Effect of a single warm compress prior to ophthalmic surgery on ocular surface and intraoperative visibility: a randomised controlled study

PURPOSE: We investigated the effects of a warm compress immediately before surgery on the ocular surface and intraoperative visibility during surgery. METHODS: A randomised controlled quasi-experiment at Saitama Medical University Hospital. From November 2020 to September 2021, 200 patients scheduled for endophthalmic surgery were randomly assigned to a group that received a hot compress with a spontaneously heating eye mask (HM group) or a group that received only an eye mask (control group). The eye masks were applied for 20 min from 2 hours before surgery, and before and after mask application in the non-invasive tear break-up time (NIBUT), tear meniscus height (TMH) and obstruction score of the meibomian gland (meiboscore) were evaluated. The time from wetting to dry blurring of the corneal surface (corneal blurring time, CBT) was also compared before and after the warm compress. RESULTS: We enrolled 100 patients in the HM group (mean age 69.0±13.3 years) and 99 patients in the control group (mean age 69.5±16.2 years). In the control group, there were no significant changes in the NIBUT, meiboscore or TMH before and after eye mask use, whereas in the HM group, the NIBUT increased from 6.7±5.1 to 9.5±5.6 s (p<0.001), the meiboscore improved from 0.71±0.93 to 0.63±0.96 (p=0.03) and the TMH significantly improved from 0.22±0.08 to 0.24±0.08 mm (p<0.001). The CBT was longer the HM group than control group (33.5±13.4 s, 25.7±14.9 s, respectively, p=0.01). CONCLUSIONS: The condition of the ocular surface and intraoperative visibility improved after a single warm compress. TRIAL REGISTRATION NUMBER: UMIN R000047286.