Which of the following is contrast sensitivity testing cha?: (A) Pellirobsons, (B) Snellen type cha, (C) Regan cha, (D) All of the above
Answer is D. 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