Abstract
Purpose :
According to the TFOS DEWS II report, both TFI and neurosensory abnormalities play etiological roles in dry eye (DE). We have previously shown that repeated TFI or tear breakup (TBU), induced by Sustained TeAR Exposure (STARE) trials, altered sensory function in normal subjects. In this study, we investigate the role of repeated TBU by STARE trials on sensory responses to non-noxious cooling and noxious stimuli in DE subjects.
Methods :
Eight DE subjects completed the study. The cooling (20°C), and noxious mechanical and chemical stimuli (approximately 34°C on the ocular surface) were delivered by the IU Belmonte esthesiometer. Corneal detection threshold to cooling and mechanical stimuli were assessed respectively on two separate visits before, after, and 30 minutes following 5 consecutive STARE trials. Following the threshold estimation, sensations of intensity, coolness, irritation and pain to suprathreshold (1.25 and 1.5 times threshold levels) cooling and chemical stimuli were assessed using a 0 (none) to 100 (very strong) scale, before and 30 minuets after.
Results :
Following STARE, cooling thresholds appeared to increase initially then decreased 30 minutes after; a statistically significant difference between measurement time was observed (p=0.044, Figure 1). Mechanical threshold tended to decrease after STARE but the difference was not statistically significant. Regardless of measurement time, ratings of intensity, coolness and irritation to suprathreshold cooling stimuli increased with increasing stimulus levels (all P ≤ 0.045). Irritation to suprathreshold chemical stimuli showed a similar trend but the difference did not reach statistical significance (p=0.081). Post STARE, the intensity and coolness ratings to cooling stimuli tended to be lower while irritation to both suprathreshold cooling and chemical stimuli tended to be rated higher, although these differences were not statistically significant.
Conclusions :
This study showed altered detection threshold to cooling stimuli and increased irritation with increasing suprathreshold cooling stimuli in DE subjects following STARE, suggesting an effect on neurosensory function. These results, taken together with those from normal subjects, suggest that there may be a causal link between TFI and neurosensory abnormities. Further investigation with larger sample size of DE subjects is warranted.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.