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Gu JT, Hu A, Oh C, Wong BJF. A New Method for Photocephalometry. JAMA Facial Plast Surg. 2018;20(1):81–82. doi:10.1001/jamafacial.2017.0426
Whereas 3-dimensional surface imaging and stereophotogrammetry allow plastic surgeons the unparalleled ability to perform quantitative and morphometric analysis, digital still photography remains the mainstay in aesthetic photodocumentation as a result of lower cost and wider adoption.
Standard still photographs are obtained by positioning the patient in standard facial views for accurate preoperative and postoperative facial analysis. Although this method provides accurate assessment of facial ratios (ie, nasal projection according to Goode, Simons, or Crumley), whole measurements, such as radix proportion, may not meaningfully be translated from photographs to operating room table.1-4 As a solution, patients may be instructed to hold a ruler while images are obtained. This process can be surprisingly challenging for many patients and is unnecessarily cumbersome for the nonexpert photographer.
We present a simple, cost-effective technique for obtaining preoperative and postoperative cephalometric measurements from digital facial photographs using an adhesive ruler affixed to sunglasses.
Consent for photography was obtained prior to obtaining photographs. Approval from the University of California Irvine Institutional Review Board was not sought because this technique is exempt from review as it does not involve any intervention or risk of loss of sensitive information.
Prior to obtaining photographs, subjects are given ruled sunglasses positioned above the trichial line and displacing any hair away from the forehead and face (Figure). A second ruler is held in close approximation to the desired plane of imaging as a calibration standard. Sunglasses were affixed with millimeter rulers on frontal and lateral aspects. Photographs were taken in frontal, lateral, and three-quarters views along the Frankfort horizontal plane, with a tripod-mounted digital single-lens reflex camera using a 105-mm macro lens and camera-mounted flash under standardized conditions. Care was taken to maintain fixed distances and consistent positioning.
The pixel length of 1 cm for each ruler was digitally measured using ImageJ, version 1.50i (National Institutes of Health), with 10 measurements on each ruler. Paired-samples t tests were conducted using SPSS, version 21 (IBM Corporation) for measurements of the ruled sunglasses and calibration standard for each of the views of the face.
Mean, standard deviation, percent difference, and paired-samples t test of pixel length measurements are provided in the Table. There was no significant difference in mean (SD) measurements between the ruled sunglasses and the calibration standard from frontal right-mounted flash (92.93 [0.08] vs 92.84 [0.31] pixels; P = .61), left-mounted flash (93.78 [0.48] vs 93.28 [0.34] pixels; P = .29), right-lateral (121.52 [1.10] vs 122.07 [0.24] pixels; P = .23), and left-lateral views (96.68 [0.57] vs 97.27 [0.17] pixels; P = .14). Percent differences for the aforementioned views ranged from 0.11% to 0.61%. For both three-quarters views, there was a significant difference between mean (SD) pixel lengths: right, 114.52 (0.33) vs 109.72 (0.63) (difference, 4.29%; 95% CI, 3.57%-5.01%; P < .001), and left, 116.27 (0.73) vs 112.85 (0.64) (difference, 2.99%; 95% CI, 2.10%-3.87%; P = .003).
Using a pair of sunglasses modified to include an affixed ruler, we were able to accurately obtain anthropometric measurements for facial analysis and operative planning. The differences in measurements between ruled sunglasses and the calibration standard for both three-quarters views is most likely accounted for by user error. A small change in the angle θ of the calibration standard away from the mid-sagittal plane of the head would lead to a distortion in measurement of the ruler proportional to cosθ. Deviations in other planes away from the imaging plane would yield similar distortions. Because the ruled sunglasses are fixed in motion with the head, measurements obtained using the sunglasses method are more reliable than previous standards such as the handheld ruler. Further limitations include access to 3-dimensional surface imaging, lens distortion, and sample size.
Digital photography has become widely available, and standard facial views allow for consistent preoperative documentation, operative planning, and postoperative outcomes analysis. Our method of using ruled sunglasses is cost-effective and reliable and removes reliance on the patient during facial photography. This is an easily adopted approach that augments photodocumentation with quantitative measures and may translate to measurable improvements in outcomes.
Corresponding Author: Brian J. F. Wong, MD, PhD, Department of Otolaryngology–Head and Neck Surgery, University of California Irvine, 1002 Health Sciences Rd, Irvine, CA 92617 (email@example.com).
Accepted for Publication: March 2, 2017.
Published Online: November 2, 2017. doi:10.1001/jamafacial.2017.0426
Author Contributions: Dr Wong had full access to all the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.
Sudy concept and design: Gu, Hu, Wong.
Acquisition, analysis, or interpretation of data: All authors.
Drafting of the manuscript: Gu, Hu.
Critical revision of the manuscript for important intellectual content: Gu, Oh, Wong.
Statistical analysis: Gu, Hu.
Obtained funding: Wong.
Administrative, technical, or material support: Hu, Oh, Wong.
Supervision: Gu, Wong.
Conflict of Interest Disclosures: None reported.
Funding/Support: Funding for this study was provided by department funds of the Department of Otolaryngology–Head and Neck Surgery, University of California, Irvine, for data acquisition, statistical analysis, and software use.
Role of the Funder/Sponsor: The funding source had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.
Additional Contributions: We thank Connie Oh, BA, Beckman Laser Institute, University of California Irvine, for granting permission to publish her likeness, and Prem Tripathi, MD, Department of Otolaryngology–Head and Neck Surgery, University of California Irvine, for his revisions of the manuscript. No compensation was received from any funding sponsors for these contributions.
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