Jorge L. Alió - Multifocal Intraocular Lenses: The Art and the Practice

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In our modern world, now on the first quarter of the twenty-first century, medicine faces, more than ever before, the challenge of not only fighting diseases and saving lives but also improving quality of life. While life expectancy rises, patients activities remain at the same level that they were used to being young and hence their visual demands keep being high. While in previous decades older people tended to lessen their activity, nowadays older people do not reduce daily activities as driving, sport activities, and various hobbies that require good visual acuity to different distances and are more convenient if multifocality exists.

This evolution derived among other things new techniques and new approaches of cataract surgery. The evolution of cataract surgery and IOL implantation during the last decade has been, not surprisingly, focused on improving the quality of vision and the quality of life of our patients.

Near vision and intermediate vision have been identified as one of the reasons by which quality of life is really acknowledged by our patients. Another trend in recent years is the tendency to operate younger patients than before with better visual acuities, even with mild cataracts, which means that patients are less tolerant to visual disabilities, and moreover the advances in refractive surgery have educated them in their request for spectacle independence. While usually we succeed in achieving good far vision without spectacles or contact lenses, optimal multifocality for far, intermediate, and near vision is still a challenge to be met.

Since multifocal lenses, by definition, divide light into different foci, using multifocal intraocular lenses causes a dispersion of the energy of light entering into the eye and, consequently, distributing the light in different foci. This causes a change in distribution of light and images at the level of the visual function at the level of the retina. This is the reason why neuroadaptation, which means the capability of the brain to adapt to changes, is necessary to adjust neurophysiology to the changes that are induced in the quality of the retinal image by dispersion of light. Moreover, the overlapping of different foci is neither physiological nor normal in the human or animal evolution. To the best of our knowledge, no visual system is multifocal in nature and it has not existed in the human being throughout evolution. For this reason, neuroprocessing is the main challenge of multifocal intraocular lenses. The new technologies emerging in recent years have aimed at smoothing the changes in visual perception and to make a much more physiological division of light, but even in these conditions, their effectivity has to be demonstrated and confirmed by an improvement in the subjective quality of vision of the patient.

About four years ago we published the first edition of this book which was welcomed by many ophthalmologists around the world. In recent years, a tremendous advance in the field of multifocal intraocular has been made. In this second edition, we bring the updated information on multifocal intraocular lenses techniques and about lenses available in the market today as well as our personal experience on the subject. The main aims of this book are how the practical ophthalmologist and ophthalmic surgeon can select an adequate multifocal intraocular lens, how to differentiate them among the different technologies, how to identify the best on the market, and how to use evidence in favor of the selection of the best for the benefit of the patients.

We hope that the reader will find this book useful for the purpose for which it was created, independent opinion, information, and credibility, and also unbiased information on the subject of multifocal intraocular lenses, which is constantly progressing and takes more and more part in our daily clinical practice. If we achieve this goal, the time and work dedicated to this book will be worthy.