<prompt> Commonest cause of uniocular diplopiaCataractSubluxated lensThird nerve palsyAstigmatism  <response>: In Unilocular diplopia an object appears double from the affected eye even when the normal eye is closed. CAUSES Subluxated clear lens. Subluxated intraocular lens. Keratoconus irregular refraction from corneal surface Double pupil congenital large iridectomy iridodialysis Incipient cataract this usually causes polyopia - due to irregular refraction due to multiple water clefts within the lens Ref;A.K.Khurana; 6th edition; Page no:344 