Below is a common instrument used in ophthalmology. In order to view the entire retina what is the power of lens you would like to attach to the instrument: (A) +90 D, (B) +78 D, (C) -58 D, (D) +20 D
Answer is D. Ans. (d) +20 DRef: Yanoff & Ducker 4/e, p. 89*Instrument is indirect ophthalmoscope.*Condensing lens commonly used is 20D biconvex lens.#Magnification=PoweroflensPowerofeye =20D60D =3times