Key points

Introduction

Human beings use skin features including color uniformity, color distribution, and texture to infer the physiologic health status of others. For example, visual responses to facial-image sets standardized for shape and surface features were recorded with eye-tracking methods. Those images with more uniform skin coloration drew more attention and were perceived to be younger than those with greater color variability. The distribution of skin color on the face has also been associated with the perception of overall health. These factors can reduce the perceived age by as many as 20 years. This homogeneity in skin color is also related to perceived age and health in men. Color itself influences the perception of health. In one study, observers were asked to adjust the redness of high-resolution facial images to achieve their own perceived “healthy appearance.” All of them increased the red coloration, regardless of their inherent pigmentation, but subjects with dark skin increased the red component of dark-skin photos more than for those with lighter skin. The perception of age may vary, however, depending on the person’s ethnicity. High-resolution photographs of the cheek region from Japanese women aged 13 to 80 years were viewed by 10 Japanese judges. Using skin lightness (L) and b* color (blue-yellow), those with darker and more yellow skin were perceived to be older.

Facial skin texture, such as wrinkling caused by photodamage, also influences the rating of attractiveness and beauty. Periorbital features including the presence of festoons and crow’s-feet in addition to perioral features such as the presence of wrinkles and fullness of the lips also influence the perception of age. However, the age of individuals may affect which facial regions are aesthetically important both to themselves and when evaluating others. Sezgin and colleagues grouped female cosmetic-surgery patients by age and asked which facial characteristics they evaluated in themselves or others. The older subjects examined the periorbita and jawline, whereas younger patients concentrated on the nose and skin.

General health questionnaires such as the GHQ 30 have been used to determine the impact of facial skin conditions (eg, acne) as well as the effects of treatment in individuals. Patients undergoing facial rejuvenation procedures reported significant, positive effects on quality-of-life attributes when evaluated with the Derriford Appearance Scale. The greatest improvements were in these factors (in descending order): general self-consciousness of appearance, social self-consciousness of appearance, self-consciousness of sexual and bodily appearance, negative self-concept, self-consciousness of facial appearance, and physical distress and dysfunction.

With the population aging in developed countries, attributable in part to improvements in health care and technology, surgical and nonsurgical therapies including cosmeceuticals and cosmetics are highly sought after to reduce one’s perceived age. Kosmadaki and Gilchrest found that increased longevity is accompanied by significant interest in the quality of life and appearance. The demand in the United States, driven largely by the baby-boomer generation, has prompted the development of an armamentarium of methods for managing and optimizing facial skin color, texture, and shape. This article and the one that follows address 2 contemporary and relevant topics concerning photodamaged facial skin, because of its increasing prevalence.

This article addresses the strategies and available methods for measuring treatment outcomes, perhaps defined by the consumer/patient as “decrease in perceived age.” The second article presents studies on facial rejuvenation that have used these quantitative methods to modify perceived age.

Introduction

Human beings use skin features including color uniformity, color distribution, and texture to infer the physiologic health status of others. For example, visual responses to facial-image sets standardized for shape and surface features were recorded with eye-tracking methods. Those images with more uniform skin coloration drew more attention and were perceived to be younger than those with greater color variability. The distribution of skin color on the face has also been associated with the perception of overall health. These factors can reduce the perceived age by as many as 20 years. This homogeneity in skin color is also related to perceived age and health in men. Color itself influences the perception of health. In one study, observers were asked to adjust the redness of high-resolution facial images to achieve their own perceived “healthy appearance.” All of them increased the red coloration, regardless of their inherent pigmentation, but subjects with dark skin increased the red component of dark-skin photos more than for those with lighter skin. The perception of age may vary, however, depending on the person’s ethnicity. High-resolution photographs of the cheek region from Japanese women aged 13 to 80 years were viewed by 10 Japanese judges. Using skin lightness (L) and b* color (blue-yellow), those with darker and more yellow skin were perceived to be older.

Facial skin texture, such as wrinkling caused by photodamage, also influences the rating of attractiveness and beauty. Periorbital features including the presence of festoons and crow’s-feet in addition to perioral features such as the presence of wrinkles and fullness of the lips also influence the perception of age. However, the age of individuals may affect which facial regions are aesthetically important both to themselves and when evaluating others. Sezgin and colleagues grouped female cosmetic-surgery patients by age and asked which facial characteristics they evaluated in themselves or others. The older subjects examined the periorbita and jawline, whereas younger patients concentrated on the nose and skin.

General health questionnaires such as the GHQ 30 have been used to determine the impact of facial skin conditions (eg, acne) as well as the effects of treatment in individuals. Patients undergoing facial rejuvenation procedures reported significant, positive effects on quality-of-life attributes when evaluated with the Derriford Appearance Scale. The greatest improvements were in these factors (in descending order): general self-consciousness of appearance, social self-consciousness of appearance, self-consciousness of sexual and bodily appearance, negative self-concept, self-consciousness of facial appearance, and physical distress and dysfunction.

With the population aging in developed countries, attributable in part to improvements in health care and technology, surgical and nonsurgical therapies including cosmeceuticals and cosmetics are highly sought after to reduce one’s perceived age. Kosmadaki and Gilchrest found that increased longevity is accompanied by significant interest in the quality of life and appearance. The demand in the United States, driven largely by the baby-boomer generation, has prompted the development of an armamentarium of methods for managing and optimizing facial skin color, texture, and shape. This article and the one that follows address 2 contemporary and relevant topics concerning photodamaged facial skin, because of its increasing prevalence.

