Spatial frequency domain imaging of the oculofacial region in control patients

Spatial frequency domain imaging (SFDI) is a wide-field optical imaging modality that applies patterned illumination at multiple center wavelengths (470 to 851nm) to quantify the properties of subsurface tissue in vivo. Imaging of the periocular region will guide diagnostic and therapeutic decision making in inflammatory and infiltrative conditions by quantifying parameters such as tissue oxygen saturation and hemoglobin concentration. We previously used a fabricated tissue simulating facial phantom to study the geometric impact of complex ocular adnexal anatomy inherent to the periocular region and identified robust and accurate regions of interest (ROI) by which to image patients. Twenty-five control patients were imaged under an approved IRB protocol using the Reflect RS™ (Modulim, Inc., Irvine, CA) to measure calibrated diffuse reflectance images over a 15 x 20cm 2 field of view, with a spatial resolution of ~0.5mm. “En face” and “side profile” views were captured along established regions of interest (ROIs): inferior temporal quadrant (ITQ), inferior nasal quadrant (INQ), superior temporal quadrant (STQ), and forehead (control), as well as a cast polydimethylsiloxane-based tissue-simulating reference facial phantom with known optical properties as a geometric control. The normative range for μ′s and μa values for periocular and forehead ROI are presented. Measurement angle did not significantly impact the measured optical properties. Data from the pool of measured subjects demonstrated an increase in μa with increasing Fitzpatrick score, whereas μ′s reduced with increasing Fitzpatrick score, consistent with previous findings. This is the first study to quantitatively characterize normal human periocular skin using SFDI across a range of skin types. Measurements were robust to imaging angle but varied with Fitzpatrick score.