and Paolo Biondi2
(1)
Aesthetic and Maxillofacial Surgery, Padova, Italy
(2)
Maxillofacial Surgery, Forlì, Italy
Abstract
This chapter deals with references utilized for clinical facial analysis. I am convinced that judging the facial proportions and aesthetics utilizing internal and therefore “invisible” reference points, lines, and planes must be avoided. The inclination of the anterior cranial base, geometric center of the pituitary fossa, and other “invisible” references utilized in many cephalometric analyzes play a small role in the clinical decision-making process. So, more importance and emphasis is given to describing the points, lines, and regions of the external – visible – part of the face, together with the tissues that are under the skin and act as support structures.
This chapter deals with references utilized for clinical facial analysis. I am convinced that judging the facial proportions and aesthetics utilizing internal and therefore “invisible” reference points, lines, and planes must be avoided. The inclination of the anterior cranial base, geometric center of the pituitary fossa, and other “invisible” references utilized in many cephalometric analyzes play a small role in the clinical decision-making process. So, more importance and emphasis is given to describing the points, lines, and regions of the external – visible – part of the face, together with the tissues that are under the skin and act as support structures.
The introductory topic is dedicated to how any observer, not necessarily a professional, identifies and studies the facial points.
4.1 Eye Movements and Visual Perception
Studies of eye movements during visual perception provide information concerning the nature of internal representations of an object in the memory [3].
Eye movements are necessary for a physiological reason: detailed visual information can be obtained only through the fovea, the small central area of the retina that has the highest concentration of photoreceptors. Therefore, the eyes must move in order to provide information about objects that are being inspected. When the retinal field is mapped onto the visual cortex, there is a considerable geometric magnification of the signals coming from the fovea and a consequent reduction of signals coming from the periphery. In about 1 s, we are able to fix two or three regions of interest (ROIs), which are also called significant points of fixation; a rapid eye movement, requiring a very short time period, connects one ROI to the next [3, 4].
We know this from the work of Albert Yarbus, a Russian psychologist active in the 1950s and 1960s. He developed the first apparatus that could track exactly where people centered their eyes as they looked at a photograph [1, 5].
The moments of eye fixation, made while viewing simple drawings, indicate that these ROIs correspond to the angles of the figure. Other studies added the points of maximum curvature and the so-called unusual details and unpredictable contours to the previous significant points of fixation [2–4].
Knowing these spontaneously selected ROIs facilitates clinical facial analysis, as it:
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Helps in distinguishing what is “captured” during our visual perception from what is not.
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Provides some facial points that can be considered more important than others.
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Permits the exclusion of some facial points, utilized in the previous analysis, as they are not detected as ROIs with direct examination and clinical photographs.
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Permits the construction of an exclusive, personalized, and unique approach to each clinical case utilizing the ROIs.
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Avoids treating a singular case by matching it with “normal templates” or “normal values.”
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Helps the physician and the patient to discover and debate facial aesthetics with clinical photograph analysis. The ROIs are the same both for lay people and for the professional!
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Reduces the importance of abstract forms of analysis, such as cephalometric analysis, in planning the treatment and evaluating the results obtained.
4.2 From the Regions of Interest to the Facial Points of Interest
A human face is not a simple drawing like those utilized by Alfred Yarbus [5] for his study on eye movements, but, with different multiple views, it can be broken down into simple pictures. Chapter 3 is an example of that breakdown. Reviewing all the figures, we can note some points and lines that are evident in one view and completely hidden in another. This simple observation proves the limitation of the classic frontal and right profile views alone and the need for multiple views.
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