#WhatIEatInADay: The effects of viewing food diary TikTok videos on young adults' body image and intent to diet.

The rise of short-form video content has prompted research into its impact on body image; however, little remains known regarding the effects of exposure to food-related content of this type. The present study aimed to fill this gap in the literature by conducting a between-subjects experiment (N = 316) examining the effects of exposure to low-calorie versus high-calorie "What I Eat in A Day" food diary TikTok videos on young adults' body appreciation, body dissatisfaction, and diet intentions. Additionally, this study sought to explore how social comparison and mood might affect participants' responses to these videos. Results indicate that social comparison mediated the relationship between video type (low- vs high- calorie) and positive mood, such that low-calorie videos increased upward social comparison and decreased positive mood, and high-calorie videos increased downward social comparison and increased positive mood. Positive direct effects of positive mood on body appreciation and diet intentions occurred, and a negative direct effect on body dissatisfaction was found. Additionally, positive mood mediated the path from social comparison to diet intentions. These findings highlight the importance of further research into the nuanced impacts of food diary social media content on young adults' body image and behaviors.

Clinical Comparison of High-resolution and Standard Refractions and Prescriptions.

SIGNIFICANCE: Recently, novel refraction technology allows subjective refractions to be performed with a higher-resolution. It is unclear, however, if these benefits are noticed and appreciated by the patient during the examination and after dispensing. PURPOSE: This study investigated benefits and drawbacks of high-resolution refraction technology over standard, specifically in terms of the refraction, glasses prescription, and participant's perceptions of the technology. METHODS: Sixty progressive-addition-lens wearers (aged 35 to 70 years) and 60 single-vision wearers (18 years or older) were randomized to a high-resolution refraction (Vision-R 800; Essilor Instruments, Dallas, TX; essilorinstrumentsusa.com ) and standard refraction in a 2-week crossover dispensing design. Refractive results were converted to M, J0, and J45 and analyzed using multivariate t tests. Bayesian estimation was used to analyze differences between refraction type and age group for subjective outcomes. RESULTS: Differences in refractive error between the two refractions were small, and none differed statistically ( P > .05) or clinically (e.g., <0.25 D) in either subgroup. Visual acuities at distance and near were better than 0.00 logMAR; none of the mean differences between the refractions reached statistical or clinical (e.g., <0.10 D) significance. Participants significantly preferred the high-resolution refraction for its quickness and efficiency, improved comfort, and less stress. Bayesian analysis indicated a 76% probability that participants had higher confidence in the high-resolution refraction, 93% probability that they would seek it out for their care, and 94% probability that they would recommend an optometrist using this technology. CONCLUSIONS: Refractive and acuity endpoints were similar with the high-resolution and standard refraction. Participants, however, perceived several key benefits of the high-resolution refraction and prescription for their care, the care of their friends/family, and the practice itself.

Accommodative Behavior, Hyperopic Defocus, and Retinal Image Quality in Children Viewing Electronic Displays.

SIGNIFICANCE: The prevalence of myopia and use of electronic displays by children has grown rapidly in recent years. We found that children viewing electronic displays, however, experience hyperopic defocus levels similar to those previously reported for other stimuli. PURPOSE: This study aimed to compare accommodative behavior of nonmyopic and myopic children viewing a computer screen or mobile phone. METHODS: Accommodative behavior was examined in 11 nonmyopic and 8 myopic children (11.32 ± 2.90 and 14.13 ± 2.30 years, respectively; P = .04; refractions, +0.51 ± 0.51 and -2.54 ± 1.29, respectively) using an open-field autorefractor (Grand Seiko) at target vergences from -0.25 to -5.00 D. Different size (scaled or nonscaled) and type (text or movie) stimuli were presented on an LCD monitor (distant) or an iPhone (near), with subjects viewing monocularly or binocularly in an illuminated or dark room. RESULTS: At the typical reading distances (20 and 33 cm), all 19 children exhibited some amount of accommodative lag. Stimulus type had little impact on accommodation. However, slightly but statistically significant lower slopes were observed (Bonferroni-corrected significance level of P ≤ .01) for low room lighting (0.96 vs. 0.91; t test, t = 3.88; P = .003), nonscaled targets (0.99 vs. 0.92; t test, t = 4.28; P = .001), and monocular viewing (0.99 vs. 0.90; t test, t = 4.0; P = .002) in the nonmyopic group only. When viewing nonscaled stimuli binocularly (natural viewing), the means and standard deviations of accommodative lags (averaged across room lights on and off, and text and movie) were generally larger for the nonmyopes at all distances and were largest at 33 cm (0.73 ± 0.18 D for the nonmyopes and 0.49 ± 0.23 for the myopes; t test, t = 2.62; P = .01). CONCLUSIONS: Generally small (≤0.50 D) amounts of hyperopic defocus are present in children binocularly viewing handheld electronic devices (nonmyopes slightly more than myopes). Modern electronic devices do not expose children to unusually high levels of hyperopic defocus.

