Effectiveness of VISIA system in evaluating the severity of rosacea

Rosacea is a facial chronic inflammatory skin disease with almost 5.5% prevalence. Although there are various scales of rosacea, they are objective and discordant among different dermatologists. Noninvasive objective measurements such as VISIA system might play essential roles in the diagnosis and evaluation of rosacea. Here, we intended to reveal the effectiveness of VISIA system in rosacea.

are numerous scales of rosacea, those scales are subjective and not reliable.
A noninvasive measurement technique provides a novel method for diagnosis and evaluation of skin diseases without damage. Noninvasive tools have been applied for the diagnosis and estimation of different skin disorders, such as scars, 7 vitiligo, 8 melanoma, 9 acne, 10 psoriasis, 11 eczema 12 and port wine stain. 13 The emerging imaging technology, serving as one of these important noninvasive methods, is beneficial for dermatologists to diagnose and evaluate patients precisely and rapidly. VISIA system (Canfield Scientific, Parsippany, NJ, USA) is a common noninvasive imaging system, available to capture high-resolution facial images. 9,14 By using quantitative analysis software (RBX; Canfield Scientific), the VISIA system separates red and brown channels and enables a better visualization of erythema and telangiectasia. 15 In this article, we compared VISIA parameters with physician's subjective assessments and analyzed their correlations to clarify the effectiveness of VISIA system in evaluating rosacea. and muscular, and immune system diseases) were excluded.

Measurements
All participants received front, left and right sides of full-face images

Physician's assessments (PSA)
One certified dermatologist assessed patients' standard images according to five scales, respectively, including investigator global assessment (IGA), 16

Statistical analysis
Spearman correlation analyses between VISIA parameters and physician's assessment (PSA) were determined by Stata 16.0 software.

Study flow and demographic characteristics
A number of 611 subjects were screened, and 563 of them entered the study ( Figure 2

Correlations between PSA and red area
All three indexes (feature count, absolute score and percentile) of red area in the left and right faces had significant correlations with IGA and CEA, whereas our study showed no significant correlation between PSA and feature count of red area in the front face (  (Table 3). Although there was no significant correlation between red area and IGA (or CEA), feature count of red area in the front face displayed significant correlation with numerical score, NRS and telangiectasis.
Except the absolute score of red area in the front face, the absolute score in the left and right side had higher r value in male rosacea patients than in female rosacea patients (Table 4).
Similarly, the feature count and percentile of red area in male TA B L E 5 Correlation analysis between physician's assessment (PSA) and red area in different ages In order to study correlations among different age groups, we divided all patients into six groups (Table 5). Participants between 51 and 60 years demonstrated the highest r value between red area and IGA (or CEA), whereas there seemed no significant correlation between red area and PSA in rosacea patients aged lower than 20 or older than 60.

Correlations between PSA and other parameters
Genome-wide association study discovered that skin pigmentation genes were associated with rosacea severity. 19 Spot, UV spot and brown spot represent the pigmentation parameters in VISIA system. Thus, we analyzed the correlations between red area and other VISIA parameters and found that spot, UV spot and brown spot were correlated with red area, with the highest r value in brown spot (Table 6). Then, we demonstrated that brown spot showed significant association with IGA (or CEA) ( Table 7).

DISCUSSION
This study revealed that left-and right-side faces of red area in VISIA system were effective in assessing rosacea, especially ery- and rosacea. [26][27][28][29][30][31][32][33] Here we first demonstrated the correlation between PSA and VISIA system and highlighted the erythema-directed red area when evaluating rosacea patients. Unfortunately, VISIA system concentrates on the whole image rather topical area, and it could not segment diffuse erythema. Xu combined ImageJ and VISIA system and proposed a simple and precise method to analyze topical erythema. 34 Besides VISIA system, IPP from Media Cybernetics, 35 CSKIN from Yanyun Technology 36 might also be effective in evaluating rosacea. Compared with VISIA system with RGB space, CSKIN used CIELAB color system, which is currently the most widely-used space, indicating better reliability in assessing rosacea. 36,37 Despite VISIA system, there are other imaging methods applied in assessing severity of rosacea, including reflectance confocal microscopy (RCM), dermoscopy, capillaroscopy, optical coherence tomography (OCT), ultrasonography and infrared photography. 9,[38][39][40] Among those imaging techniques, RCM and OCT are used for monitoring Demodex mites in rosacea, whereas dermoscopy and capillaroscopy were applied for telangiectasis in rosacea. Recently, optoacoustic imaging was regarded as a novel tool to measure highresolution hemodynamic changes in microvasculature for monitoring inflammatory skin disorders. 41 Computer-assisted diagnosis techniques also broadened our knowledge of noninvasive measurements in rosacea. 42,43 Although those noninvasive tools seem promising in the assessment of rosacea, adequate and validated clinical trials are needed for further investigation.

CONCLUSION
In conclusion, VISIA system is an effective noninvasive imaging technique for the assessment of rosacea, particularly in ETR patients. Red area in the left and right faces would be an additional measurement when evaluating the severity of erythema in rosacea patients.