Intervention of blue light with short wavelength on the progression of form deprived myopia in guinea pigs

Abstract

Background Light stimulation at different wavelength influences the development of eyes.It has been showed that blue light can inhibit the growth of eyeball.To study whether blue light exposure can delay the extension of myopia is an interested research project.Objective This study was to investigate the effect of blue light with short wavelength on ocular growth in form deprived myopia (FDM) in guinea pigs and provide a new option for the prevention and treatment of myopia.Methods Thirty-six 2-week-old guinea pigs were reared in the environment of white light.The right eyes of the animals were occluded to establish the FDM models.The models were randomized into the deocclusion + blue light exposure group,simple deocclusion group and continuous occlusion group according to the random number table.The right eyes of the models were deoccluded for 1 hour per day to give the blue light (430 nm) irradiation in the deocclusion + blue light exposure group,and the right eyes were deoccluded for 1 hour per day only in the simple deocclusion group.In the continuous occlusion group,the right eyes of the models were occluded until the end of this experiment.Anterior chamber depth (ACD),lens thickness (LT) and vitreous cavity depth (VCD) were measured by A-type sonography.The binocular diopter of the guinea pigs was detected using retinoscopy in the mydriatic condition.In the fourth week after experiment,the retinal sections were prepared for the regular histopathological examination,and the scleral tissues next to 1 mm from optical nerve were exacted to obtain the dry weight of scleral tissues.Results In the right eyes of the animals,no significant differences were found in the diopter,ACD,LT and VCD before experiment among the 3 groups (all at P＞0.05).At the end of experiment,the refraction of right eye in the deocclusion + blue light exposure group,simple deocclusion group and continuous occlusion group was (+1.11±0.17)D,(+0.90±0.15)D and (-2.73±0.19)D respectively,with a significant difference among them (F=1 445.470,P=0.000).The VCD in the three groups was (3.70±0.09) mm,(3.78±0.11) mm and (3.91 ± 0.08) mm,respectively,showing a significant difference (F =13.243,P＜0.01).In addition,the dry weight of sclera tissues was (0.61 ±0.09)mg in the deocclusion + blue light exposure group,(0.54± 0.08)mg in the simple deocclusion group and (0.43 ± 0.07)mg in the continuous occlusion group,with a significant difference among the 3 groups (F=10.458,P＜0.01).However,there were no significant differences in the ACD and LT among the 3 groups (F=0.203,0.084,both at P＞0.05).Moreover,in the left eyes,no significant differences were found in the diopter,ACD,LT and VCD before experiment among the 3 groups (all at P＞0.05);while at the end of the experiment,the diopter of the continuous occlusion group was significantly lower than that of the deocclusion + blue light exposure group and simple deocclusion group (all at P＜0.05).No significant differences were seen in the ACD,LT,VCD and dry weight of sclera among the 3 groups (all at P＞0.05).Retinal structure was normal in the left eyes of various groups.However,the retinas were thinner in the right eyes of the deocclusion + blue light exposure group with clear layers; while atrophy of the outer segment of photoreceptor and disorder of cell arrangement were seen in the right eyes of the continuous occlusion group.Conclusions During sensitive period of visual development,blue light stimulation can arrest the extension of posterior sclera and elongation of vitreous cavity,which restrains development of myopia.This blue light at the wavelength of 430 nm is safe to retina. Key words: Blue light/short wavelength; Ametropia/form deprived; Myopia; Ocular growth; Sclera; Guinea pig