Authors : Bachan Chaudhary; Bishal Bhujel; A. P. Nishad Begum

Volume/Issue : Volume 11 - 2026, Issue 1 - January

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DOI : https://doi.org/10.38124/ijisrt/26jan384

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Abstract :  Background: The increasing use of laptops and other digital devices has led to visual discomfort and fatigue due to prolonged near work, involving accommodation and vergence stress. Blue light from screens is believed to contribute to digital eye strain, and blue light filtering lenses are widely marketed to improve visual comfort.  Objective: To assess and compare the acute effect of blue light filters on vergence (NPC, VF, AC/A), accomodation parameters (NPA, AF) and visual comfort after using laptop for 1 hour.  Methodology: All participant underwent a preliminary workup that included distance and near visual acuity at 6 meters and 40 cm, respectively, which were measured using a logarithmic of the minimum angle of resolution (LogMAR) chart.Individuals with distance visual acuity equal to or better than 6/6 and near vision N6 were included in the study. Subjects with a history of ocular or systemic disease, spectacle, and/or contact lens wearers or those using any BL protection products were excluded. After this,for baseline the NPA is measured both monocularly (direct) and binocularly (indirect).Then AF is measured using ±2.00D flippers. Also NPC is measured using linear target and VF using flippers with 12D BO & 3D BI Prism. Here AC/A ratio is calculated using heterophoric method. The brightness is adjusted using luxmeter with no any night mode on. After baseline data, now participant is given a laptop for 1 hour to watch video same procedure conducted under two condition; with and without blue light filters,with two trails separated by a period of 24 hours.On first day,no filter was used ,while blue light filter was used on next day.Along with this 16 questionnaire developed by Aaras et. al, is also asked for the participant to know their visual comfort(graded from 0-2).  Result: Across 48 young adults (23 males, 25 females), most visual parameters remained within normal ranges. NPA showed no significant change for OD (p = 0.085) and OU (p = 0.279), but a small significant improvement was found in OS (p = 0.038), indicating only the left eye responded to BLF use. Accommodative facility (AF) improved greatly for all conditions—OD, OS, and OU (all p < 0.001)—with binocular AF increasing from 12.56 to 13.87 cpm, showing faster focusing ability with BLF. NPC values showed minimal changes: Break increased slightly from 6.04 to 6.10 cm and Recovery from 9.38 to 9.47 cm, both statistically significant (p = 0.046 and p = 0.006) but not clinically meaningful, indicating almost unchanged convergence performance. Vergence facility (VF) improved from 15.16 to 15.91 cpm with BLF (p < 0.001), showing better binocular flexibility, though the effect size is small.The AC/A ratio remained unchanged at 0.25 under all conditions (p = 0.42 and p = 0.31), confirming that BLF has no effect on the accommodative–vergence interaction. Symptoms like burning, tearing, eye pain, dryness and headache were significantly reduced after using the BLFLs while using digital devices. Others symtoms also shows minimal effect after using BLFLs than compared without BLFLs use.  Conclusion: This study demonstrates that short-term use of blue light filter lenses (BLFL) during laptop-based tasks leads to measurable improvements in visual function. A modest enhancement in accommodative parameters and slight improvement in vergence performance indicate reduced visual load when blue-light exposure is minimized. Participants also reported a clear reduction in visual discomfort, showing that BLFL lessen acute digital eye strain. Overall, BLFL act as an effective, non-invasive optical aid that supports more stable accommodative and binocular responses while improving visual comfort during short-duration laptop use.

Keywords : Accommodation, Vergence, Visual Comfort, Blue Light, AC/A Ratio, Blue Light Filter Lens, Digital Task.

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