AIM:To explore the etiology distribution of non-strabismic diplopia with first symptom of diplopia.METHODS:Non-strabismic diplopia patients (69 cases) with first symptom of diplopia underwent routine examination,uncorrected visual acuity,corrected visual acuity,refractive status,anterior segment and fundus examination.After that,according to the movement examination of monocular and binocular,the binocular visual function,the convergence function by synoptophore,Maddox Rod Test were applied.According to illness history,eye specialist examination,systemic examination and consultations advice,etiology distribution of the disease was analysed.RESULTS:Patients(32 cases) with convergence insuffi-ciency was the most common reason.Corneal astig-matism from pterygium surgery( 8 cases),early cataract(8 cases),lens or artificial lens subluxation (4 cases),after cataract (3 cases),glaucoma (2 cases),macular epiretinal membrane(2 cases),retinal detachment (2 cases),vitreous liquefaction (1 case),posterior vitreous detachment (1 case),double pupils caused by trauma (1 case),postoperative pathologic high myopia (1 case),and unknown reasons (4 cases) were all the causes of this disease.CONCLUSION:In the non-strabismic diplopia with first symptom of diplopia,the convergence insufficiency is the most common etiology.There is similar proportion in the patients of monocular/binocular diplopia and young/age.