We believe this handbook's new edition will inform clinicians and technicians on the recent advances in OCT imaging.

In this second edition of the Practical Handbook of OCT, we offer a step-by-step guide for interpreting images and data acquired by OCT, “En face” OCT and OCT Angiography. In these pages, as in all the handbooks, we have written on Ocular Imaging, we have applied a logical method for interpreting ophthalmic images. The first phase is analytic: it subdivides each image into its smallest parts. The second phase of this method combines these elementary components to synthesize the data, allowing an accurate diagnosis and treatment decision.

We trust this handbook will help Ophthalmologists, Residents, Ophthalmic Technicians and Optometrists understand and appreciate the new possibilities offered by latest OCT devices.

OCT technology presents us today with an exponential increase of the quantity of data we have to classify, sift, assess, count, and preserve. Most operators in everyday work use only a small part of OCT possibilities. At present, OCT devices technical evolution begins to exceed the interpretation and analytic abilities of the specialists to which they are entrusted with.

Assessment and interpretation activity involves both a technical dimension and an intellectual aspect. We have written the present handbook with these facts in mind. We tried to teach a logical method of analysis and interpretation of the clinical images to help and guide clinicians in assessing, classifying, and selecting information.

We would like to thank Donata Piccioli, the artist, who illustrated all our scientific works for her beautiful drawings and the collaboration in making wonderful artwork out of our rudimentary schematic outlines.

This manual applies the classical Cartesian method of analysis followed by synthesis to OCT to teach how to disentangle the complex web of information. The intended purpose is to improve and standardize decisions made in interpretation of OCT images. Its basis is a logic-based diagnosis decision support system. This methodology uses a logical progression as seen in the flow charts.

As soon as we got and first used OCTs, we tried first to understand how to interpret logically the images without trying shortcut the necessary steps. This approach has been tried and applied in numerous courses, conferences, and seminars.

Analytic application is not easy and approach self-evident. OCT logical analysis must subdivide images into their basic elements, morphology, structure, architecture, framework, and stratification. Each scan will be assessed according to its morphology, high or low reflectivity. Structure, texture, and morphology are tightly interwoven with reflectivity variations and abnormal formations (cavities, deposits, fluid accumulations, exudates, hemorrhages, etc.). Image deconstruction is not easy. The basic elements are sometimes very difficult to highlight and separate. In fact, the images obtained with OCT are so complex and intricate that they cannot be simply considered a puzzle solved only by sorting. Retinal diseases can modify architecture and morphology beyond recognition and interpretation. Automatic or manual segmentation attempts may be impossible.

If the basic principles of analysis are respected, reconstruction and synthesis are easier; and it will be possible to reach the correct diagnosis.

Our figures were obtained mainly by Optovue OCT, but also by Zeiss Cirrus, OPKO/OTI, and Topcon devices. We used most of the time grayscale rather than conventional pseudo-colors to make out details that could be easy to miss.