Binocular dynamics of accommodation, convergence, and pupil size in myopes

Application of a New Device for Vision Relaxation in Computer Users

This study aims to explore the potential of a novel EYE ROLL device designed to facilitate guided vision relaxation exercises in an open space. A prospective study was performed on 89 participants who perform screenwork for at least four hours daily. All participants were randomly divided into three groups: a Control group with no exercising, a Manual group undertook manual vision relax ation exercises, and an Eyeroll group engaged in EYE ROLL device-assisted vision relaxation exercises. Each participant underwent three evaluations (an initial baseline assessment, a 4-week follow-up, and an 8-week follow-up) with four assessment tools: a comprehensive vision examination, an in-depth questionnaire, saccadic eye movement recordings, and objective accommodation measurements. There was a statistically significant decrease (35% and above) in complaint scores at the 4-week follow-up in both training groups. Although statistically insignificant, complaints continued to decrease after an 8-week period. No significant changes were observed in clinical or objective accommodative parameters. Some variation of visual functions was observed in all groups due to repeated measures. Vision relaxation exercises combined with proper vision ergonomics and working habits can reduce asthenopic complaints. The EYE ROLL device presents a promising tool for integrating these exercises into the working environment.

Contrast sensitivity is resilient to induced fast periodic defocus oscillations

This study investigates the potential effects of periodic defocus oscillations on contrast sensitivity. Sinusoidal fluctuations at 5, 15, and 25 Hz, with defocus peak-to-valley values ranging from 0.15 to 3 D, were induced by means of a focus-tunable lens after calibrating its dynamic behavior. Monocular contrast sensitivity was measured on five young emmetropic subjects. The experimental data shows that contrast sensitivity loss due to defocus fluctuations is low for a wide range of frequencies and amplitudes. Only for the more severe case studied (25 Hz, ± 1.5 D) contrast threshold showed a clear increase in most subjects. Qualitative comparison of the empirical data with a simulation of modulation loss due to time integration of defocused retinal point spread functions, suggests a short integration time by the eye for defocus blur, around or even below a hundredth of a second.

Change in three-dimensional choroidal vessel network after AR device assisted 1-hour visual task in 2D/3D mode in young healthy subjects

PURPOSE

The purpose of the study was to investigate the changes of choroidal blood perfusion in different layers and quadrants and its possible related factors after 1 h visual task by augmented reality (AR) device in two-dimensional (2D) and three-dimensional (3D) mode, respectively.

METHODS

Thirty healthy subjects aged 22-37 years watched the same video source in 2D and 3D mode separately using AR glasses for 1 h with a one-week interval. Swept-source optical coherence tomography angiography (SS-OCTA) was performed before and immediately after watching to acquire choroidal thickness (ChT), three-dimensional choroidal vascularity index (CVI) of large- and middle-sized choroidal vessels and choriocapillaris flow voids (FV%) at macular and peripapillary area. Near point of accommodation (NPA) and accommodative facility (AF) were examined to evaluate the accommodative ability. Pupil diameters by infrared-automated pupillometer under scotopic, mesopic and photopic condition were also obtained.

RESULTS

Compared with pre-visual task, the subfoveal CVI decreased from 0.406 ± 0.097 to 0.360 ± 0.102 after 2D watching (p < 0.001) and to 0.368 ± 0.102 after 3D watching (p = 0.002). Pupil sizes under different illuminance conditions became smaller after both 2D and 3D watching (all p < 0.001). AF increased after both 2D and 3D watching (both p < 0.05). NPA receded in post-3D watching (p = 0.017) while a not significant tendency was observed in post-2D.

CONCLUSION

A reduction in subfoveal choroidal blood flow accompanied with pupil constriction was observed immediately after 1 h visual task using AR glasses in 2D and 3D mode. Accommodative facility improved after 2D and 3D watching with AR glasses, whereas decrease in the maximum accommodation power was only found in 3D mode.

Using a video-based eye tracker to analyse the binocular near-reflex dynamics response

PURPOSE

This study presents a novel video-based eye-tracking system for analysing the dynamics of the binocular near-reflex response. The system enables the simultaneous measurement of convergence, divergence and pupillary size during accommodation and disaccommodation to aid the comprehensive understanding of the three-component near-reflex.

METHODS

A high-speed (90 Hz) video-based eye tracker was used to capture changes in eye gaze and pupil radius in 15 participants in response to altering stimulus conditions. An offline analysis involved separating the gaze vector components and pupil radius, which were fitted to a hyperbolic tangent function to characterise the dynamics of the near-reflex process.

RESULTS

Significant differences in the temporal parameters of the pupil radius were observed between the near-to-far and far-to-near vision changes, with faster miosis compared with mydriasis. Additionally, differences in response times were found between gaze angle components, with longer convergence times compared to changes in the vertical direction (saccades). The steady-state values of the gaze components and pupil radius were in line with theoretical expectations and previous reports.

