Abstract:

The dynamic changes of tear film in morphology include the changes in the tear film thickness, lipid layer and pattern of tear film break up. Dry eye is often accompanied with the symptom of visual disturbance. The impact of the tear film on the quality of the retinal image depends greatly on the homogeneity of the tear pellicle. We reviewed the studies assessing the effect of tear film dynamic changes on the optical quality by serial measurement of high order aberrations (HOA) and forward light scatter using Hartmann-Shack wavefront sensors and Optical Quality Analysis Systems (OQAS) in a noninvasive and quantitative fashion on healthy and dry eye patients during steady gaze after a blink as well as post the application of artificial tears. Results showed that the optical quality might deteriorate in clinically asymptomatic subjects when suppressed blinking, the variation of the temporal changes in ocular HOA and objective scatter index (OSI) shared similar features with symptomatic dry eye. The dynamics of tear film change are accelerated in dry eye, both HOA and OSI are significantly greater than those in normal eyes. After long term artificial tears instillation, the postblink optical quality is significantly improved due to the improvement in tear stability. Serial measurements of the optical quality can reflect temporal changes in  the tear film, having the potential applications for detecting preclinical phase of dry eye disease in asymptomatic subjects.