Abstract
Purpose :
The effect of blue light in emmetropization remained controversial. This prospective and controlled study explored the effect and the possible mechanism of blue light in lens induced myopia(LIM) in guinea pigs.
Methods :
Experiment 1. Sixty 2-week-old guinea pigs were randomly divided into white light (WL, 980lux) group and blue light (BL, 430±10nm, 900lux) group. Guinea pigs in both groups wore -5D lens on right eye and only buckle with no lens on left eye. The left eyes in WL were set as control. Spherical equivalence (SE), axial length and keratometry were tested pre-, 1w, 2w and 4w post-intervention using retinoscopy, A-scan ultrasonography and keratometer, respectively. Real time PCR and Simple Western was introduced to test the expression of retinoic acid receptor β (RAR) in retina at 2- and 4-w. High performance liquid chromatography was used to detect the density of retinoic acid in retina at 4w.
Experiment 2. Twenty 2-week-old guinea pigs were divided into 2 groups, fed with retinoic acid(RA) or its synthesis inhibitor, citral. The animals were raised under WL with -5D lens on right eye. SE and axial length were recorded pre, 2w and 4w post intervention. Student t test, paired t test and Repeated Measures ANOVA were used for statistical analysis.
Results :
Experiment 1. SE, axial length and corneal curvature were comparable between the two groups and between binocular eyes before intervention. During the intervention, the right eyes in both groups shift myopia, but the eye in BL was more hyperopic than in WL at 4w(p=0.032). While the left eye in BL shift hyperopia after illumination, and was more hyperopic than the left eye in WL(p=0.024). Axial length was longer in WL correspondingly. The gene expression had no difference between the eyes in WL and BL at 2w. However, RAR of right eye was higher in BL than WL at 4w (p=0.012). The result of protein expression was consistent with the PCR result. The RA density in left eye under BL was lower than WL (p<0.05).
Experiment 2. Guinea pigs fed with RA were more myopic than the control eye in Experiment 1, while guinea pigs fed with citral were more hyperopic than control.
Conclusions :
Blue light can slow down the progression of LIM, and the mechanism may be the decrease of RA. This was confirmed by the result that RA can accelerate myopia progression and its inhibitor citral can slow down it.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.