Abstract:
We have shown that dry eye patients respond to the Controlled Adverse Environment (CAE) by exhibiting symptoms only (19% of population), signs only (18% of population), or both symptoms and signs (63% of population). It has been hypothesized that these responses correlate with the stage of dry eye. For example, symptoms only patients may have early–stage dry eye; signs only patients may have late–stage dry eye; and symptoms and signs patients may have mid–stage dry eye. This study examined the relationship between a dry eye patient’s response to the CAE and the duration of their dry eye diagnosis.
Two–hundred and eighty–nine (289) patient eyes with a positive diagnosis of dry eye underwent baseline examinations consisting of a medical history, slit–lamp biomicroscopy, tear film break–up time and fluorescein staining. Patients were exposed to a CAE for 90 minutes, regulating humidity (< 10%), temperature (76 ± 6º F), airflow (non–turbulent), lighting conditions and visual tasking (watching a movie). Subjective evaluations of ocular discomfort were recorded using a standardized 0–4 scale during exposure. Upon exiting the CAE, the clinical signs were re–evaluated.
The following table shows a significant difference in the duration of a dry eye diagnosis between symptoms only and signs only dry eye patients (p < 0.0001).
The data suggest that in this population there is a correlation
between the signs and symptoms of dry eye and the duration of
dry eye diagnosis. A possible explanation is that corneal sensitivity
decreases over time in patients diagnosed with dry eye which
would effect sensation and compensatory mechanisms (e.g. reflex
tearing, increased mucin production, and blinking). This would
perhaps be related to the effect of chronic inflammation on
corneal sensation. An investigation of corneal sensitivity within
these groups is underway.
Keywords: cornea: tears/tear film/dry eye