8.3.4 Intraocular Lenses to Restore and Preserve Vision Following Cataract Surgery

8.3.4Intraocular Lenses to Restore and Preserve Vision Following Cataract Surgery

Robert J. Cionni and David Hair

Core Messages

ßOur ability to restore the vision lost due to cataracts has improved tremendously over the

last few decades.

ßMore focus on maintaining the vision is essential, especially for patients with macular degen-

eration.

ßBlue light has been shown to be potentially damaging to the retina.

ßThe normal human crystalline lens filters out a significant amount of high frequency blue

wavelength light. Removal of this lens and placing a colorless UV blocking IOL leaves the retina exposed to higher levels of blue light.

ßIOLs are now available that can filter out blue light similar to the normal human lens.

ßBlue light filtering IOLs have been shown to have no negative effect on visual acuity, contrast

sensitivity, color perception, or night vision.

8.3.4.1 Introduction

Advancing surgical and intraocular lens technologies now offer our patients the opportunity of excellent vision following surgery. Newer multifocal and accommodating IOLs now offer the possibility of restoring vision to the pre-presbyopia state and thus, reduce spectacle dependency for both distance and near vision [1–4], Unfortunately, many of our cataract patients also suffer from, or may later develop, age-related macular degeneration. Despite our successes at

R. J. Cionni ( )

The Eye Institute of Utah, Salt Lake City, UT 84107, USA e-mail: rcionni@theeyeinstitute.com

restoring vision for our cataract patients, we have not gained significant ground in preserving the vision for those patients with macular degenerative disease. Over the last few decades, more literature has surfaced suggesting that blue light may be one of the factors related to the progression of age-related macular degeneration [5]. Additionally, the role of blue light and its association with the increased risk of choroidal melanoma is becoming more apparent [6].

In addition to ultraviolet light, it is well known that the normal human crystalline lens filters much of the high frequency blue wavelength. Thus, when we remove the crystalline lens, clear or cataractous, and replace it with a clear, nonfiltering IOL, we may be decreasing the eye’s natural ability to protect against worsening ARMD or malignant melanoma. In this chapter, we will investigate the rationale for implanting blue light filtering IOLs. We will also evaluate the differences in the various blue light filtering IOLs available in the market today.

8.3.4.2 Why Filter Blue Light?

It is well known that pseudophakic eyes are more susceptible to retinal damage from near ultraviolet light sources [7, 8]. Pollack et al., followed 47 patients with bilateral early ARMD after they underwent extracapsular cataract extraction and implantation of an UV-blocking IOL in one eye, with the fellow eye as a phakic control [9]. Neovascular ARMD developed in nine of the pseudophakic eyes vs. two of the control eyes, which the authors suggested, might be due to the loss of the “yellow barrier” provided by the natural crystalline lens.

Data from the Age-Related Eye Disease Study (AREDS) suggest a heightened risk of central geographic retinal atrophy in pseudophakic eyes [10]. The retina appears to be susceptible to chronic repetitive exposure to low-radiance light as well as brief exposure to higher-radiance light [11–14]. Chronic, lowlevel exposure (Class 1) injury occurs at the level of the photoreceptors and is caused by the absorption of photons by certain visual pigments with subsequent destabilization of the photoreceptor cell membranes. Sparrow and colleagues have demonstrated that a component of lipofuscin, known as A2E, is integral in blue light-induced retinal pigment epithelium (RPE) damage [15–17]. Although the retina has inherent