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Purpose: Comparison of patient satisfaction with red?free (green) versus yellow light using binocular indirect ophthalmoscope for retinal examination. Methods: This is an observational questionnaire?based study of 100 myopes in the age group of 18–40 years coming for a routine check?up or for refractive surgery workup. The examination was done using an indirect ophthalmoscope and a 20D lens with green or yellow light and was assigned in two groups randomly using the coin toss method, following which, a questionnaire was used to assess the following parameters: a) level of comfort, b) any complaints of discomfort during examination, d) preference of the used light source in future, e) grading of discomfort on a linear scale, and f) patient cooperation and duration of examination. Results: Patients were randomized for observation with IDO using either green light (n = 55) or yellow light (n = 45) filter. In the study, 46 patients (83.6%) were very comfortable and only 9 patients (16.4%) experienced mild discomfort when using red?free (green) light, while only 3 patients (6.7%) were very comfortable and 31 (68.9%) had mild discomfort when using yellow light. The complaints of watering with yellow and green light were noted in 36 patients (80.0%) and 15 patients (27.3%), pain in 13 patients (28.9%) and 3 patients (5.5%), light sensitivity in 29 patients (64.4%) and 4 patients (7.3%), respectively, all being significantly more in yellow light category (P < 0.001). The time of examination was significantly more in yellow light category with 83 ± 10.75 seconds (P < 0.001). Conclusion: Retinal examination using the green filter of indirect ophthalmoscope is more comfortable in examining the patients as compared to routine yellow light with decreased number of complaints, lesser examination time, and better patient cooperation.
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Myopia is one of the most common ocular problems,which causes visual dysfunction.The prevalence of myopia is increasing,while the prevention and treatment have made no breakthrough because the pathogenesis and mechanism of myopia remains unclear.Certain kinds of molecules were reported to play a role in myopia,such as dopamine,retinoic acid,glucagon,ZENK (Zif269、EGR-1、NGFI-A or Krox-24) etc.As a derivative of vitamin A,retinoic acid is the final metabolite of retinaldehyde,which combines to opsin in the photoreceptor cells on retina.Previous studies demonstrated that retinoic acid from choroid and retina plays significant roles in the development of myopia,which affects different molecules related to myopia development,including transforming growth factor-β,glycosaminoglycan,matrix metalloproteinase (MMP)-2 and tissue inhibitor of metalloproteinase (TIMP)-2.Based on the synthesis,mechanism and effects of the retinoic acid in the eye,this paper describes the new progress of retinoic acid in experimental myopia,including form deprivation myopia,defocus induced myopia and monochromatic myopia,hence offers new clues for the research on the mechanism of myopia.
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Background Research showed that exposure of 530 nm monochromatic light can induce myopia in animal,and retinal Müller cells participate in the formation of myopia.However,the effect and mechanism of retinal Müller cells during the formation of monochromatic light induced-myopia is below understood.Objective This study was to investigate biologic characteristics of rat retina Müller cells and the expression of cell factors in Müller cells after being illuminated by the 530 nm monochromatic light,and discuss the role of the retina Müller cells in myopia induced by monochromatic light.Methods Immortalized rat retinal Müller cells were cultured with DMEM containing 10％ fetal bovine serum in a self-made cell incubator with monochromatic light by adjusting luminance of 530 nm LED source.The cells were exposed to 125,250 and 500 lx luminance respectively for 6,12 and 24 hours,and the cells without light-irradiation were used as control.The growth of the cells under the different light time and different illuminations was described by MTT as the absorbance at the wavelength 570 nm (A570),and cell cycle analysis of Müller cells was performed by flow cytometry 48 hours after cultured,and the expression of transforming growth factor-beta 1 (TGF-β1),tyrosine hydroxylase(TH),inducible nitric oxide synthase(iNOS) and basic fibroblast growth factor(bFGF)in the cells were detected by reverse transcription PCR(RT-PCR),respectively.Results The Müller cells were uniform in size with polygonal shape and defined edges.No statistically significant difference was found in the A570 value in the cells of the 125 lx and 250 lx illuminated groups compared with the control group in various time points(P＞0.05).However,significant lowing was seen in the A570 value in the cells of the 500 lx illuminating for 12 hours and 24 hours in comparison with the control group (P =0.013,0.001).Compared with the control group,the ratio of the number between G2 and G1 phase was not significantly declined in 125 lx,250 lx illuminating for 48 hours (P =0.073,0.330),and the ratio in the 500 lx illuminating group was significantly lower than those in the 250 lx illuminated group and the control group (P =0.028,0.038).RT-PCR revealed that the expression of TGF-β1 mRNA in the cells was higher in the 250 lx illuminated group than that of the 500 lx illuminated group (P=0.006).The expression of iNOS mRNA was gradually upregulated in the 250 lx illuminated group compared with the control group (P =0.001),but that in the 500 lx illuminated group was downregulated (P =0.000).The expression of bFGF mRNA was raised in the 125 lx and 250 lx groups but reduced in the 500 lx group when compared with the control group(P=0.002,0.000,0.005).Also,the expression of TH mRNA was significantly increased in the 250 lx group(P=0.000),but decreased in the 500 lx group(P=0.000,P=0.001).Conclusions The monochromatic light of 530 nm can inhibit the growth of rat Müller cells and downregulate the expression of myopia-related cell factors and therefore exert effect in the formation of myopia.
