ABSTRACT
Objective To observe c-Fos expression in visual cortex of infant rhesus monkeys with myopia induced by hyperopic defocus and preliminarily investigate the possibility of visual cortex participating in myopia. Methods Eight SPF grade healthy infant rhesus monkeys aged 20 to 30 days were randomly divided into hyperopic defocused group and control group,4 monkeys for each group. The monkeys in hyperopic defocused group wore -3 D spectacle lenses. The monkeys in control group wore 0 D lenses. The monkeys' refractive error,corneal topography, vitreous chamber depth were measured at the start of lens wear and at 2,4,6,8,12 weeks post-treatment. At 12 weeks post-treatment,the visual cortex tissues were removed for c-Fos protein measurement by immunohistochemistry and Western blot assays. The results were analyzed semiquantitatively to compare the differences of c-Fos expression between hyperopic defocused group and control group. The use and care of the animals complied with Regulations for the Administration of Affair Concerning Experimental Animals by State Science and Technology Commission. This study protocol was approved by Ethic Committee of Zhongshan Ophthalmic Center ( No. 2013-014). Results After 12 weeks'lens wear,the vitreous chamber elongation amplitude of hyperopic defocused group monkeys was more obvious than that of the control group ([0.93±0.24]mm vs. [0.72±0.09]mm;t=2.292,P=0.047). The decrease of hyperopic degrees of hyperopic defocused group monkeys was more obvious than that of the control group ([-3.23± 1.36]D vs. [-1.55±0.52]D;t=-3.273,P=0.006). The eyes of hyperopic defocused group monkeys appeared a remarkable myopic shift after treatment. The number of c-Fos immunoreactive neurons was less in the hyperopic defocused group than that in the control group,with a statistically significant difference between them ([1 843±191]/mm2vs. [2 296±503]/mm2;t=2.381,P=0.041). Western blot assay showed that the optical density of c-Fos protein in the hyperopic defocused group was significantly less than that in the control group (0.50±0.17 vs. 0.99± 0.22;t=-4.982,P<0.01). Conclusions Hyperopic defocus,as an abnormal visual stimulus,can induce the onset of myopia in infant rhesus monkeys and inhibit c-Fos expression in visual cortex. Visual cortex may participate in myopia induced by hyperopic defocus.
ABSTRACT
Background Horizontal sulcus-to-sulcus (STS) and white-to-white diameter are important parameters for designing the proper size of collamer implantable contact lens (ICL).Inappropriate size of ICL may induce the complications postoperatively.Several previous studies compare horizontal STS and white-to-white diameter in normal eyes have been reported,but seldom in high myopic eyes.Objective This study was to investigate the discrepancy of STS diameters in 4 axes and analyze the relationship between horizontal STS diameter and white-towhite diameter in high myopia eyes.Methods The STS diameters in 4 axes (45,90,135 and 180 degrees) and the white-to-white diameters were measured in 48 eyes of 26 high myopia patients using the 50 MHz ultrasound biomicroscopy (UBM),the Orbscan-Ⅱ topography system,and the IOL Master,respectively.The mean spherical was (-12.93±3.87) diopters (D) (-8 to-20 D).Statistical evaluation was performed using the one-way ANOVA for comparison of measurement.The agreement of three devices was assessed using the Bland and Altman method.Results The mean STS diameter at 45,90,135 and 180 degrees was (12.06±0.50) mm,(12.27±0.50)mm,(12.03±0.46) mm and (11.84±0.47)mm,respectively.The 90 degree STS was significantly larger than other STS diameters (all at P＜0.05).The 180 degrees STS was significantly shorter than other STS diameters (all at P＜0.05).However,there was no significant difference between 45 degree STS and 135 degree STS (P=0.817).The mean WTW was (11.56±0.40) mm with Orbscan Ⅱ z topography system and (11.98±0.41) mm with IOLMaster.The WTW measured with Orbscan Ⅱ z was significantly shorter than the 180 degrees STS (t =-4.384,P =0.000).The WTW measured with IOLMaster was significantly larger than the 180 degrees STS (t =2.368,P =0.000).Bland-Altman analysis showed not very well agreement for measurements of WTW,STS between Orbscan Ⅱz and UBM,IOLMaster and UBM,Orbscan Ⅱ z and IOLMaster,the width of 95％ confidence interval (CI) were-0.57 to 1.12 mm,-0.96 to 0.67 mm,-0.73 to-0.13 mm,respectively.Conclusions The STS diameters in 4 different axes are not identical with each other in high myopia eyes.The longest STS is in the vertical meridian,the shortest STS is in the horizontal meridian.The WTW diameter measured with both Orbscan Ⅱ z and IOLMaster are not precise for calculating the horizontal STS in high myopia eyes.Three instruments cannot be interchanged for calculating the size of ICL.