Ophthalmology General dcc81312 The most common cause of myopia is – A A–P diameter is increased B The thickness of lens is increased C The viscosity of aqueous humour is increased D The viscosity of vitreous humour is increased High-Yield Explanation A most common type of myopia and hypermetropia are axial, i.e. in myopia axial length of eyeball increases and in hypermetropia, it decreases.