Optics and Refraction — Flashcards

Flashcard 91: The concept of reduced eye was introduced by _____

Answer: Listing (later simplified by Donders)

Flashcard 92: Magnification produced by indirect ophthalmoscopy is approximately _____ times

Answer: 2-5

Flashcard 93: The angle subtended by the largest letter on the Snellen chart at 60m distance is _____.

Answer: 5 minutes (5')

Flashcard 94: _____ can be used to find out the optimal site for optical iridectomy in case of corneal opacities

Answer: Stenopaeic slit (Device)

Flashcard 95: The refractive index of the lens in the nucleus is _____

Answer: 1.41

Flashcard 96: Refractive power (dioptre) =  1/_____

Answer: Focal length in metres

Flashcard 97: The total refractive power of lens in reduced eye: _____ D

Answer: 17

Flashcard 98: Which color vision test involves matching a central colored spot to one of four peripheral colored spots?

Answer: City University Test

Flashcard 99: High myopia is defined as a refractive error of _____ D or more.

Answer: -6

Flashcard 100: The tolerable limit of aniseikonia is _____%?

Answer: 5-8%

Extra: Aniseikonia is a condition where there is a difference in the size or shape of the images seen by the two eyes. • **Tolerable limit:** Generally up to 5% (some sources cite up to 8% as the upper limit for fusion). • **Clinical significance:** Differences >5% usually lead to symptoms like headache, eye strain, and eventual loss of binocular single vision (fusion failure).