Light distortion and spherical aberration for the accommodating and nonaccommodating eye

Abstract

To evaluate how different amounts of induced spherical aberration (SA) affect the light distortion (LD) phenomena, tests were performed using an experimental device to measure the distortion (haloes, glare, and so on) of a point source. To simulate the effect of SA, eight different phase plates between +0.300 and −0.300 μm of SA for a 5-mm aperture were used in a random and double-masked experimental design. Measurements were performed at a distance of 2 m in a darkened room in 10 eyes of five subjects with a mean age of 26.4±6.1 years and a mean refractive error of −0.50±0.70 D. Data were obtained with natural pupil and after pupil dilatation. The measurements with this experimental system showed a significant increase in all distortion parameters with cycloplegia for the phase plates with the higher positive SA (+0.300 and +0.150 μm). The disturbance index increased from 14.86±6.12% to 57.98±36.20% (p<0.05) with the +0.300 μm plate. The same effect was observed through at a much lower rate when the eye could accommodate. Plates inducing negative SA did not change the LD compared to the control condition without induction of SA or even decreased the effect of distortion. Pupillary dilation and cyclopegia led to a significant increase in the size of the LD when increasing values of SA were induced. Accommodation and pupillary constriction are capable of compensating the degradation of the optical quality induced.

Light disturbance with multifocal contact lens and monovision for presbyopia

“…On one level, this may explain the differences observed in LD between dominant (center-distance design) and non-dominant (center-near design). However, in contrast to the results of Macedo-de-Araujo et al [29], it was found that the increase in LD was greater with the center-near design (more negative SA) compared to center-distance design. This may be due to the difference for SA induced by multifocal design compared to those experimentally induced in previous studies.…”

“…Macedo-de-Araújo et al 29 reported that the induction of +0.15 μm spherical aberration (SA) leads to an increase between 10 and 20% in light disturbance index (LDI). Considering that the mean induced SA by multifocal CL are in that order of magnitude, the sample size required was 18 subjects, to warrant an 80% power (type II error risk of 20%) and to detect 10% differences in LDI between follow-up visits, for a statistical significance level of p = 0.05 (type I error risk of 5%).…”

Corneal Aberrations, Contrast Sensitivity, and Light Distortion in Orthokeratology Patients: 1-Year Results

“…We cannot ensure that the LD parameter reflects specifically the haloes, ghost images, starburst, and glare reported subjectively by the patient. However, we have reported in a recent study that the system is sensitive to the photic phenomena induced when we artificially incorporate different amounts and sign of HOA [18]. Although we cannot quantify each one of the photic phenomena, we consider that such effects are well reflected in the short-term measurements in this study and that adaptation takes place to reduce the size of the LD overtime in the middle [14] and longer term (present study), in agreement with transient subjective complaints expressed by the patient in the clinical setting [13].…”

“…It consists of an array of 240 1 mm wide LEDs distributed radially at 15° intervals over 160 mm, with a linear separation of 10 mm around a central 5 mm white LED that acts as glare source, as previously described [17, 18, 20]. The system is controlled by a custom-made software that interfaces with the patient to detect the peripheral stimuli seen and discriminate them from those hidden by the central glare source.…”

“…We use a physical display to present the stimuli as this allows us to have a wider dynamic range of luminance from the main glare source and the detection peripheral stimuli [20] and this instrument has been shown to be consistent with [17] and sensitive to changes in higher-order aberrations (HOA) artificially induced [18]. …”