In many developing parts of the world, colposcopy supplemented by aceto-whitening remains the most widespread means of reliably diagnosing cervical dysplasia, potentially leading to cervical cancer. The use of aceto-whitening to enhance detection rates for Barrett's esophagus is also emerging in recent years. Here we quantitatively study the aceto-whitening phenomenon using 1300 nm optical coherence tomography. By exposing a simple epithelial tissue model (excised rabbit cornea) to 0.5 M acetic

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... acid we report for the first time to our knowledge the direct measurement of the time over which the cellular brightening effect propagates down through the epithelial layer and into the stroma (~50 s). We also measure the magnitude of the cellular brightening effect in quantified units (~10 dB in the epithelium). We also exposed the rabbit corneas to two control substances for clinical aceto-whitening, 0.5 M lactic acid and phosphate buffered saline. Phosphate buffered saline produced no discernible change in the optical properties of the corneas. However we noted that lactic acid (an alpha-hydroxy acid) produced a pronounced brightening in the epithelial layer also, peaking at 8 dB after 20 s. The main distinction with acetic acid was a lack of effect in the corneal stroma. This may point to a way of giving OCT imaging the ability to discriminate between cells of epithelial vs fibroblastic phenotype.