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Tian Tian, Hong Liu, Rui Liu; Effects of 0.5Hz and 20Hz Flash 530nm Monochromatic Illumination on Refraction Development in Guinea Pigs. Invest. Ophthalmol. Vis. Sci. 2018;59(9):682.
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© ARVO (1962-2015); The Authors (2016-present)
Our previous experiments showed that guinea pigs exposed to steady long wavelength light (530nm) became myopic and that low flash frequency white light could produce a myopic refractive shift as well. Recent studies reported that high flash frequency light attenuated form-deprivation myopia and lens-induced myopia in chickens. We want to investigate the effects of different frequencies of flash light on emmetropization under 530nm illumination.
Forty-eight two-weeks-old guinea pigs were randomly divided into four groups: steady white light, steady green light, 0.5Hz flash green light, and 20Hz flash green light. Light emitting diode (LED) tubes (peak value 530 nm, half bandwidth 30 nm) were used for green illumination and LED (color temperature 5000 K) for white illumination. Flash frequency were controlled via temporal luminance modulation (0.5Hz: 1s bright and 1s dark ; 20Hz: 0.025s bright and 0.025s dark). Illumination intensity in four groups were controlled at 800lux by luminometer. Refraction, axial length, and corneal curvature were measured by streak retinoscopy, A-scan ultrasonography, and keratometry, respectively, before and after 2, 4, 6, and 8 weeks of treatment.
(1)Refraction in steady green light decreased toward myopia compared with steady white light group (p<0.05). (2)No significant difference in refraction was observed between the 20Hz flash green light group and steady white light group. (3)Refraction in 0.5Hz flash green light group decreased toward myopia compared with the steady white light group(p<0.05). (4)No significant difference in refraction was observed between the 0.5Hz flash green light group and steady green light group. (5)Axial length in steady green light, 0.5Hz flash green light, and 20Hz flash green light group grew longer compared with steady white light group, of which 0.5Hz flash green light group was the longest(p<0.05). (6)No significant difference in corneal curvature was observed in steady white light, steady green light, and 0.5Hz flash green light group. However, the corneal in 20Hz flash green light group was the flattest(p<0.05).
Eyes can integrate the two visual experiences: color and luminance flicker, in the process of emmetropization. The two visual cues are most likely to affect the emmetropization through different mechanisms.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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