-quality low-cost Intra Ocular Lenses of both categories Rigid IOL from PMMA and Foldable IOL.



IOL Manufactured by FH IOL laboratory (Tilganga institute of ophthalmology) Nepal are as follows:

Foldable IOL:

 “Flex” Sterile Foldable Acrylic Intraocular lens

  • Material: Poly-HEMA Acrylic
  • Refractive index=1.461
  • Design: Biconvex Optic ‘C’ loop
Design of "Flex" Sterile Foldable Acrylic Intraocular lens made in Nepal by FH IOL laboratory.
Design of “Flex” Sterile Foldable Acrylic Intraocular lens made in Nepal by FH IOL laboratory.

“Tetra” Sterile Foldable Acrylic Intraocular lens

"Tetra" Sterile Foldable Acrylic Intraocular lens
“Tetra” Sterile Foldable Acrylic Intraocular lens

Tecsoft “Micro” Sterile Foldable Acrylic Intraocular lens

Tecsoft ” Slick ” Sterile Foldable Acrylic Intraocular lens


PMMA and Other Products of FH IOL Laboratory:

  • Kelmann Type AC “PMMA” IOLS
  • Modified C PMMA IOLS
  • Sterile PMMA capsular tension ring
  • Hydro-Glide Mini
  • Hydro-Glide
  • TEC-JECT Injection System
  • Hydro-Shooter

How to buy Fred Hollows Intraocular Lens

If you want to purchase Intraocular Lens manufactured by FH IOL, Tilganga Institute of Ophthalmology, you can contact on following contact details:

The Fred Hollows Intraocular lens laboratory
Tilganga Institute of Ophthalmology
Bagmati Bridge, Gaushala
GPO Box 561, Kathmandu, Nepal
Telephone: +977 1 4493775
Fax: +977 1 4474937
Email: [email protected]



  • Cataract surgery and complications- Norman F Jaffe (2nd Edition)
  • Duane’s ophthalmology- CD ROM -2005
  • Albert Jakobeic CD ROM (5th Edition)
  • AAO Series- Lens And Cataract (2004-2005)
  • Ophthalmology Monographs- Intraocular Lenses(1993)
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