Short-term effects of different wavelengths on axial length with induced optical defocus among emmetropes

Purpose. Mobile phone usage is widespread in the digital age, potentially affecting eye health. This study aims to evaluate the effect of mobile screen exposure to different wavelengths, along with induced myopic and hyperopic defocus. Material and methods. A pre- and post-test quasi-experimental research of 50 emmetropic undergraduate students with a mean age of 20.68 ± 0.98 years were performed at the Pakistan Institute of Ophthalmology, Al-Shifa Trust Eye Hospital, Rawalpindi, Punjab, Pakistan, utilizing non-probability judgmental sampling. Those without ocular or general health issues and no significant refractive error on retinoscopy were included. Axial length (AL) was measured using the IOL Master 800 after thorough eye and visual examinations. An Android mobile application “Flash Screen” exposed participants to violet, blue, yellow, white, green, and red light. Myopic defocus was induced using +3.00 D lenses and hyperopic defocus with -3.00 D lenses. Jaffery Amazing Statistical Package (JASP) analyzed data. Results. Baseline axial length (AL BL) was 23.235 ± 0.657 mm. AL changed significantly after exposure to violet, blue, yellow, white, green, and red light with and without induced myopic (MD) and hyperopic (HD) defocus. Significant AL decreases (p < 0.001) were seen under violet and blue light settings, with an effect size (ES) at 1.000. Under hyperopic defocus, green and red light revealed considerable alterations (p < 0.001), with significant negative impacts. Yellow light barely changed AL. Conclusion. Emmetropes exhibit AL changes to different wavelength as per longitudinal chromatic aberrations, and dominate optical defocus effect.

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