Optical Instruments — Flashcards

Flashcard 1: Which type of ophthalmoscopy is based on the principle of making the patient's eye highly myopic?

Answer: Indirect ophthalmoscopy

Extra: In indirect ophthalmoscopy, a high-power convex lens (condensing lens) is used to make the patient's eye highly myopic, allowing a real, inverted image of the fundus to be formed in the air between the lens and the observer.

Flashcard 2: Orthokeratology is used for treatment of _____

Answer: myopia (hypermetropia/myopia)

Flashcard 3: _____ reflex in retinoscopy is seen in keratoconus

Answer: Scissoring

Flashcard 4: Contrast sensitivity is assessed using _____.

Answer: Pelli-Robson chart

Flashcard 5: 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 6: Which type of retinoscope projects a linear beam of light that can be rotated to identify the axis of astigmatism?

Answer: Streak retinoscope

Extra: Unlike the spot retinoscope, the streak retinoscope (e.g., Copeland's) produces a linear beam of light. By rotating the streak, the clinician can align it with the principal meridians of the eye to accurately determine the power and axis of astigmatism.

Flashcard 7: The total refractive power of lens in reduced eye: _____ D

Answer: 17

Flashcard 8: Which device is used for performing Fincham's test?_____

Answer: Stenopaeic slit

Flashcard 9: The following retinoscope is also called _____

Answer: Priestley Smith retinoscope

Flashcard 10: What is the name of the following test used for testing colour vision? _____

Answer: City university test