CONCLUSIONS

The proposed system provides a non-invasive, portable and cost-effective method for evaluating near-reflex dynamics under natural viewing conditions using a video-based eye tracker. The sampling rate ensures the accurate assessment of vergence eye movements and pupillary dynamics. By simultaneously measuring eye convergence, divergence and pupil size, the system offers a more comprehensive assessment of the near-reflex response. This makes it a valuable tool for clinical diagnosis, research studies and investigating the effects of near work on the visual system.

Comparison of higher-order aberrations between implantable collamer lens V4c implantation and simulated spectacle correction in patients with high myopia

PURPOSE

To investigate the differences in higher-order aberrations between non-toric or toric implantable collamer lens (ICL or TICL) V4c implantation and simulated spectacle correction.

METHODS

Patients with high myopia who underwent ICL/TICL V4c implantation were enrolled. The "total no defocus" pattern of iTrace aberrometry to simulate the condition of spectacle correction was measured before ICL/TICL implantation, and higher-order aberrations in this condition were compared to those 3 months after surgery. Related factors with changes in coma were comprehensively analyzed.

RESULTS

A total of 89 right eyes of 89 patients were included. Compared to simulated spectacle correction, total-eye coma (P<0.0001 ICL, P<0.0001 TICL) and internal coma (P<0.0001 ICL, P<0.001 TICL) decreased in the ICL- and TICL-treated groups after surgery. Total-eye secondary astigmatism (P<0.0001 ICL, P=0.007 TICL) and internal secondary astigmatism (P<0.0001 ICL, P=0.009 TICL) were also decreased in both groups postoperatively. Spherical error showed positive correlations with variation in total-eye coma (r=0.37, P=0.004 ICL; r=0.56, P=0.001 TICL) and internal coma (r=0.30, P=0.02 ICL and r=0.45, P=0.01 TICL). Axial length revealed negative correlations with changes in total-eye coma (r=-0.45, P<0.001 ICL; r=-0.39, P=0.03 TICL) and internal coma (r=-0.28, P=0.03 ICL and r=-0.42, P=0.02 TICL).

CONCLUSIONS

Both ICL- and TICL-treated groups demonstrated a decrease in coma and secondary astigmatism after 3 months, postoperatively. ICL/TICL may confer a compensatory effect on coma aberration and secondary astigmatism. Patients with a higher myopia achieved a greater improvement in coma and may benefit more from ICL/TICL implantation than from spectacle correction implantation than from spectacle correction.

Kinetic pupillary size using Pentacam in myopia

Purpose

To compare if the kinetic pupillary changes differs between high myopia (HM) and low/moderate myopia by Pentacam.

Setting

Chinese People's Liberation Army (PLA) General Hospital, Beijing, China.

Design

Comparative study.

Methods

In this cross-sectional retrospective study, 44 eyes of 44 patients were recruited in the Refractive Surgery Center of Chinese PLA General Hospital. Eyes were divided into two groups according to the refractive error: low/moderate myopia (22 eyes; -2.99 ± 1.09 D) and HM (22 eyes, -12.93 ± 3.44 D). At the beginning of the experiment, we made trials of scanning one false pupil by Pentacam. All patients underwent the Pentacam examination three times. Pupillary diameters (PD) during the scan process and other parameters were measured using the Pentacam. Coefficient variations of PD (CV) during the different scanning periods were analyzed comparatively between the two groups.

Results

Pentacam once time output 25 Scheimpflug images, with 13 ones during the period from 1st to 1.5th s and 12 ones during the period from 2.5th to 3rd s after the scanning onset. For the spatial order on all the 25 meridians, 13 Scheimpflug images came out when the Pentacam rotated from 60° to 153°meridians and the remaining 12 Scheimpflug images from 161° to 245° meridians. Among pupillary parameters, no statistical significance existed in PD25, PD13, and PD12 (pupil diameter's mean from all, former 13 and remaining 12 of 25 Scheimpflug images, respectively) (P > 0.05) between the two groups. However, there were statistically significant differences in CV25 and CV13 (coefficient variation of the pupil diameters from all and former 13 of 25 images, respectively) (P < 0.001), with no statistical significance in CV12 (coefficient variation of the pupil diameters from remaining 12 of 25 images) between both groups.

Conclusion

Twenty-five Scheimpflug images on Pentacam had the temporal and the spatial orders. CV in eyes with HM was lower than that in eyes with low/moderate myopia in a certain period of the Pentacam scan. Kinetic pupillary size in HM changed more slowly than that in low/moderate myopia during some scanning period analogous to the phasic response of the pupil reflex.