Optics and Refraction Flashcards
6 cards from real Vision and Ophthalmology practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 Optics and Refraction flashcards as text
A patient who is myopic has a far point located:
Answer: In front of the eye at a finite distance
A myopic eye is too long or too powerful, focusing parallel rays in front of the retina; the far point is at a finite distance in front of the eye.
Which type of lens is used to correct myopia?
Answer: Concave (minus) lens
Concave (diverging, minus) lenses diverge light rays before they enter the eye, effectively moving the focal point back onto the retina in myopic patients.
Presbyopia results from decreased ability of the lens to:
Answer: Accommodate (change shape) for near vision
Presbyopia occurs due to age-related loss of lens elasticity and ciliary muscle effectiveness, reducing the amplitude of accommodation needed for near focus.
In a spherocylindrical lens, the power is equal in all meridians in which component?
Answer: Sphere only
The spherical component of a lens has equal power in all meridians, while the cylindrical component adds power in only one meridian to correct astigmatism.
What does the term 'axis' refer to in a cylindrical lens prescription?
Answer: Direction of no power (plano meridian)
The axis in a cylinder prescription specifies the meridian of no cylindrical power (the plano meridian), perpendicular to which the full cylinder power acts.
Anisometropia refers to a significant difference in refractive error between:
Answer: The two eyes
Anisometropia is a condition where the two eyes have significantly different refractive errors, which can lead to amblyopia if uncorrected in childhood.