| Objective:Myopia now is the most common eye disease,causing public health problems and social problems all over the world.Myopia can affect many parts of one's life such as students' physical health,learning,career choices,social activities for young people,and the selection of the national defense forces.Besides,high myopia patients,especially those with degenerative or pathological changes,such as retinal detachment,macular degeneration,glaucoma and cataract,their chance s of getting permanent vision loss and blindness are also higher.Studies have shown that the global prevalence of myopia is about 30%(3%-84%),and East Asia has the highest prevalence of myopia with 40%~70% incidence.Among all the countries,China has the highest number of myopic patients in the world.Research data indicates that with more and more academic burden and long term near work,prevalence of myopia in adolescents is gradually increasing in East Asia and China.According to the data of Ministr y of health and the Ministry of education,the incidence of myopia in China is about 60%,ranking the world's top second.Myopia has become a major public health and social concern of the whole society.As a megalopolis,the myopia condition of students i n Shanghai is even worse.An investigation on students' physique and health in 2010 showed that the rates of poor eyesight of students with different ages remains stubbornly high,higher than the national level and the level of 2005.Thus to investigate th e myopia condition of students in different area of Shanghai has positive meaning for prevention and treatment of myopia.In this study,we aimed to investigate the myopia condition of primary school students in Jiading area of Shanghai city,evalu ate the accommodative response of primary school students with different refractive status and analyze parameters of accommodative response of primary school students with different refractive status.The study further revealed relationship between lag of accommodation and myopia development in primary school students,as well as provide scientific basis for prevention and treatment of myopia.The contents of the study includes: 1.myopia condition of primary school students in Jiading area of Shanghai;2.comparison of accommodative response among students with different ages and gender;3.accommodative demand,response and accommodative lag under different reading distances;4.accommodative demand,response and accommodative lag of primary school students with different refractive status under different reading distances;5.comparison of accommodative demand,response and accommodative lag between dominant and non dominant eyes.Methods:1.The study selected young children in Jiading area of Shangha i city,students in grade 1 to 5 were selected randomly.All guardians of the children signed the informed consent.2.Optometry examination was conducted by a same optometrist using desktop computer automatic refractometer,analog eye calibration was performed before test.After cycloplegia,binocular diopter was evaluated in triplicate,no measurement difference was beyond 0.50 D.After subjective optometry the best corrected visual acuity was recorded and the subjective optometry was repeated the next day.The best prescription for glasses was obtained.3.Frame glasses were used for children using the best prescription under a mirror eye distance of 12 mm.Accommodative response was evaluated for 5 times using open field infrared autorefractor for all prim ary school students under distances of 0.33 m and 6m.The average values were recorded.4.The SPSS018.0 was used to analyze the data,independent continuous variables were compared using the t-test and categorical data were compared using the chi square test or Fisher exact test.Rank sum test was used if data was non normal distribution.Pearson or Spearman method was used in correlation analysis.Results:1.A total of 520 primary school students in Jiading area was selected,with a mean age of 10.00±1.39(7~15years old),male:female 286:234,a mean height of 125.62±18.16 cm and a mean weight of 28.16±12.50 kg.2.All children were divided into 3 groups according to spherical equivalent after vision correction : myopia 278 eyes with myopia,735 eyes with emmetropia,25 eyes with hyperopia.And myopic eyes were further divided into mild myopia(224 eyes),and moderate myopia(54 eyes).3.To investigate the association of accommodative system and age,gender,we divided the students into several age groups,7-8,9-10,11-12,and 13-15.Results showed that except for group of 13-15 years old which had few students,rates of myopia were 7.69%,4.51%,and 11.19% for 7-9,9-10,and 11-12 years old group,respectively.Meanwhile,it was also found that in group of 7-8 yeasr old group,myopia rate was higher in boys,however in 9-10 years old group,myopia rate was higher in girls.Also analysis of gender and male with accommodative response showed that under 6m,girls' accommodative response was higher than boys of 7-12 years old group and accommodative response decrease following with age increase.But no significant difference was observed when reading distance was0.33 m.4.Accommodative demand,response and lag at distances of 6m and 0.33 m were analyzed r espectively.Results showed that at distance of 6m,accommodative demand was 0.17D±0.002 D for left eye and 0.17D±0.002 D for right eye;accommodative response was 0.09±0.41 D for left eye and 0.17±0.44 D for right eye;accommodative lag was 0.08±0.41 D for left eye and 0.00±0.44 D for right eye.At distance of 0.33 m,accommodative demand was 3.05±0.03 D for left eye and 3.05±0.03 D for right eye;accommodative response was for 2.22±0.41 D left eye and 2.18±0.44 D for right eye;accommodative lag was 0.75±0.56 D for left eye and 0.70±0.59 D for right eye.Accommodative demand and response were significantly higher at distance of 0.33 m than that of 6m,P<0.001.And accommodative lag was significantly more serious at 0.33 m than 6m,P<0.001.5.Results of accommodative parameters in children with different refractive status at different distances showed that when reading distance was 6m,in the normal group,accommodative demand was 0.17±0.002 D,significantly lower than that of 0.33m(3.06±0.03D),P<0.001;accommodative response was 0.15±0.41 D,significantly lower than that of 0.33m(2.26±0.40D);and accommodative lag was 0.02±0.41 D,significantly lower than that of 0.33m(0.64±0.54D),P<0.001.When reading distance was 6m,in the low m yopia group accommodative demand was 0.17±0.002 D,significantly lower than that of 0.33m(3.05±0.04D),P<0.001;accommodative response was-0.05±0.38 D,significantly lower than that of 0.33m(2.11±0.42D);and accommodative lag was 0.22±0.38 D,significantly lower than that of 0.33m(0.98±0.52D),P<0.001.When reading distance was 6m,in the moderate myopia group accommodative demand was 0.17±0.002 D,significantly lower than that of 0.33m(3.05±0.03D),P<0.001;accommodative response was-0.03±0.34 D,significantly lower than that of 0.33m(2.04±0.38D);and accommodative lag was 0.20±0.34 D,significantly lower than that of 0.33m(1.04±0.40D),P<0.001.6.Results of relationship between domain eye and accommodative system showed that under 6m,accommodative demand was 0.17±0.002 D in both domain and non domain eyes,accommodative response was 0.11±0.43 D,significant lower than non domain eye 0.14±0.43 D,accommodative lag was 0.06±0.43 D,significant higher than non domain eye 0.02±0.43 D,P<0.05.However under 33 cm,no significant difference was observed.Conclusion:1.26.78% students have varying degrees of myopia in children of Jiading area.the myopia rate gradually increase following with the age,and was also associated with gender;2.accommodative demand under short distance was significantly higher than the long distance,and accommodative lag of short distance was also more serious than the long distance.3.Under different refractive conditions,accommodative demand at short distance was signific antly higher than the long distance,and accommodative lag at short distance was also more serious than the long distance.4.Accommodative response and lag showed significant difference when reading distance was far,However showed no significant differen ce under short reading distance.5.The reading distance has a significant effect on the accommodative response and the accommodative lag of primary school students.A proper reading distance is one of the key components for prevention myopia in primary school students. |
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