Among all the possible subjects for the presentation of a Monograph, one of the obligations of the extended group - that during a biennium has the responsibility to guide the Portuguese Society of Ophthalmology, Presbyopia was elected. A cross cutting issue for the ophthalmological community, which has had very important recent developments, in its approach, in its better understanding, and in its therapeutics.

Gone are the times in which Aristotle alluded to the subject, in which in thirteenth century Florence assumed the manufacture of corrective lenses, and in which in the seventeenth century the best understanding of accommodation is outlined.

And at the end of this long period, doubts and different theories still try to explain the most intimate mechanisms of this process of senescence of the visual system. If a few years ago, its clinical resolution was relatively simple - and still is in most cases, a society that wants a more effective response to what is inevitable, the passing of years, obliges us to find new solutions, some of great creativity and sophistication.

Our good personal and scientific relationship with the Ophthalmological Societies of Brazil and Spain has led us to ask for their collaboration in this project, thus enriching this Monograph that will be a joint work of our Societies. To all those who have agreed to contribute to this work, often sacrificing other obligations, the SPO Central Commission and the Portuguese Ophthalmology are very grateful.

To Mrs. Prof. Filomena Ribeiro, who as Coordinator of Implant-Refractive Surgery of Portugal took care of the coordination of this Monograph with great dedication and commitment, our thanks.

A very special word for the Théa Laboratories, that for many years make possible with great professionalism, the publication of the SPO monographs.