Validation of a Clinical Aberrometer Using Pyramidal Wavefront Sensing.

SIGNIFICANCE: Measurement of ocular aberrations is a critical component of many optical corrections. PURPOSE: This study examines the accuracy and repeatability of a newly available high-resolution pyramidal wavefront sensor-based aberrometer (Osiris by Costruzione Strumenti Oftalmici, Firenze, Italy). METHODS: An engineered model eye and a dilated presbyopic eye were used to assess accuracy and repeatability of aberration measurements after systematic introduction of lower- and higher-order aberrations with calibrated trial lenses (sphere +10.00 to -10.00 D, and astigmatic -4.00 and -2.00 D with axis 180, 90, and 45°) and phase plates (-0.57 to 0.60 µm of Seidel spherical aberration defined over a 6-mm pupil diameter). Osiris aberration measurements were compared with those acquired on a previously calibrated COAS-HD aberrometer for foveal and peripheral optics both with and without multizone dual-focus contact lenses. The impact of simulated axial and lateral misalignment was evaluated. RESULTS: Root-mean-square errors for paraxial sphere (corneal plane), cylinder, and axis were, respectively, 0.07, 0.11 D, and 1.8° for the engineered model and 0.15, 0.26 D, and 2.7° for the presbyopic eye. Repeatability estimates (i.e., standard deviation of 10 repeat measures) for the model and presbyopic eyes were 0.026 and 0.039 D for spherical error. Root-mean-square errors of 0.01 and 0.02 µm, respectively, were observed for primary spherical aberration and horizontal coma (model eye). Foveal and peripheral measures of higher- and lower-order aberrations measured with the Osiris closely matched parallel data collected with the COAS-HD aberrometer both with and without dual-focus zonal bifocal contact lenses. Operator errors of focus and alignment introduced changes of 0.018 and 0.02 D/mm in sphere estimates. CONCLUSIONS: The newly available clinical pyramidal aberrometer provided accurate and repeatable measures of lower- and higher-order aberrations, even in the challenging but clinically important cases of peripheral retina and multifocal optics.

Calibration of the PlusOptix PowerRef 3 with change in viewing distance, adult age and refractive error.

PURPOSE: The PowerRef 3 is frequently used in studying the near triad of accommodation, vergence and pupil responses in normal and clinical populations. Within a range, the defocus measurement of the PowerRef 3 is linearly related to the eye's defocus. While the default factory-calibrated slope of this relation (calibration factor) is 1, it has been shown that the slope can vary across individuals. Here, we addressed the impact of changes in viewing distance, age and defocus of the eye on the calibration factor. METHODS: We manipulated viewing distance (40 cm, 1 m and 6 m) and recruited participants with a range of accommodative capabilities: participants in their 20s, 40s and over 60 years old. To test whether any effect was larger than the range of measurement reliability of the instrument, we collected data for each condition four times: two in the same session, another on the same day, and one on a different day. RESULTS: The results demonstrated that viewing distance did not affect the calibration factor over the linear range, regardless of age or uncorrected refractive error. The largest proportion of the variance was explained by between-subject differences. CONCLUSIONS: Calibration data for the PowerRef 3 were not sensitive to changes in viewing distance. Nevertheless, our results re-emphasise the relevance of calibration for studies of individual participants.