Purpose:

MGD patients undergoing a series of IPL treatments reported increases in their ocular symptoms during the severe forest fire season of 2017. We noticed a slower rate of improvement in MMP-9 testing during this period and hypothesized that the Air Quality Index (AQI) might correlate with hindered improvements in the inflammation marker MMP-9.

Methods:

This retrospective clinical study involved 72 patients in one center with one physician and one operator. Patients received a series of 1-6 treatments at varying intervals; most patients received 1-4 treatments. Standard Patient Evaluation of Eye Dryness (SPEED) questionnaires, osmolarity testing, MMP-9 testing (InflammaDryR) and slit lamp examinations were performed. Both SPEED and MMP9 were analyzed. Air quality, session number, and weeks since last session were considered as possible explanatory variables. Due to non-normality, SPEED was log-transformed. Air quality was removed from the final model for SPEED (t56=0.2061, p=0.8375).

Results:

For a typical patient with an MMP9 of 1 or greater,MMP9 decreases by 0.5160 per session for sessions conducted at the same air quality (t85=-3.2995, p=0.0014) with an associated 95% confidence interval of (0.2051,0.8270). For a one level decrease in air quality at a fixed session number, MMP9 is expected to increase by 0.3381 (t85=2.3838, p=0.0194) with an associated 95% confidence interval of (0.0561,0.6202). Effects plots for both session number and air quality are shown in Figure 1. The effect of air quality on fitted values for MMP9 is shown for Figure 2.

Conclusions:

IPL treatment series is associated with improved osmolarity and MMP-9 levels, however, at a fixed session number, a one level decrease in air quality (i.e. moderate to poor) is found to yield an estimated 0.3381 decrease in MMP9 levels, which demonstrates an association between poor quality and hindered decrease in MMP9 levels