Optics and Refraction Indian Medical PG Flashcards - Medical Study Cards
Master Optics and Refraction with OnCourse flashcards. These spaced repetition flashcards are designed for medical students preparing for NEET PG, USMLE Step 1, USMLE Step 2, MBBS exams, and other medical licensing examinations.
Optics and Refraction Flashcard Deck - 10 Cards
Flashcard 51: 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 52: Near point becomes _____ in hypermetropia.
Answer: distant (closer/distant)
Flashcard 53: Refractive index of the lens: _____
Answer: 1.40
Flashcard 54: _____ theory states that there are three separate color systems (retinexes).
Answer: Edwin Land's
Flashcard 55: Jaeger s chart is held at a distance of _____ cm away from patient.
Answer: 35
Flashcard 56: Which type of ophthalmoscopy can be performed through a poorly dilated pupil?
Answer: Direct ophthalmoscopy
Extra: Direct ophthalmoscopy provides an erect, virtual image with high magnification (15x) and a small field of view (approx. 10°). Because the illumination and observation paths are nearly coaxial, it can be performed through a poorly dilated or undilated pupil. In contrast, indirect ophthalmoscopy requires a dilated pupil to accommodate the separate illumination and observation light paths.
Flashcard 57: FOV produced by direct ophthalmoscopy is limited to _____
Answer: 2 DDs
Flashcard 58: Examination through hazy media is possible in which type of ophthalmoscopy?
Answer: Indirect ophthalmoscopy
Extra: Indirect ophthalmoscopy uses a brighter light source and allows the examiner to bypass media opacities (like cataracts) more effectively than direct ophthalmoscopy.
Flashcard 59: The fundus in hypermetropia may show _____
Answer: pseudopapillitis
Flashcard 60: 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.
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