<prompt> Which of the following is contrast sensitivity testing cha?PellirobsonsSnellen type chaRegan chaAll of the above  <response>: Contrast sensitivity is affected by various factors like age, refractive errors, glaucoma, amblyopia, diabetes, optic nerve diseases and lenticular changes. Fuher, contrast sensitivity may be impaired even in the presence of normal visual acuity. Reference : A K KHURANA COMPREHENSIVE OPHTHALMOLOGY, Edition4 ,page-17 