Neutral density filter -: (A) Amblyopia, (B) Malingering, (C) Afferent pupillary defect, (D) Efferent pupillary defect
Answer is C. Ans. (c) Afferent pupillary defectRef: Essentials of ophthalmology p. 53"Neutral density filters can be used to grade the severity of afferent pupillary defect"--Essentials of ophthalmology