Purpose:
We examined how tear film stability and ocular surface status varies with subjective dryness ratings in soft lens wearers whose experience ranged from no to severe dryness sensation during lens wear.
Methods:
130 soft lens wearers [26 + 10 yrs, 32% M] were observed at 2 visits after 6+ hours of lens wear with a fresh pair of their habitual lens brand (24 types, including 5 SiH brands). Each subject was self-categorized into 1 of 5 classes of dryness experienced with lens wear according to the UC Berkeley Dry Eye Flow Chart (DEFC). Subjective dryness ratings for severity and frequency were gathered using a continuous visual analogue scale (VAS). In vivo lens surface wettability was evaluated using a slit lamp examination with white light and a diffuser. Pre-lens tear film stability was assessed by measuring non-invasive tear break-up time (NI-TBUT) in seconds (s) with a photokeratoscope. Reflected mire images were then taken 10 s after blink. Ring distortion and haze were graded 0-4 in the central, inferior, nasal, and temporal zones. Corneal and conjunctival fluorescein staining were evaluated after lens removal.
Results:
Average frequency and severity as measured on the VAS were directly and significantly related to the DEFC class (p<0.0001). NI-TBUT was significantly related to the DEFC class (p<0.001). For example, those with no symptoms (class 1) have a NI-TBUT 2 s longer than those with the worst symptoms (class 5). However, neither wettability nor mire distortion/haze were significantly related to DEFC class. The depth and type of corneal staining were also not significant factors whereas an increased corneal staining extent and conjunctival staining were associated with class 5.
Conclusions:
A VAS on dry eye frequency is a useful tool to classify patients from normal to mild and severe lens-induced dry eye. Although a difference of 2 s in NI-TBUT was statistically significant, this difference may not be clinically important. Interestingly, corneal and conjunctival staining play significant roles in dryness sensation with lens wear. Clinicians should consider a lens/solution combination that minimizes disruption on the ocular surface.
Keywords: contact lens • cornea: tears/tear film/dry eye • clinical (human) or epidemiologic studies: systems/equipment/techniques