Discussion

Our study highlights that clinicians are poor at visually estimating perforation size. Hampal et al. first compared visual estimation against an objective drawing and found greater clinical experience did not improve accuracy of estimation, with SHOs performing best, followed by registrars and finally consultants.^{Reference Hampal, Padgham, Bunt and Wright3} Our findings are similar to those of Hsu et al. who reported that registrars were more accurate than consultants, but they did not include SHOs in their study whilst we found no statistical significance between registrars and consultants.^{Reference Hsu, Chen, Hwang and Liu4} Regardless, in our study, the average difference between visual estimation and the ImageJ calculation derived by a consultant otologist was large for all groups, including registrars who were still on average inaccurate by 10 per cent.

Accurate estimation of perforation size can support parent or guardian counselling regarding conversative versus surgical management of their child's tympanic membrane perforation. Perforation size has been shown to be the single most important factor in spontaneous closure and therefore a more accurate tool of assessment is needed to aid patient counselling on the likely prognosis.^{Reference Jellinge, Kristensen and Larsen8} However, other patient factors such as active infection and contralateral otitis media with effusion, and surgical factors such as surgeon experience, can influence myringoplasty outcomes and should be considered.^{Reference Hardman, Muzaffar, Nankivell and Coulson2}

ImageJ has been described as a reliable method for tympanic perforation estimation which is freely available to download.^{Reference Ibekwe, Adeosun and Nwaorgu5} Ibekwe et al. found it to be devoid of inter-observer variability between two experienced otologists. In clinical practice, patients with tympanic membrane perforations may be reviewed by clinicians of different grades and the reliability of ImageJ within these groups has not previously been studied.^{Reference Ibekwe, Adeosun and Nwaorgu5} We found that the ImageJ calculations by all grades were more accurate than visual estimation. The differences among the groups using ImageJ were small and not statistically significant, suggesting that ImageJ can be reliably used amongst clinicians of varying experience.

The accuracy of tympanic membrane perforation calculation using ImageJ depends on high-quality photos using an otoendoscope and a computer system to record and download images prior to upload onto ImageJ. One described potential limitation of an otoendoscope is the inability to focus the entire rim of the tympanic membrane in one single image.^{Reference Ibekwe, Adeosun and Nwaorgu5} A previous study using cadaveric temporal bone models widened the external auditory canal to ensure the tympanic membranes were photographed occupying only the central three-quarters of the field of view.^{Reference Hampal, Padgham, Bunt and Wright3} Young children are less compliant with examination and multiple attempts to capture high-quality, in-focus images may be futile. In addition, uploading and tracing the image on ImageJ is time consuming and potentially unfeasible within a patient's allocated clinic slot.

Otoendoscopy provides additional benefits for the clinical consultation. Image capture allows clinicians to compare their current findings to previous examinations particularly if they have not assessed the patient previously themselves. Furthermore, traditional examination with an otoscope or microscope excludes the patient or carer from observing the examination. Otoendoscopy, however, allows the clinician to share their findings and therefore engage the user.^{Reference Wong, Schwam, Arrighi-Allisan, Fan, Perez and Cosetti9} Wong et al. found that adults reported greater satisfaction regarding communication and technical quality when video otoscopy was utilised in an out-patient clinic compared to standard microscopy.^{Reference Wong, Schwam, Arrighi-Allisan, Fan, Perez and Cosetti9} In the paediatric population, improved parental satisfaction and patient centeredness with video-endoscopy was found with children examined in the emergency department.^{Reference Rimon, Avraham, Sharabi-Nov, Luder, Krupik and Gilbey10} The use of video-otoscopy or video capture at a high rate per frame with direct upload to ImageJ may negate some limiting factors to support its introduction into daily clinical practice.

Our study is limited by the small number of images of similar perforation sizes in similar positions which do not reflect the full spectrum of perforations clinicians will encounter. Whilst variation in perforation size may affect the accuracy of visual estimation, we do not expect it to affect the ImageJ calculation and therefore still consider ImageJ a reliable tool for assessment. A paediatric consultant otologist's ImageJ results were selected as the gold standard which can be subject to error. The authors justify the choice of gold standard, given the reliability of results by consultant otologists demonstrated by Ibekwe et al.^{Reference Ibekwe, Nwaorgu, Adeosun, Kokong, Lawal and Okundia7} In their study, two consultant otologists reviewed 100 tympanic membranes using ImageJ software and conventional direct vision otoscopy and found the latter to be devoid of inter-user error.