Surgical site infections (SSIs) are a significant healthcare challenge, leading to increased patient morbidity, extended hospitalizations, and elevated healthcare expenditures. Among the myriad factors influencing the risk of SSIs one which has attracted relatively little attention to date is the cleanliness of patient footwear in the operating room (OR) environment.

The potential for footwear to act as a conduit for microbial dissemination has been previously reported in medical personnel by Treakle et al. (2009) who found that 55% of shoes are to be contaminated with methicillin-resistant *Staphylococcus aureus* (MRSA) [1] . Similarly, another study demonstrated that disposable shoe covers, when in contact with the surgical floor, accumulated significant bacterial loads, including live pathogens [2] . Tateiwa et al. (2020) investigated the impact of surgical clothing and footwear upon OR contamination, and the role of intraoperative movements in elevating airborne particle concentrations, finding a 20-fold increase in particle generation induced by movements [3] . Similarly, Brohus, Balling and Jeppesen (2006) reported a 10-fold increase in particle concentration due to personnel activity [4] .

This study endeavours to document the cleanliness of patient footwear in an ophthalmic day surgery setting and to highlight the potential impact.

Table 2 summarizes key findings and presents age distribution data for the overall patient population and by gender, along with logistic regression results analysing the relationship between shoe hygiene where grades A and B were compared to C, D and E and factors such as weather conditions and patient gender. The data provides insights into potential risk factors for poor shoe hygiene among ophthalmology patients, which may have implications for infection control practices in clinical settings.

Furthermore, the Cohen kappa score of 0.76 indicates that there was good agreement between the two reviewers.

The most common types of shoes observed among the 94 patients were smart shoes (n = 19), sneakers (n = 17), boots (n = 16) leather slip-ons (n = 10), runners (n = 10), sandals (n = 8), sliders (n = 3), pumps (n = 5), and trainers (n = 7). Smart shoes were more commonly worn by females (n = 12) and sneakers more commonly by males (n = 10). Smart shoes were predominantly worn in sunny and dry conditions (n = 14), while sneakers were more common in rainy/wet conditions (n = 10). Furthermore, leather smart shoes were found to be more prone to retaining dirt and mud compared to mesh or fabric uppers of sneakers, and shoes with textured soles were more likely to have embedded debris than those with smooth soles. Older/worn-out shoes also showed greater signs of contamination.

Table 3 provides a detailed analysis of shoe hygiene categorized by weather conditions and gender. The data highlights that Grade B is the most common across all categories, indicating generally clean shoes. There is a suggestion that rainy conditions were associated with slightly more debris. In contrast to the visual summary of the table, the logistic regression analysis revealed that male gender was significantly associated with poorer shoe cleanliness.

This study is the first to report upon the patterns in shoe hygiene among patients entering an ophthalmic operating room (OR). Most shoes in this study were in good condition but as expected gender differences were observed, with females more likely to wear smart shoes and males more likely to wear sneakers [5] [6] . Weather conditions affected shoe cleanliness, though the finding that poor hygiene was less likely in rainy conditions was not statistically significant identified in other work [7] [8] . These findings also suggest that the choice of shoe materials and design can significantly influence their hygiene [9] [10] . In addition, the study also demonstrated that male gender was associated with poorer shoe cleanliness.

Given the study’s relatively small sample size and an expected post-operative endophthalmitis rate of between 0.04% to 0.2% following cataract surgery [11] - [13] , conclusions related to infection rates were unrealistic; however, for completeness, screening for post-operative infections was performed, yielding no infections.

This study highlights an important and probably largely overlooked aspect of day-case surgery, in that patients, their clothing and hygiene, including the state of their shoes, probably constitute what has become an “acceptable” infection risk for which there currently appears little mitigation. Whilst we appreciate that even a very large study may fail to identify a causal link between the state of shoe contamination and post-operative outcomes, it is proven beyond doubt that cleanliness matters in the operating room environment. It takes no great leap of faith to extend this cleanliness to the patient. How far this is taken is the question, but from our observations, it is clear that improvements could be made, for example, removing outdoor shoes and providing disposable slippers or more simply by providing clean overshoes. These measures are supported by guidelines from the Centres for Disease Control and Prevention (2017) and the World Health Organization (2016) [14] [15] . Of course, these suggestions do nothing for other aspects of patient cleanliness/hygiene which are also probably worthy of investigation in their own right.

This study had several limitations, including its observational design and the relatively small sample size, but it serves very simply to highlight a potential problem which is right under our patients’ feet and for which simple measures are likely to be in every patient’s best interests.