Eye-tracking – A first step towards an automated measure of success in cleft lip surgery

Repair of a cleft of the lip leaves a scar, and nearly always some visible difference in appearance of the lip such as asymmetry. Such differences in appearance can cause significant distress so it is important that surgery results in the ‘best’ outcome possible.

However, in order to know which method of lip repair gives the best outcomes, it is necessary to have a way of measuring how good the outcome of a lip repair is. At the moment studies which look at how good the outcomes of cleft lip repair are mainly use photographs. They measure the quality of the outcome by asking viewers to rate the quality of the repair. This is a subjective way of measuring and depends on the viewers using the same criteria in their assessment. It has been shown that assessing the outcomes of lip repair surgery using these sorts of measuring tools gives unreliable results which are difficult to repeat with the same result.

The researchers in this study want to use a more objective way of measuring lip repair outcomes, by looking at eye tracking. Eye tracking records the path the eyes take when looking at something. It is already known that people scan a face with their eyes in a particular way: there is a regular and predictable ‘scanpath’. The researchers hypothesise that a cleft of the lip will disrupt this usual scanpath, and that the better the repair, the closer to normal the scanpath will be after surgery.

In this initial study, the researchers will compare the scanpath of viewers looking at photographs of babies with an unrepaired cleft lip to the scanpath of the same viewers looking at photographs of the same children soon after their cleft lip repair and at 5 years of age. The aim is to see if the eye tracking technique can reliably differentiate between children with repaired and unrepaired clefts of the lip.

The researchers will also look to see if the amount of disruption of the usual scanpath is related to the ratings given to the lip repair using the more traditional subjective techniques. They hypothesise that a repaired cleft lip given a good subjective rating will have less disruption of the usual eye-tracking scanpath than a repaired cleft lip given a poor subjective rating.

This is the first stage of a developing an objective method of measuring the quality of a cleft lip repair.

This is a one year project supported by CLEFT and we hope to publish results in early 2024.