Search Results (9)

Virtual reality (VR) can challenge the visual system, leading to temporary oculomotor changes, though the degree of change varies among individuals. While the vergence and accommodation system plays a crucial role in VR perception, it remains unclear whether individuals whose visual functions fall outside clinical norms experience larger changes. Thus, our study aimed to investigate whether changes in vergence and accommodation responses following VR gameplay differ between individuals with and without non-strabismic binocular and accommodative disorders. To assess this, both subjective and objective measurements were conducted before and after 20 min of playing Beat Saber. Results revealed significant alterations across both subjective measurements—near point of convergence and near point of accommodation—and objective measurements, including eye refraction, accommodation lag, and accommodative microfluctuations at far. Moreover, individuals with non-strabismic binocular and accommodative disorders exhibited larger accommodative microfluctuations at far compared to the control group. Overall, these findings indicate that considering individual differences in vergence and accommodation responses is important when evaluating the impact of VR on the visual system and can be helpful in the design and use of VR systems, particularly for individuals with binocular and accommodative disorders. Full article

The diagnostic value of the computer accommodation method remains insufficiently studied. Accommodative and refractive error is a common problem, accounting for 23% of the world’s population. The aim of the study was to investigate the objective parameters of accommodative insufficiency in young people with and without myopia. A cross-sectional study was carried out using a random sample of 116 of university students at the age of 21–23 years. Normal ranges for accommodation parameters in non-myopic participants were defined by 10th and 90th percentile values. The normal ranges were from −0.17 to −0.38 conventional units (c.u.) for accommodative response coefficient (ARC), from 0.08 to 0.41 c.u. for deviation of ARC (σARC), from 0.0 to 0.43 c.u. for accommodogram growth coefficient (AGC), from 54.26 to 58.55 microfluctuations per minute (mcf/min) for coefficient of microfluctuations (CMF), and from 2.58 to 5.26 c.u. for deviation of CMF (σCMF). Signs of computer visual syndrome were observed in 40.9% of non-myopic participants, eye strain in 11.9%, accommodation cramp in 4.5%, and absence or little accommodative response in 3.6%. Therefore, computer accommodation assessment allowed the detection of young people with an increased risk of myopia among those without this ophthalmic pathology. Full article

Spasm of near reflex (SNR) involves intermittent spasm of one or more of the three near reflex components. Psychiatric disorders are one cause of SNR. We describe a patient with SNR diagnosed with autism spectrum disorder (ASD). A 36-year-old male with esotropia since childhood was referred due to headache and dizziness. The alternate prism cover test showed 30 prism diopters at both near and distant fixation. Four months after his first visit, he was diagnosed with ASD. Twenty-nine months after his first visit, he underwent strabismus surgery to treat concomitant esotropia. Postoperatively, the angle of strabismus improved but remained variable. Because the angle of strabismus varied, we suspected SNR; the diagnosis was performed after evaluating the patient’s microfluctuations in accommodation with Speedy-K. However, it was difficult to distinguish convergence spasm from concomitant esotropia in this patient because he has had a history of esotropia since childhood. In a patient with concomitant esotropia, if the symptoms are not exclusively due to strabismus, SNR should be suspected. Although the relationship between SNR and the pathology of ASD is unknown, it is possible that patients with ASD are more likely to develop SNR. Full article

