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The progression of myopia in young adults due to inadequate accommodation is currently one of the global research challenges. Studies have demonstrated that multifocal contact lenses have a different effect on accommodative response. The aim of this study was to assess the accommodative lag using various design multifocal contact lenses at different working distances. The study was conducted on 10 emmetropic subjects aged 22â28 years. An open-field autorefractor PowerRef 3 was used to assess the response of eye accommodation to stimuli placed at a distance of 25 cm and 40 cm for subjects wearing monofocal and multifocal contact lenses. To determine the effectiveness of contact lens design for accommodative lag compensation, the results of the accommodative lag with and without contact lenses were compared. The measured accommodative lag for stimuli at 40 cm was 1.05 ± 0.11 D and for stimuli at 25 cm 1.53 ± 0.11 D. Regarding the effect of multifocal contact lenses, it was determined that the near vision power zone in the centre of the lens reduces the accommodative lag, while the respective distance vision power zone does not produce a statistically significant change. The near power zone in the centre of the multifocal contact lens effectively affects the accommodative lag by reducing accommodation inaccuracy as effectively as spherical contact lenses with positive power. The addition design for multifocal lenses (Med or Hi) does not significantly affect the accommodative lag. The results of centre-distance multifocal contact lenses depend on the strength of the addition used.

The classical treatment option for amblyopia in Latvia is occlusions of the non-amblyopic eye. The newest methods involve specialized computer games that involve both eyes in visual processing during the treatment as well as stimulate binocularity. To assess the efficiency of specialized computer games in the treatment of amblyopia in school-age children in Latvia, 237 children (7â18 years old) participated in the experiment, of whom only 22 completed it: 11 participants had occlusion therapy, 11 participants played the specialized dichoptic computer game Tetris®. The visual acuity of the amblyopic eye as well as stereopsis were evaluated at near and far distances before the treatment, 2 months and 4 months after the beginning of the treatment. The results show statistically significant improvement in visual acuity in both treatment groups after four months of therapy. The extent of improvement is similar in both groups. Specialized computer games for amblyopia treatment may be recommended to patients from an age when they are able to use a computer along with a keyboard and computer mouse, who want to improve their visual acuity in the amblyopic eye but are not willing to use occlusions. The only requirement for using specialized games is that the patients need to have binocular single vision. In conclusion, the use of specialized computer games is an alternative type of amblyopia treatment compared to occlusion therapy.

Sometimes yellow-tinted lenses are recommended to help improve visual quality. As yellow lenses filter blue light, it is believed that their use could decrease the intensity of scattered light in the eye (retinal straylight). However, the results of some studies have contradicted this assumption (Van Os et al. 2017). Currently various nontinted blue-light-blocking lenses are used to protect the eyes from short-wavelength light. The objective of this study was to determine whether blue-light-blocking lenses affect the levels of retinal straylight in the eye. A straylight meter (C-Quant, Oculus) was used for retinal straylight measurements. The measurements were performed under four different conditions: 1. without a spectacle lens in front of the eye, 2. with a plano lens without an antireflective (AR) coating, 3. with a lens with a blue-light-blocking coating, and 4. with a yellow-tinted lens without an AR coating. The study involved 37 subjects with a mean age of 22 ± 1.3 (SD) years. No significant differences in straylight parameters (s) (p > 0.05) were observed for measurements obtained without a lens in front of the eye (log[s] = 0.90 ± 0.02 [SE]), with the uncoated lens (log[s] = 0.92 ± 0.02) and with the lens with a blue-light-filtering coating (log[s] = 0.92 ± 0.02). Retinal straylight was significantly increased with the use of a yellow-tinted lens (log[s] = 0.96 ± 0.02) compared with no lens (p < 0.001). Neither yellow-tinted lenses nor nontinted blue-light-blocking lenses reduce the levels of retinal straylight in the eye.

Discrepancies between depth cues (accommodation and vergence) is one of the major issues caused in a stereoscopic augmented reality at close viewing distances. It adversely affects not only user comfort but also spatial judgements. Images with consonant cues at different distances have become available due to the implementation of multifocal architecture in the head-mounted displays, although its effect on spatial perception has remained unknown. In this psychophysical study, we investigated the effects of consonant and conflicting depth cues on perceptual distance matching in the stereoscopic environment of augmented reality using a head-mounted display that was driven in two modes: multifocal mode and single-focal plane mode. The participants matched the distance of a real object with the images projected at three viewing distances (45 cm, 65 cm, and 115 cm). As a result, no significant differences in the accuracy of spatial perception were shown depending on the consistency of cues. However, the perceptual tasks were completed faster when the depth cues were consonant. Overall, the results of our experiment show that consonant depth cues facilitate faster judgements on spatial relations between real objects and images projected in augmented reality, which can be achieved when images are displayed using multiple depth planes in the head-mounted display. Further technological advancements might be required to improve the accuracy of spatial judgements in augmented reality.

Nanosized spherical ZrO2 (Y2O3)-Al2O3 particulate composites with average particle size in the range of 30-40 nm have been prepared by evaporation of coarse grained oxides in an inductively coupled plasma. The powders contain m-, t-ZrO2 and θ-, δ- Al2O3 phases. The presence of Al2O3 reduces the crystallite size of ZrO2 and increases the content of the t-ZrO2 phase and prevents phase transition of ZrO2 during additional calcinations. The surface characteristics of ZrO2-Al2O3 particles testify that zirconia particles are covered by alumina.