This article addresses the strategies and available methods for measuring treatment outcomes, perhaps defined by the consumer/patient as “decrease in perceived age.” The second article presents studies on facial rejuvenation that have used these quantitative methods to modify perceived age.

The nature of photodamaged skin

Solar exposure at suberythemal levels, or below the exposure required to produce visible skin erythema, is sufficient to cause photodamage. Histologically, photodamaged skin has the following features: increased epidermal thickness, a flattened dermal-epidermal junction, chronic inflammation, thickened walls in the microvascular circulation, lengthened and collapsed fibroblasts, reduced levels of types I and III collagen, increased elastin, and poor organization of the collagen fibrils. These changes give rise to observable features including wrinkling, dyschromia, dryness, rough surface texture, rhytides, and keratosis. In general, the extent of photodamage is positively associated with the amount of exposure to ultraviolet (UV) radiation and is observed more commonly in lighter-skinned individuals. Skin pigmentation, more specifically melanin content, mitigates the effects of UV exposure in darker-skinned individuals (Fitzpatrick Type VI) having greater inherent photoprotection.

Treatment planning and outcome measurement

Plastic surgeons are highly skilled judges of skin damage with significant experience in a variety of techniques and strategies to restore the skin to a “chronologically” younger state. Visual methods are the foundation of clinical care and represent the gold standard for the assessment of skin color; however, assessment of the skin surface relies on clinical judgment. Several visual scales are used to characterize the extent of photoaging, evaluate treatment response, appraise improvement, and determine patient satisfaction. Unfortunately, none have been established as the universal standard for the evaluation of photoaging. Concomitantly, there are no widely accepted descriptions of normal skin. Drawbacks to visual methods of assessment include low reproducibility and variation in interobserver reliability. Although the human visual system is uniquely sophisticated and integrative, assessors are limited as to what they can see and palpate at the skin surface. Consequently, the effectiveness of specific interventions is difficult to determine qualitatively and quantitatively. As the health care system emphasizes evidence-based care, prevention, quality, and cost-effectiveness, the requisite for objective measures of the status of cutaneous disease is expected to increase.

Literature review: grading scales

Because photodamage affects the entire face, identification of a suitable “normal control” is a limitation of all grading scales. Table 1 illustrates the visually based methods described in the literature for use by patients and physicians. Visual grading methods commonly use descriptors such as slight, mild, moderate, and severe to indicate the severity of cutaneous damage and area (percentage) of involvement relative to nearby areas of normal skin. Scales for degree of cutaneous improvement and satisfaction use similarly vague terminology. The inherent problem with these scales is their subjectivity, in that they are not referenced against standards or quantitative change but rather rely on the evaluator’s beliefs. The frame of reference of the judge and the interpretation of these terms is another confounding variable. Logically it follows that analysis of the literature is difficult at best, limiting the applicability of treatment results. The limitations of subjective measurements and the global need for standardized objective measurements have been noted.

Alexiades-Armenakas and colleagues have constructed a more objective 8-point grading scale to encompass the attributes of facial photodamage, shown in Table 2 . This schema includes rhytides, elastosis, dyschromia, erythema/telangiectasia, keratoses, texture, and laxity, and can be used as a series of individual scales or as a global composite. Skin color is a feature considered in the assessment of elastosis and erythema. Hyperpigmentation in terms of number and area of spots is graded in the assessment of dyschromia. Textural dimensions include wrinkles, keratoses, and surface roughness. Mechanical properties of tissue are judged based on the presence of folds, jowling, and bands. The attribute scores are based on the extent of involvement and severity. Composite grading scales using high-quality photographic images have also been developed and validated. Specifically, these scales evaluate the effort required for treatment, identify the most problematic region, and estimate the subject’s age, thereby providing a framework for the application of objective modalities. The most important individual scales do vary according to sex; however, they do not include other attributes of importance in determining perceived age, namely, color uniformity, hyperpigmentation, red color (erythema), yellow color, or fine surface texture. Together, these grading scales serve as the clinical foundation for selection and application of objective, quantitative methods.

Quantitative objective measurement of skin characteristics

An essential component to delivering optimum outcomes and maximizing patient satisfaction in the treatment of facial photodamage is the capability to identify appropriate treatment modalities and set patient expectations of potential improvement. Arguably, both depend on the capability to measure facial characteristics before and after treatment. The following sections have as a backdrop these questions:

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  Are objective, quantitative methods more effective than subjective, experience-based assessment?

  
  
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  Can clinical judgment adequately predict the treatment effects on the skin at the histologic levels of the dermis, epidermis, and stratum corneum?

  
  
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  What is the relationship between findings from either the clinical examination or objective assessment and customer/patient perception of improvement?

  
  
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  Can this be used to predict the outcome of any given procedure for any given patient?

  
  
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  What is the effect of any particular treatment as a function of initial photoaging severity?

To be effective, objective measurements need to (1) determine whether a real change has occurred as a result of an intervention, (2) accurately show that a condition is different from the normal, (3) be valid as defined by correlating with the gold standard of visual clinical assessment, (4) be reproducible, and (5) be clinically feasible.