Background: We aimed to evaluate the existence of accommodative microfluctuations in eyes after cataract surgery. Methods: This retrospective observational cohort study included 1160 eyes of 713 patients (mean age: 72.5 ± 8.3 years) who underwent phacoemulsification, intraocular lens insertion, and an evaluation of accommodative microfluctuations with an autorefractometer. Patients with posterior segment disorders resulting in visual acuity impairment and those with unavailable medical information were excluded. High-frequency components (HFCs), between 1.0–2.3 Hz, based on fast Fourier transform analysis of the accommodative microfluctuation data were examined at postoperative 2–3 (2 M) and 6 months (6 M). The relationships between the HFCs and patient age, manifest refraction, and axial length were analyzed. Results: Increased HFC values (>65) were observed at a constant rate after cataract surgery, with prevalence rates of 33.4% at 2 M and 34.7% at 6 M. Postoperatively, at 2 M, increased HFC values were significantly more common for eyes with axial length ≥26 mm than for those with axial length <26 mm (p = 0.0056). However, they were not significantly correlated to age or postoperative manifest refraction. Conclusions: At 2 M postoperatively, increased HFC values presented more frequently in eyes with a greater axial length; hence, the precise detection and understanding of postoperative accommodative spasms in high myopia patients is important. Full article

Near work has been considered to be a potential risk factor for the onset of myopia, but with inadequate evidence. Chinese adolescents use digital devices for near work, such as study and entertainment purposes, especially during the COVID-19 pandemic. In this study, we investigated the influence of prolonged periods of near work on accommodative response, accommodative microfluctuations (AMFs), and pupil diameter between juvenile subjects of myopia and emmetropia. Sixty juveniles (30 myopes and 30 emmetropes) were recruited for the study. Participants were instructed to play a video game on a tablet PC at a distance of 33.3 cm for 40 min. Accommodative response and pupil diameter were measured with an open-field infrared refractometer in High-speed mode. Parameters of the subjects were measured once every 10 min, and analyzed by one-way repeated measure ANOVA for variation tendency. There were no significant differences between emmetropia and myopia groups with respect to age and sex (p > 0.05). The low-frequency component (LFC) of myopia gradually increased with time, reached a peak at 30 min, and then declined (p = 0.043). The high-frequency component (HFC) of myopia also reached a peak at 30 min (p = 0.036). Nevertheless, there was no significant difference in the LFC (p = 0.171) or HFC (p = 0.278) of the emmetropia group at each time point. There was no significant difference in the mean and standard deviation of the accommodative response and pupil diameter both in emmetropic and myopic juveniles. Compared with juvenile emmetropes, myopes exhibit an unstable tendency in their accommodation system for prolonged near work at a certain time point. Accommodative microfluctuations may be a sensitive, objective indicator of fatigue under sustained near work in juvenile myopes. Full article

Purposes: This study discussed the accommodative response and pupil size of myopic adults using a double-mirror system (DMS). The viewing distance could be extended to 2.285 m by using a DMS, which resulted in a reduction and increase in the accommodative response and pupil size, respectively. By using a DMS, the reduction of the accommodative response could improve eye fatigue with near work. Method: Sixty subjects aged between 18 and 22 years old were recruited in this study, and the average age was 20.67 ± 1.09. There were two main steps in the experimental process. In the first step, we examined the subjects’ refraction state and visual function, and then fitted disposable contact lenses with a corresponding refractive error. In the second step, the subjects gazed at an object from a viewing distance of 0.4 m and at a virtual image through a DMS, respectively, and the accommodative response and pupil size were measured using an open field autorefractor. Results: When the subjects gazed at the object from a distance of 0.4 m, or gazed at the virtual image through a DMS, the mean value of the accommodative response was 1.74 ± 0.43 or 0.16 ± 0.47 D, and the pupil size was 3.98 ± 0.06 mm or 4.18 ± 0.58 mm, respectively. With an increase in the viewing distance from 0.4 m to 2.285 m, the accommodative response and pupil size were significantly reduced about 1.58 D and enlarged about 0.2 mm, respectively. For three asterisk targets of different sizes (1 cm × 1 cm, 2 cm × 2 cm, and 3 cm × 3 cm), the mean accommodative response and pupil size through the DMS was 0.19 ± 0.16, 0.27 ± 0.24, 0.26 ± 0.19 D; and 4.20 ± 1.02, 3.94 ± 0.73, 4.21 ± 0.57 mm, respectively. The changes of the accommodative response and pupil size were not significant with the size of the targets (p > 0.05). In the low or high myopia group, the accommodative response of 0.4 m and 2.285 m was 1.68 ± 0.42 D and 0.21 ± 0.48 D; and 1.88 ± 0.25 D and 0.05 ± 0.40 D, respectively. The accommodative response was significantly reduced by 1.47 D and 1.83 D for these two groups. The accommodative microfluctuations (AMFs) were stable when a DMS was used; on the contrary, the AMFs were unstable at a viewing distance of 0.4 m. Conclusions: In this study, the imaging through a DMS extended the viewing distance and enlarged the image, and resulted in a reduction in the accommodative response and an increase in the pupil size. For the low myopia group and the high myopia group, the accommodative response and pupil size were statistically significantly different before and after the use of the DMS. The reduction of the accommodative response could be applied for the improvement of asthenopia. Full article

