**3. Ultraviolet absorbing intraocular lenses**

The crystalline lens absorbs ultraviolet radiation between 300 and 400 nm and protects the retina from photochemical damage [7]. This protective phenomenon is lost when the lens is removed during cataract surgery, but it can be restored by the implanting a UV-absorbing polymethylmethacrylate IOL. Implantation of a UV absorbing IOL results in cyanopsia or blue tinted vision. However it helps in preventing age related macular degeneration, improving contrast sensitivity and

**9**

**4. Future aspects**

*light-filtering IOLs [8, 9].*

**Figure 5.**

**5. Summary**

*Basic Science of Intraocular Lens Materials DOI: http://dx.doi.org/10.5772/intechopen.92573*

reducing glare in mesopic and photopic conditions. There are various UV-absorbing IOLs but they are not equally effective in absorbing UV radiation (**Figure 5**). To prevent the toxic effects of short wavelength light, IOL's have been developed that only block UV light but also reduce transmission of violet and blue wavelengths. The yellow pigment containing IOL's were first developed by Hoya in Japan followed by Menicon Co. Ltd. The first foldable IOL was developed by Alcon Laboratories.

*Comparison of transmission spectra of UV transmitting, UV blocking, violet light-filtering and blue* 

The incidence of endophthalmitis following cataract surgery has reduced significantly over the last few decades but it is still a nightmare for every eye surgeon. Post-operative instillation of topical antibiotics and antiinflammatory is the rule. However, recent studies show that delivery of these drugs intraocularly released from the IOL material may reduce the need for postoperative medication and thereby may further reduce the incidence of endophthalmitis. A combination of moxifloxacin and ketorolac is better than a combination of moxifloxacin with diclofenac [10]. Its effective against *Staph. aureus* and *Staph. epidermidis* for about 15 days. Further studies should be aimed at such modern dual drug delivery incorporated in the IOL.

Right from couching and rendering the patient aphakic, science has come a long way to manufacturing intraocular lens. The different materials have their own advantages and pitfalls owing to their chemical structure and inherent properties.

UV absorbing and dual drug delivery systems are the future.

*Basic Science of Intraocular Lens Materials DOI: http://dx.doi.org/10.5772/intechopen.92573*

**Figure 5.**

*Intraocular Lens*

the optic and haptics consisting of a foldable acrylic material. The table below gives

**Properties Single piece acrylic Three piece acrylic**

Visual acuity Same Same Refractive stability Same Same Centration Same Same SPCO formation More Less Anterior capsule opacification Less More Dysphotopsias Less More

Another subset of hydrophilic foldable acrylics is the Collamer lens. This Collamer material is a patented copolymer of hydrophilic acrylic and porcine collagen (<0.1%) hydroxyethyl methacrylate copolymer with a UV absorbing chromophore. In theory, the porcine collagen improves the biocompatibility of the lens when implanted in human eyes. It is a foldable phakic IOL consisting of a plate haptic with a central convex/concave optical zone and a forward vault to reduce the contact with the lens.

Size 5–7 mm 5.5–6.5 mm Foldable (minimum 1.8 mm)

Affinity to water hydrophobic hydrophobic Hydrophilic/hydrophobic Refractive index 1.49 1.41–1.46 1.39–1.42

Rigidity Rigid Flexible Foldable

**PMMA Silicone Acrylic**

The crystalline lens absorbs ultraviolet radiation between 300 and 400 nm and protects the retina from photochemical damage [7]. This protective phenomenon is lost when the lens is removed during cataract surgery, but it can be restored by the implanting a UV-absorbing polymethylmethacrylate IOL. Implantation of a UV absorbing IOL results in cyanopsia or blue tinted vision. However it helps in preventing age related macular degeneration, improving contrast sensitivity and

a comparison based on their different properties [5, 6]:

**8**

**2.4 Collamer**

**3. Ultraviolet absorbing intraocular lenses**

*Comparison of transmission spectra of UV transmitting, UV blocking, violet light-filtering and blue light-filtering IOLs [8, 9].*

reducing glare in mesopic and photopic conditions. There are various UV-absorbing IOLs but they are not equally effective in absorbing UV radiation (**Figure 5**). To prevent the toxic effects of short wavelength light, IOL's have been developed that only block UV light but also reduce transmission of violet and blue wavelengths. The yellow pigment containing IOL's were first developed by Hoya in Japan followed by Menicon Co. Ltd. The first foldable IOL was developed by Alcon Laboratories.

#### **4. Future aspects**

The incidence of endophthalmitis following cataract surgery has reduced significantly over the last few decades but it is still a nightmare for every eye surgeon. Post-operative instillation of topical antibiotics and antiinflammatory is the rule. However, recent studies show that delivery of these drugs intraocularly released from the IOL material may reduce the need for postoperative medication and thereby may further reduce the incidence of endophthalmitis. A combination of moxifloxacin and ketorolac is better than a combination of moxifloxacin with diclofenac [10]. Its effective against *Staph. aureus* and *Staph. epidermidis* for about 15 days. Further studies should be aimed at such modern dual drug delivery incorporated in the IOL.

#### **5. Summary**

Right from couching and rendering the patient aphakic, science has come a long way to manufacturing intraocular lens. The different materials have their own advantages and pitfalls owing to their chemical structure and inherent properties. UV absorbing and dual drug delivery systems are the future.

*Intraocular Lens*
