Optical quality in patients with dry eye before and after treatment

Dry eye disease could result in vision-related subjective symptoms even in patients with good best-corrected visual acuity. The standard deviation of corneal power and the surface asymmetry index could be indicators of treatment efficacy in dry eye.

Few studies have examined changes in optical quality before and after dry eye treatment. Here, we evaluated changes in optical quality in patients with dry eye before and after treatment and identified potential indicators of dry eye-treatment efficacy.

Twenty-five right eyes of 25 untreated patients with dry eye were included. The same ocular-surface and optical-quality examinations were performed before and after two-weeks of treatment with hyaluronate in conjunction with fluorometholone eye drops. The Ocular Surface Disease Index, tear film break-up time, and corneal fluorescein staining were measured. Contrast sensitivity was used to measure resolution capability, the double-pass Optical Quality Analysis System to examine the modulation transfer function, Strehl ratio, and objective scattering index, and OPD Scan III to measure anterior corneal aberrations over 4-mm analytical zones including total corneal and high-order aberrations. The standard deviation of corneal power, surface regularity index, and surface asymmetry index were also measured. Paired sample t-tests and Spearman's correlations were used for the analyses.

The Ocular Surface Disease Index, tear film break-up time, and corneal fluorescein staining improved after two weeks of treatment. Contrast sensitivity in photopic, photopic with glare, scotopic, and scotopic with glare conditions all improved (p < 0.05), as did the modulation transfer function, Strehl ratio, and objective scattering index (p = 0.001, p = 0.008, and p = 0.001, respectively). Total corneal aberrations and the surface regularity index did not significantly differ before and after treatment; corneal high-order aberrations, standard deviation of corneal power, and the surface asymmetry index significantly improved after treatment (p = 0.045, p = 0.019, and p = 0.049, respectively). Changes in standard deviation of corneal power and in surface asymmetry index correlated with change in corneal fluorescein staining (p = 0.006 and p = 0.007, respectively).

Optical quality in patients with dry eye improved after treatment. The standard deviation of corneal power and surface asymmetry index could be indicators of treatment efficacy in dry eye.