A 12-week-long randomized, double-blind, placebo-controlled, parallel-group comparison trial was conducted to determine the effects of long-term standardized bilberry extract (SBE) intake on tonic accommodation of ciliary muscle caused by visual display terminal (VDT) tasks. This study was compliant with the accordance with CONSORT 2010 statement. A total of 109 healthy adult men and women aged 20–60 years were recruited and randomized into SBE and placebo groups. The subjects in the SBE and placebo groups were administered 240 mg of SBE and placebo, respectively, once daily for 12 weeks. Tests were performed before and after VDT tasks at week 0, 4, 8, and 12; high-frequency component (HFC)-1 value was the evaluation outcome. Results showed that post-load HFC-1 values at weeks 8 and 12 were significantly improved in the SBE group than in the placebo group (p = 0.014 and 0.017, respectively). This study shows that oral consumption of 240 mg SBE extract for 12 weeks relieves the tonic accommodation of the ciliary muscle caused by VDT tasks and near-vision tasks. Full article

Volumetric display shows promising implications for healthcare related applications as an innovative technology that creates real three-dimensional (3D) image by illuminating points in three-dimensional space to generate volumetric images without image separation. We used eccentric photorefractometry to objectively study ocular performance in a practical environment by evaluating near work-induced refraction shift, accommodative microfluctuations, and pupil size for 38 young adults after viewing anaglyph, and volumetric 3D content for prolonged time. The results of our study demonstrate that participants who performed relative depth estimation task on volumetric 3D content were less likely to experience task-induced myopic refraction shift. For both 3D content types, we observed pupil constriction, that is possibly related to visual fatigue. For anaglyph 3D pupil constriction, onset was observed significantly sooner, compared to volumetric 3D. Overall, sustained work with 3D content, and small disparities or the fully eliminated possibility of accommodation-vergence conflict, not only minimizes near work-induced myopic shift, but also provide beneficial accommodation relaxation that was demonstrated in this study as hypermetropic shift for nearly half of participants. Full article

Previous studies have shown cognition to have an influence on accommodation. Temporal variation in the accommodative response occurs during the fixation on a stationary target. This constantly shifting response has been called accommodative micro-fluctuations (AMFs). The aim of this study is to determine the effects of increasing task cognitive demand on the ocular accommodation response. AMFs for 12 myopes and 12 emmetropes were measured under three conditions of varying cognitive demand and comprising reading of numbers (Num), simple arithmetic (SA), and complex arithmetic (CA). Fast Fourier transforms were used to analyze the different frequency band components of the AMFs. Other aspects of AMFs including root mean square accommodation values and chaos analysis was applied. A repeated measures ANOVA revealed a significant main effect of cognition in the mean power of the high frequency component (HFC) (F_2,44 = 10.03, p < 0.005). Pairwise analyses revealed that these differences exist between SA and CA tasks (p < 0.005) and the Num and CA (p < 0.005) tasks with the HFC power being the highest for the CA condition. It appears that the difficulty of a task does affect active accommodation but to a lesser extent than other factors affecting accommodation. Full article