| Part1Effects of three muscarinic receptor antagonists on form deprivation myopia in guinea pigsPurpose:To investigate the effects of non-selective muscarinic receptor antagonists on form deprivation myopia in guinea pigs.Material and Methods:Sixty guinea pigs, aged from2to3weeks, were randomly divided into six groups, ten in each group:form deprivation group as Group I, from deprivation plus saline group (negative control group) as Group II, from deprivation plus tropicamide group as Group III, from deprivation plus cyclopentolate group as Group IV, from deprivation plus atropine group as Group V, and normal control group as Group Ⅵ. Form deprivation was only performed in right eyes with translucent membranes in Group I. In Group II, III, IV, V, form deprivation was performed in right eyes with intravitreal injection of seven times of10μ10.9%saline,0.5%tropicamide,1%cyclopentolate, or0.5%atropine in the same eyes at four-day intervals, respectively. Both eyes were open in Group VI. All the left eyes served as group control. Refraction was measured by retinoscopy after cycloplegia. Axial lenth, anterior chamber depth, lens thickness were measured by A-scan ultrasound, then vitreous chamber depth was calculated. The guinea pigs were euthanized at the end of experiment and ocular enucleation was performed. The axial lengths of enucleated eyes were measured with vernier caliper. Paired t-test was performed to compare intra-group differences. One-way analysis of variance (ANOVA) was used to compare inter-group differences. Linear regression was applied to assess the relationship between the differences in vitreous chamber depth and axial length in experimental eyes and contralateral eyes. A significance level of P<0.05was used for all tests.Results:After4weeks of treatment, relative myopia of-5.11±1.78D,-5.75±2.27D,-5.50±1.47D,-4.20±2.06D,-2.13±0.48D were induced in form deprived eyes in Group Ⅰ, Ⅱ, Ⅲ, Ⅳ, and Ⅴ, respectively. Differences in the relative myopia amount between Group VI and Group Ⅰ, Ⅱ, Ⅲ, and Ⅳ were statistically different (all P<0.0001). The vitreous chamber depths of experimental eyes were0.2907±0.1358mm,0.2886±0.0946mm,0.1208±0.1867mm,0.2259±0.2814mm, and0.1268±0.1540mm longer than those of the contralateral eyes in Group Ⅰ, Ⅱ, Ⅲ, Ⅳ, and Ⅴ, respectively. No statistically significant difference was found in the vitreous chamber depths between experimental and contralateral eyes among the6groups. Axial lengths in the experimental eyes were0.2083±0.0758mm,0.2829±0.0765mm,0.0904±0.1740mm,0.0969±0.0647mm, and0.0923±0.1304mm longer than those of the contralateral eyes in Group Ⅰ, Ⅱ, Ⅲ, Ⅳ, and Ⅴ, respectively. The difference in axial length between the experimental and contralateral eyes in Group Ⅵ was statistically significantly different from that of Group Ⅰ and Ⅱ (P=0.003, P<0.0001, respectively), but was not significantly different from that of Group Ⅲ, Ⅳ, and Ⅴ. There was a positive correlation between the differences of vitreous chamber depth and axial length in experimental eyes and contralateral eyes. The axial length measured by vernier caliper was significantly longer than that measured by A-scan ultrasound (8.43±0.26mm VS8.09±0.12mm, P<0.0001)Conclusion:All the three non-selective muscarinic receptor antagonists in this study can reduce axial elongation of form deprived eyes in guinea pigs. The increase in vitreous chamber depth was consistent with that in axial length. The axial length measured by vernier caliper is longer than that measured by A-scan ultrasound. Part2Clinical trial of0.05%racanisodamine in myopic childrenPurpose:To investigate the effect of non-selective muscarinic receptor antagonist, racanisodamine on myopia control in children.Subjects and Methods:Ninety-three school age children with reasonable expectation and written informed consent were recruited in optometry center of Fudan University Eye and ENT Hospital. Inclusion criteria were:①age between6and14years;②spherical refractive error between-6.00and-0.5diopter (D), and astigmatism no more than1.5D;③clear visual pathways in both eyes;④free from eye diseases. Participants were divided into2groups:treatment group (n=50) and control group (n=43). Children in the treatment group were administrated with0.05%racanisodamine drops on a nightly basis for one year. Children in the control group did not receive any treatment. The average age was9.94±1.97years for the treatment group and10.64±1.52years for the control group. The mean baseline spherical equivalent (SE) and axial length (AL) were-2.14±1.60D and24.23±0.80mm for the treatment group, and-2.28±0.78D and24.59±0.72mm for the control group, respectively. Subjects were required to follow up every half year and this study ended in one year. Participants underwent subjective refraction and AL measurements using IOL Master. Independent t test was performed to compare the SE and AL between groups at various follow-up time points. A significance level of P<0.05was used for all tests.Results:Mean SE was-2.60±1.69D and-3.35±1.40D for the treatment group, and-2.64±0.82D and-3.09±0.90D for the control group in month6and12, respectively. The differences between groups were not statistically significant (P=0.99, P=0.17). The mean increases in myopia in month6and12were-0.47±0.75D and-0.42±1.16D for the treatment group, and-0.33±0.37D and-0.45±0.35D for the control group, respectively. The differences between groups were not statistically significant (P=0.11, P=0.79). Mean ALs were24.52±0.80mm and24.97±0.76mm for the treatment group, and24.75±0.72mm and24.88±0.74mm for the control group in month6and12, respectively. The differences between groups were not statistically significant (P=0.06,, P=0.55). Mean increases in AL were0.30±0.34mm and0.25±0.14mm for the treatment group, and0.17±0.10mm and0.12±0.09mm for the control group, respectively. The differences between groups were statistically significant (P<0.001, P<0.001)Conclusion:0.05%racanisodamine has no effect on reducing the progression of myopia and elongation of AL in children. The potential efficacy of0.05%racanisodamine in some children needs further exploration. |
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