The optics of the eye
The eye as an optical instrument: the cornea and lens, accommodation, the dioptre, vision defects (myopia, hyperopia, presbyopia, astigmatism) and their correction, the retina with its cones and rods.
- 34 cards
- 3 topics
- Free
The outline, topic by topic
Each topic is weighted the way the exam weighs it.
- Concepts
- Scenarios
- Understand
A few cards from the deck
Cornea: what is it?
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The clear lens at the front of the eye, providing about two thirds of its optical power.
Laser refractive surgery corrects vision by reshaping it.
A child struggles to see the board but reads a book well. Which defect and which correction?
- Myopia, corrected with diverging lenses
- Hyperopia, diverging lenses
- Presbyopia, converging lenses
- Cataract, no correction
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Myopia, corrected with diverging lenses
A myope sees clearly up close without effort; far away, the image falls in front of the retina.
Lens: what is it?
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The flexible lens behind the iris, whose curvature changes to focus.
Its clouding with age is cataract.
Why does the cornea bend light more than the lens?
- It is thicker
- It can accommodate
- It is coloured
- The step from air into the cornea is the eye's biggest jump in refractive index
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The step from air into the cornea is the eye's biggest jump in refractive index
Underwater, the cornea loses this power: vision blurs without a mask.
Accommodation: what is it?
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The lens's increase in power to see clearly up close, through contraction of the ciliary muscle.
It weakens with age, leading to presbyopia.
At 50, a person holds the newspaper farther away to read it. Why?
- Starting myopia
- Presbyopia: the lens no longer accommodates enough
- A complete cataract
- Colour blindness
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Presbyopia: the lens no longer accommodates enough
Plus reading glasses compensate.