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Objective In the early life period when eyes grow rapidly,visual experience can play an important role in axial growth and refractive development. For instance, depriving the eye of form vision during infancy will accelerate axial growth, resulting in substantial amounts of myopia, called form deprivation myopia (FDM). Similarly, imposing the eye with a negative lens produces compensating myopic growth in many species, called defocus induced myopia (DIM) . As one of the important visual experiences,color vision and its effects on eye growth deserve to be investigated. The purpose of this study was to investigate the effect of 530 nm monochromatic light and establish an innovative model of myopia in guinea pig by exposing to this monochromatic light. Methods Twenty male guinea pigs at 2 weeks old were randomly assigned to two groups (n = 10) . The experimental group was raised under the condition of 330 nm monochromatic light illumination. The control one was bred under white light illumination with 5000 k color temperature. These guinea pigs were raised in a specially designed cage. The light source was provided by specially made LEDs (green: peak value 530 nm and half bandwidth 30 nm; white: color temperature 5000 K) . The illumination parameters of the two groups were identical and the light quantum number was 3 x 10~(-4)μmol·cm~(-2)·s~(-1) . Through measuring,the irradiance value was 0.150 mW·cm~(-2) for green light and 0.247 mW·cm~(-2) for white light approximately. All animals were kept under a 12/12 h light/dark cycle (light: 8 a.m. - 8 p.m. ) ,in the temperature of 22℃ - 26℃ and a relative humidity of 55% -65% . Both groups underwent biometric measurement including refraction,corneal curvature and axial length,etc. before and after twelve weeks treatment. The refraction was examined using a streak rednoscope and trial lenses in a dark room one hour after topically administering a cycloplegic eye drop. The radius of comeal curvature was measured with a keratometer (Topcon OM-4, Japan) and axial components was measured by A-scan ultrasonagraphy ( Opticon Hiscan A/B).Repeated measurements were undertaken. Only the right eye's parameters of each guinea pig were used for analysis. Unpaired (-tests were used in all comparisons between the two groups of eyes with a statistical analysis software (Stata, version 7.0) . Results Before treatment, the refraction of experimental group was 4.6 ± 0.59 D.and that of the control group was 4.63 ± 0.48 D. The axial and vitreous body length was 7.48 ±0.11 mm and 3.16 ±0.07 mm in the experimental group,respectively,and 7.55 ±0.16 mm,3.21 ±0.09 mm in the control. The differences between the biometric parameters of the two groups including refraction, comeal curvature and axial components were not significant ( P > 0.05) . However,after a twelve-week exposure, the variation of refraction in the experimental group was -3.125 ± 0.76 D,and - 1.075 ± 0.71 D was observed in the control group. There was a 2.0 D myopia in the experimental group compared with the control. Axial length grew 0.98 ± 0.13 mm in the experimental group and 0.77 ± 0.22 mm in the control. Vitreous body extended to 0.33 ± 0.14 mm and 0.13 ± 0.14 mm in the two groups, respectively. The refraction of the experimental group shifted more towards myopia ( P < 0.0001) accompanied with a more accelerated speed of axial growth and vitreous body's extension ( P < 0.05) compared with that of the control group. There were no significant differences in the radius of comeal curvature, the depth of anterior chamber and the lens thickness between the eyes of the two groups at the end of the experiment ( P > 0.05) . Conclusion The 530 run monochromatic light can accelerate the prolongation of axial length and vitreous body inducing axial myopia in guinea pigs.
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Objective To study the effect of monochromatic light on the distribution of retinal ganglion cells in chicks. Methods Sixty One-day-old male broilers were reared under four light treatments,red(660nm),green(560nm),blue(480nm) and white(400-760nm) by using LED(light-emitting diodes) as light sources until the 49th day(n=15).Light intensity was 15 lux at the height of birds' heads and scheduled for 23hours of light and 1hour of darkness during the entire experiment.The retinas were stained by Nissl-staining and DiI-labeling.The retinal area,cell size and density in ganglion cell layer were estimated by image analysis. Results The retinal area and RGCs' number in the blue and green light groups were higher than that in the red and white light groups(10.35% and 17.07%,P