Purpose:
The cornea is a unique and complex tissue that refracts and transmits light to the lens and retina while providing protection for inner ocular structures. The central 5 mm of the cornea and pre-corneal tear film account for at least two-thirds of the refractive power of the human visual system. This study was designed to investigate impairment of visual function consistent with central corneal staining.
Methods:
One hundred and six (106) eyes were evaluated: 54 eyes with central corneal staining and 52 control eyes with no central staining (central corneal staining scores of 0). Outcome measures included tear film break up time, fluorescein staining, and a series of visual function tasks including the inter-blink interval visual acuity decay (IVAD), reading rates, glare test, and BCVA (ETDRS). Patients also completed the Ocular Surface Disease Index (OSDI).
Results:
Patients with central corneal staining maintained their BCVA for a shorter amount of time (M=6.23sec, SD=4.31sec) during an extended inter-blink interval (without ocular anesthetic) than those without central staining (M=9.20sec, SD=8.91sec) as measured by the IVAD, p=.026. Patients with central staining also had longer reading rates (M=12.60sec, SD=4.51sec) than those without central staining (M=10.21sec, SD=3.04sec), p=.02. Data from the questionnaire measures demonstrated that patients without central staining had higher scores on the OSDI (M=6.73, SD=4.62) than those with central staining (M=4.47, SD=3.09), p=.006.
Conclusions:
This data shows that dry eyes with central corneal staining have more profound visual function deficits than those without central corneal staining.
Keywords: cornea: epithelium • visual acuity • cornea: tears/tear film/dry eye