Impact of Defocus and High-Order Aberrations on Light Disturbance Measurements

Abstract EN

Purpose.

To evaluate the impact of different levels of positive and negative defocus on light disturbance (LD) measures and to understand how high-order aberrations (HOAs) and topographic quality parameters may influence the perception of photic phenomena.

Methods.

Thirty young healthy subjects (21 females and 9 males) attended this cross-sectional study.

LD was evaluated with the light distortion analyzer (LDA) in natural accommodative and cycloplegic conditions with positive and negative induced defocus of 1.00D.

HOAs were taken for a natural mesopic (without cycloplegia) and for fixed 5 mm (with cycloplegia) pupil size.

The impact of corneal morphological parameters (SAI, SRI, and Q-value) in LD was also investigated.

Results.

Positive and negative induced defocus of 1.00D significantly increased the size of LD (p<0.010, Wilcoxon signed rank test) but not its irregularity index.

Spherical-like HOAs were associated with the size of LD, while coma-like and total-like HOAs were associated with LD irregularity.

Our results showed that SRI was significantly correlated with the size of the disturbance area (r=0.519, p=0.003, Spearman correlation) and SAI with both size (r=0.502, p=0.005, Spearman correlation) and irregularity (r=0.371, p=0.044, Spearman correlation).

However, no correlation between the Q-value and LD parameters was found.

Conclusions.

The uncorrected positive and negative refractive errors might increase the size of the LD, such as the spherical-like HOAs, SAI, and SRI, instead of asphericity.

Coma-like and total-like HOAs and SAI may influence the perception of irregularities in the LD shape.

These results might have an impact on postrefractive surgery visual performance that should be investigated.