Optics and Refraction Principles Flashcards
7 cards from real Board Certified Ophthalmologist practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Optics and Refraction Principles flashcards as text
A Galilean telescope uses a +5.00 D objective and a -20.00 D eyepiece. What is the separation between the lenses?
Answer: 15 cm
The tube length equals the sum of focal lengths: 20 cm + (-5 cm) = 15 cm.
In unilateral aphakia, which correction method produces the least aniseikonia?
Answer: Posterior chamber intraocular lens
An IOL near the eye's nodal point causes about 1-3% magnification, compared with about 7-10% for contact lenses and 25-33% for spectacles.
Which bifocal segment design minimizes image jump?
Answer: Flat-top segment
The flat-top segment's optical center lies near its top edge, so little prism is introduced as the eye enters the segment.
Which prism orientation is used in spectacles to relieve symptomatic exophoria at near?
Answer: Base-in
Base-in prism shifts the image outward, reducing the convergence demand for an exodeviation.
What is the definition of one prism diopter?
Answer: Displacement of 1 cm at a distance of 1 m
One prism diopter deviates light 1 cm at 1 m, which is roughly 0.57 degrees for small angles.
How is the transmission axis of polarized sunglasses oriented to reduce glare from horizontal surfaces such as water?
Answer: Vertically
Light reflected from horizontal surfaces is mainly horizontally polarized, so a vertical transmission axis blocks it.
Using the SRK regression formula, an axial length error of 1 mm results in approximately what IOL power error?
Answer: 2.5 D
In the SRK formula (P = A - 2.5L - 0.9K), the axial length coefficient is 2.5 D per mm.