Screen-time reduction may reverse potential screen-induced foveal dysfunction in Computer Vision Syndrome

Electronic devices or screens might be responsible for the emergence of unexplained recent era of deterioration of visual functions and performances with underlying mechanisms not fully understood. Reduction of the visual sensitivity in the dark with smartphone use has been reported. Hand-held devices are responsible for reduction of fusional convergence and recession of near point of convergence. Linearly polarized smartphones are responsible for asthenopia and reduced confusion flicker frequency. Smartphone has adverse effects on binocular vision by decreasing the binocular accommodative facility. Electronic devices might be responsible for accommodative disorders and convergence insufficiency in pediatric users.

Iqbal et al conducted a study to document the mfERG changes foveal responses in cases with screen-induced foveal dysfunction before and after strict reduction of the screen-time to ≤1 screen-hour daily as our primary outcomes. Meanwhile, the secondary outcome was discovering the associated changes in visual performances.

This prospective multicenter cohort comparative study included 49 eyes of 49 medical students divided into two groups. Group A (control group) included 25 eyes with no CVS diagnosis while group B (CVS group) included 24 eyes with CVS diagnosis. All students responded to the valid and reliable CVS-Form 3 (CVS-F3) questionnaire and underwent complete ophthalmic and mfERG examinations twice at the time recruitment in the study and four weeks after strict reduction of the daily screen-hours to ≤1 screen-hour daily to document associated foveal responses.

Authors documented statistically significant reduction in foveal responses in CVS versus control groups in mean mfERG Rings 1, 2, and 5 with Quadrants 1, 2, and 4 (P=< 0.0001, 0.0001, 0.0003, 0.001, 0.002, and 0.006, respectively). Following the screen-time reduction, the second mfERG examination revealed significant post-reduction improvements in foveal responses in CVS group particularly in mean mfERG Rings 1, 2, 3, and 5 with Quadrants 1 and 4 (P=< 0.0001,< 0.0001, 0.0005, 0.02,< 0.0001, and 0.04, respectively).

This study documented the existence of the screen-induced foveal dysfunction in CVS patients using mfERG examinations. Additionally, they exhibited statistically significant post-reduction remarkable improvements in almost all mfERG Rings and Quadrants in the CVS group. Therefore, authors suggest that the screen-induced foveal dysfunction might be reversible if the total screen-time reduced to ≤1 screen-hour daily. These outcomes might signify that if a CVS patient, with positive mfERG findings, managed to completely stop using screens for four weeks, his/her mfERG findings mostly will be normal.

The screen-induced foveal dysfunction outcomes might be due to the dysfunction in the retinal bipolar cells in the macular cones. These bipolar cells are mainly the basic retinal interneurons responsible for the fast and direct visual signals pathways from the cones to the ganglion cells. Moreover, authors think that the mfERG changes emerged from this screen-induced foveal dysfunction might originally have been elicited by the direct light exposure from the screens caused by numerous factors, such as the cone adaptation or the spectral output of the screens, which varies from device to device, and among subjects and might be related to the potential electrode/focusing effects. They posit that these interpretations might explain why the screen-induced foveal dysfunction outcomes could be reversible. Meanwhile, the longer-wavelength light high levels are more effective in adaptation of the M and L cones than the shorter-wavelength light exposure.

“In conclusion, the current study outcomes proved the existence of screen-induced foveal dysfunction as mfERG sign of CVS. We think that the mfERG changes elicited by the screen-induced foveal dysfunction are reversible with strict reduction of screen-time to ≤1 screen-hour daily resulting in significant post-reduction improvements in the foveal responses. Additionally, the great significant post-reduction improvements in both mean UDVA and CDVA that associated the foveal responses improvements support our conclusion of the reversibility of the adverse effects of screeninduced foveal dysfunction with strict screen-time reduction. Therefore, we posit that the complete stoppage of using screens, if possible, is capable of regaining the original foveal functions and visual performances. Furthermore, future studies with larger sample size are recommended.”

Source: Iqbal et al ;Clinical Ophthalmology 2023:17

https://doi.org/10.2147/OPTH.S399044