Continuous measurement of high-order aberrations after blinking in dry eye patients

OBJECTIVE: To study the continuous changes after blinking of the total eye high-order aberration (HOA) in dry eye patients.

METHODS: The total eye height aberration (HOA) of 20 eyes of 20 dry eye patients was continuously measured using a wavefront aberrometer and each measurement lasted for 30 seconds. Twenty eyes were divided into two groups according to whether the superficial punctate keratopathy (SPK) occurred in the central cornea. During the measurement, subjects were asked to blink once every 10 seconds. Analyze the aberration data within the 4mm diameter of the pupil center, including quasi-like aberrations, spherical aberrations, and total higher-order aberrations (up to the Zernike polynomial sixth order). The total HOA and the total HOA's Volatility Index (FI) and Stability Index (SI) were compared between the two groups. Investigate the continuous changes in coma aberrations, spherical aberrations, and total HOA.

RESULTS: Total eye HOA was significantly (P = 0.001) higher in dry eyes with central SPK than in dry eyes without central SPK. The continuous pattern of total eye HOA of dry eyes with central SPK had higher initial values and continued higher values, whereas dry eye without central SPK showed consistently lower total HOA, similar to the normal eye pattern.

Conclusion: The increase in dry eye HOA is attributable in part to the SPK above the visual area. Low tear fluid levels in dry eyes may not result in a continuous increase in HOA after blinking. Continuous measurement of HOA may help to assess continuous changes in the visual quality of dry eye patients. (Invest Ophthalmol Vis Sci. 2008;49:133-138) DOI: 10.1167/iovs.07-0762

Dry eye has been regarded as a disease that hardly affects visual function, except in severe cases. 1 However, recent studies have shown that the visual quality of dry eye is impaired compared with normal eyes. 1-6 It can be imagined that the unstable and irregular tear film of dry eye breaks on the irregular ocular surface, especially in the case where the blinking of the patient is prohibited. Studies that performed functional visual acuity measurements showed that functional visual acuity was compromised in patients with dry eye during fixation. 1-5 Moreover, in several studies, researchers measured continuous corneas in normal and dry eyes.

Topographic map data or corneal and total-eye wavefront aberrations show that dynamic changes in the tear film affect visual quality after blinking, and the visual quality of 7-15 dry eyes is also confirmed. 7-9 Recent studies have shown that corneal high-order aberrations (HOAs) tend to increase after blinking in dry eyes, and that the total eye and corneal HOA are significantly higher than in normal eyes. 6-9 However, little is known about the continuous change after a blink of the HOA. It is interesting to note how the surface of an irregular cornea with an unstable tear film affects the post- blinking change of dry eyes of the full eye HOA. Therefore, we conducted this prospective study to investigate the continuous changes in the eye blink of the eye in patients with dry eye.