Outcomes in Acute Ocular Surface Chemical Injury-Role of pH Measurement on Presentation: A Retrospective Cohort Study.

INTRODUCTION

Chemical eye injury is an ophthalmic emergency which can lead to loss of vision. We aimed to determine the prognostic value of tear film pH on presentation in acute chemical eye injuries.

METHODS

Demographics, pH values, causative chemical, injury circumstances, injury severity, and clinical and visual outcomes were assessed from previously collated data from patients presenting to the emergency eye department (EED) in a UK tertiary hospital. All patients who had pH measured before irrigation in the EED were included. Associations with injury severity and clinical and visual outcomes were analysed.

RESULTS

Pre-irrigation pH was recorded in 135 eyes (113 patients, 66.4% male, mean age 35.5 years [range 2-78; standard deviation (SD) 15.4]; 15 acid, 108 alkali, 12 unknown). The pH within 24 h of injury (n = 108 eyes) correlated significantly with injury severity (r = 0.20, p = 0.02). In patients with abnormal pH on presentation (n = 26 eyes), pH correlated strongly with injury severity (r = 0.72, p < 0.01). There was no significant correlation with visual outcome at follow-up (n = 70 eyes, 60 patients, follow-up 1-3929 days, mean 579.4 days, SD 1206.0 days; r = 0.12, p = 0.11). Presenting pH below 6.5 or above 7.5 was a significant predictive factor for the presence of limbal stem cell deficiency (LSCD) (univariate binary logistic regression analysis, p = 0.026, Nagelkerke R-squared = 0.090).

CONCLUSION

Deranged pH correlated with burn severity in patients presenting within 24 h of injury and was a significant predictive factor for LSCD.