Measuring the Tympanic Membrane Thickness Using Optical Coherence Tomography

Introduction: the average thickness of the tympanic membrane (TM) normally fluctuates around 100 µm. Most of the measurements of the TM thickness presented in previous works were performed on cadaveric material. The anatomical parameters of the TM can be measured using optical coherence tomography (OCT). Materials and methods: we used spectral-domain OCT with a non-contact probe to study the structures of the middle ear. The results of OCT examination of 58 tympanic membranes of patients without middle ear pathology were analyzed. Quantitative analysis of OCT images was performed using the ImageJ program. The thickness of the tympanic membrane was calculated manually at 5 randomly selected points. To convert optical values into metric ones, we used an average refractive index of 1.45. Results: the TM thickness in patients without ear pathology was 138 µm (±29). Conclusions: OCT is an effective method of non-invasive examination of the TM and can be successfully used to measure the TM thickness. Improving the algorithms for processing OCT images in order to automatically calculate the TM thickness and make TM topographic maps remains a crucial task and its solution is expected to significantly improve the diagnostic properties of the method.