Accommodation,Convergence And Stereopsis Analysis After Wearing Plus 0.75 Additional Lens In Myopia Development

Introduction and ObjectiveThe prevalence of Myopia is growing worldwide.The controlling of myopia development is regarded as the key point in recent years.Previous studies have revealed that accommodative function could be enhanced by decreasing accommodative lag after attaching additional positive spherical lens all refractive error was corrected.The interaction between Accommodative function,convergence function divergence function and steroscopic vision is complex and they are also key factor to evaluate binocular vision especially after wearing additional lens.This project is proposed to investigate the effect of plus +0.75 D lens on binocular vision in aspect of accommodative function,convergence and divergence function and steroscopic vision.The findings unrevealed in this study could provide new approach of controlling myopia development.Methods(1)Subjects: 98 subjects who are physically and mentally healthy were recruited,according to refraction error,the subjects were divided intu three group: emmetropia group(EMM),low myopia group(LOM),moderate myopia group(MOM).According to ocular position and Morgan standard value,the subjects were divided into normal group(N),exophoria group(EXO),esophoria group(ESO).(2)+0.75 D was selected according to proper accommodative response after 2months pilot study.(3)Accommodative function examination and evaluation: positive and negative spherical lens of comprehensive refractometer with near vision card,open field of vision and infrared automatic computer refractometer,flip with near vision card were used to measure accommodative amplitude,accommodative reaction and the accommodative sensitivity,and calculating the accommodative lag and fluctuation to evaluate their accommodative ability.(4)Convergence and divergence function examination and evaluation: the rotary prism of comprehensive refractometer was used to measure negative and positivefusional convergence and divergence to evaluate fusional function of binocular visual function.(5)Stereopsis examination and evaluation: Titmus stereogram with polarized glasses was used to exam stereoscopic vision sensitivity to evaluate their stereopsis.(6)Asthenopia evaluation: questionnaire was used to analyse the asthenopia.Results Main results were grouped according to different diopter:(1)Accommodative function: The study found that there was a negative correlation relationship between amplitude and fluctuation of accommodation in the condition that all refractive error was corrected.Accommodative lags of three groups were higher compared with normal group,in which accommodative amplitude of LOM group was the lowest worst and accommodative fluctuation was high.Accommodative lags of three groups recovery to normal condtion and the accommodative fluctuation of LOM group and MOM group was decreased with additional +0.75 D.(2)Convergence and divergence function: In the condition that all refractive error was corrected,the worst function of positive fusional convergence and divergence was found.Positive fusional convergence and divergence range of EMM group and LOM group was decreased,and the LOM group negative fusional convergence and divergence range was improved with additional +0.75 D.(3)Stereopsis: There was no difference in stereoscopic acuity of three groups.But Steroscopic vision of three groups raised with additional +0.75 D.(4)Asthenopia: In the condition that all refractive errorwere fully corrected.Asthenopia of LOM group and MOM was much serious than EMM group.The asthenopia of EMM group and MOM group was relieved,while LOW group was serious with additional +0.75 D.Main results were grouped according to different ocular position:(1)Accommodative function: In the condition that all refractive error were corrected,Accommodative lags of three groups were higher than normal group,in which accommodative lag of ESO group was the highest and accommodativefluctuation of ESO was largest.Accommodative lags of three groups were decreased to normal range and the accommodative fluctuation of three groups was decreased with additional +0.75 D.(2)Convergence and divergence function: In the condition that all refractive error were corrected,negative fusional convergence and divergence range of EXO group was larger than ESO group,but positive fusional convergence and divergence range of ESO group was larger than EXO group.Positive fusional convergence and divergence range of N group and ESO group was decreased,and negative fusional convergence and divergence range of the N group was raised with additional +0.75 D.(3)Stereopsis: There was no difference in stereoscopic acuity of three groups in the condition that all refractive error was corrected.But Stereopsis of three groups was raised with additional +0.75 D.(4)Asthenopia: In the condition that all refractive error was corrected,Asthenopia of the ESO group was serious than other groups.There was no change in asthenopia of N group and ESO,but the asthenopia of the EXO group was more serious with additional +0.75 D.Conclusion(1)Accommodative function and stereopsis of subjects was improved with additional + 0.75 D.It suggested that +0.75 D is suitable for most of the people.(2)Accommodative ability of EMM group and MOM group was strengthen with their positive convergence and divergence function decreased and stereoscopic acuity strengthen;Accommodative ability of LOM group was improved with positive fusional convergence and divergence ability decreased and asthenopia ocurred.It suggested that high-add condition may cause a decline in accommodation and positive fusional convergence and divergence ability.So it needs to review visual function regularly if there is a positive lens attached.Positive fusional convergence and divergence ability reserve must be examed.If a person has poor positive fusional convergence and divergence ability and accommodation reserve,additional positive lens should be used with caution.(3)After attaching +0.75 D,accommodative ability increased,positive fusionalconvergence and divergence decreased and asthenopia occurred of EXO group.And accommodative ability and positive fusional convergence and divergence increased of ESO group.It indicates that ESO group is high-risk groups for myopia and additional positive lens should be used with caution of positive fusional convergence and divergence of EXO group.(4)Comprehensive Analysis indicated that additional positive lens could be suitable for the people who have high accommodative lag,high accommodative fluctuation and enough accommodative and positive convergence and divergence reserve to increase visual function to prevent and control the occurrence and development of myopia.