HYPOTHESIS: Higher light intensity settings do not yield improved image quality in endoscopic ear surgery. BACKGROUND: Light intensity is a parameter with major impact on the quality of digital images. For ear surgery, light produces heat associated with a thermal risk to ear structures and the light source setting should be accordingly optimized. METHODS: Several series of still images were acquired during live middle ear surgery, using cadaveric and plastic temporal bone models and with three-dimensional printed models. Images obtained under varying light intensities were compared with the image acquired at maximum intensity of a light emitting diode light source. We analyzed digital image brightness and noise using quantitative methods. RESULTS: Our measurements revealed significantly decreased image brightness with light intensities set below 20% with an increase in noise at light intensities lower than 30%. CONCLUSION: The optimal light source setting corresponded to 30% intensity in our experimental set-up. Special attention should be given to those cases where faster image quality degradation is expected (dark or bloody scenes or larger cavities). The results were strongly dependent on the equipment used. The methods described in this study can serve as a general guide for determining the optimal light source setting in any specific set-up.

Palacky University Olomouc Faculty of Medicine and Dentistry Department of Medical Biophysics

Palacky University Olomouc Faculty of Medicine and Dentistry Institute of Molecular and Translational Medicine Czech Republic

Palacky University Olomouc Faculty of Science Department of Computer Science

University Hospital Olomouc and Palacky University Olomouc Faculty of Medicine and Dentistry Department of Otorhinolaryngology and Head and Neck Surgery

See more in PubMed

Tarabichi M. Endoscopic middle ear surgery. Ann Otol Rhinol Laryngol 1999; 108:39–46.

Salzman R, Bakaj T, Herman J, Starek I. Endoscopic ear surgery – review. Otorinolaryngologie a Foniatrie 2016; 65:184–187.

Salzman R, Starek I, Herman J. Multiple cerebral venous thrombosis after endoscopic stapedotomy: a potential role of endoscope-produced heat. Acta Oto-Laryngol Case Rep 2017; 2:21–25.

Kozin ED, Lehmann A, Carter M, et al. Thermal effects of endoscopy in a human temporal bone model: implications for endoscopic ear surgery. Laryngoscope 2014; 124:E332–E339.

McCallum R, McColl J, Iyer A. The effect of light intensity on image quality in endoscopic ear surgery. Clin Otolaryngol 2018; 43:1266–1272.

Steiner M, Bormet J, Sharma G. Endoscopic Video System with Dynamic Contrast and Detail Enhancement. United States Patent Application 20140184916. July 3, 2014.

Immerkær J. Fast noise variance estimation. Comput Vis Image Underst 1996; 64:300–302.

Gonzalez RC, Woods RE. Digital Image Processing. 3rd ed2008; Upper Saddle River: Pearson, ISBN 9780131687288.

Lu ZM, Guo SZ. Lossless Information Hiding in Images. 2017; Amsterdam: Syngress, ISBN 9780128120064.