The Basic and Clinical Science Course comprises 13 volumes, incorporating fundamental ophthalmic knowledge, subspecialty areas, and special topics:

Readers who wish to explore specific topics in greater detail may consult the references cited within each chapter and listed in the Additional Materials and Resources section at the back of the book. These references are intended to be selective rather than exhaustive, chosen by the BCSC faculty as being important, current, and readily available to residents and practitioners.

xiv • Introduction to the BCSC

This edition of Section 13, Refractive Surgery, includes videos related to topics cov­ ered in the book. Selected by members of the BCSC faculty, the videos are available to readers of the print and electronic versions of Section 13 (www.aao.org/bcscvideo _section13). Mobile-device users can scan the QR code below (a QR-code reader may need to be installed on the device) to access the video content.

Each volume of the BCSC is designed as an independent study activity for ophthalmology residents and practitioners. The learning objectives for this volume are given on page 1. The text, illustrations, and references provide the information necessary to achieve the objectives; the study questions allow readers to test their understanding of the material and their mastery of the objectives. Physicians who wish to claim CME credit for this educational activity may do so by following the instructions given at the end of the book.*

The Basic and Clinical Science Course has expanded greatly over the years, with the ad­ dition of much new text, numerous illustrations, and video content. Recent editions have sought to place a greater emphasis on clinical applicability while maintaining a solid foun­ dation in basic science. As with any educational program, it reflects the experience of its authors. As its faculties change and medicine progresses, new viewpoints emerge on controversial subjects and techniques. Not all alternate approaches can be included in this series; as with any educational endeavor, the learner should seek additional sources, including Academy Preferred Practice Pattern Guidelines.

The BCSC faculty and staff continually strive to improve the educational usefulness of the course; you, the reader, can contribute to this ongoing process. If you have any sug­ gestions or questions about the series, please do not hesitate to contact the faculty or the editors.

The authors, editors, and reviewers hope that your study of the BCSC will be of last­ ing value and that each Section will serve as a practical resource for quality patient care.

* This activity meets the Self-Assessment CME requirements defined by the American Board of Oph­ thalmology (ABO). Please be advised that the ABO is not an accrediting body for purposes of any CME program. ABO does not sponsor this or any outside activity, and ABO does not endorse any particular CME activity. Complete information regarding the ABO Self-Assessment CME Maintenance of Certifi­ cation requirements is available at https://abop.org/maintain-certification/cme-self-assessment/.

Upon completion of BCSC Section 13, Refractive Surgery, the reader should be able to