Optics and Refraction — Flashcards

Flashcard 61: _____ test is used to distinguish whether the colored halos are due to cataract or glaucoma.

Answer: Fincham's

Flashcard 62: Stenopaeic slit can be used to determine the axis of the cylinder in _____.

Answer: astigmatism

Flashcard 63: The total refractive power of the human cornea is approximately: _____ D

Answer: 43

Extra: • Total refractive power of the eye (Reduced eye): 60 D • Corneal power: +43 D (approx. 2/3 of total power) • Lens power: +15 to +19 D (approx. 1/3 of total power) Note: In the 'Reduced Eye' model, the eye is simplified to a single refracting surface with a total power of 60 D. The value 43 D specifically refers to the cornea in a standard schematic eye.

Flashcard 64: The _____effect is one of the natural mechanisms that decrease aberration in the eye.

Answer: Stiles Crawford 

Flashcard 65: _____ hypermetropia: Masked by the tone of the ciliary body

Answer: Latent

Flashcard 66: _____ images are reflections of objects from the structure of the eye.

Answer: Purkinje

Flashcard 67: The retinoscope consisting of a plane mirror with a central aperture is also called _____

Answer: Priestley-Smith retinoscope

Extra: The Priestley-Smith retinoscope is a type of reflecting retinoscope consisting of a plane mirror with a central aperture. It is less commonly used today compared to self-illuminated streak retinoscopes.

Flashcard 68: What refractive error is commonly associated with pterygium?_____

Answer: Astigmatism

Flashcard 69: _____ is the gold standard instrument for the quantitative assessment of color vision

Answer: Nagel's anomaloscope

Flashcard 70: Moderate myopia, when the error is _____D.

Answer: -3 to -6