OCULAR ANATOMY & REFRACTION
Where does light focus in myopia?
What is in front of the retina?
Which lens material provides highest impact resistance and is required for safety lenses?
What is polycarbonate?
Which part of a progressive lens contains full ADD power?
What is the Near Reference Point (NRP)?
A +6.00 D lens is decentered 5 mm temporally. Determine prism AND base direction.
What is 3Δ Base In?
A patient has a prescription of −2.00 DS. What type of vision problem are they correcting and what type of lens is required?
What is myopia and a minus (diverging) lens?
Describe the optical issue in astigmatism.
What is two focal points due to irregular corneal curvature?
Explain how refractive index affects lens thickness.
What is higher index bends light more, allowing thinner lenses?
Why must progressive lenses have sufficient B measurement?
What is to allow space for distance zone, corridor, and near zone?
Written PD = 70 mm, Actual PD = 66 mm. Describe the decentration direction.
What is temporal (out)?
A patient has an ADD of +2.00. Explain what this means in terms of their vision needs AND where this power is located in the lens.
What is presbyopia requiring additional near magnification, located in the lower portion of a multifocal lens
Explain the difference between emmetropia and ametropia.
What is emmetropia has no refractive error while ametropia includes myopia,
A high minus patient wants thinner lenses. What material should you recommend and why?
What is high index because it has a higher index of refraction, thus reducing edge thickness?
A patient complains of image jump in bifocals. What is the cause?
What is the abrupt change between the distance and the near segment?
A −8.00 D lens is decentered 2 mm nasally. What prism is induced and direction?
What is 1.6Δ Base In?
A frame is labeled 52 □ 18. Use the boxing system to determine the GCD
What is 70 mm?
Which structure contributes most to refractive power and why?
What is the cornea because it provides majority of light bending?
Recommend lens + coating combo for a patient with night driving glare and screen use, as well as has a history of an eye injury.
What is Polycarbonate with AR coating?
Compare visual experience of SV vs PAL for intermediate vision.
What is SV has no intermediate zone while PAL provides continuous intermediate through corridor?
A patient has PD error causing 3 mm temporal decentration with −10.00 D lenses. Calculate prism in EACH eye.
What is 3Δ Base Out each eye?
This structure changes shape during accommodation to help focus on near objects.
What is the crystalline lens?
Explain how accommodation changes lens shape.
What is ciliary muscle contracts causing lens to become more convex for near vision?
Differentiate AR coating vs polarized lenses.
What is AR reduces surface reflections while polarized reduces glare from horizontal surfaces?
Explain why progressive lenses have distortion in the periphery.
What is due to surface astigmatism in the blending regions?
A lens has the following prescription:
+4.00 −2.00 x 90
The lens is decentered 3 mm temporally.
Calculate the prism amount and direction
What is 0.6Δ Base In?
This part of the lensometer allows the operator to measure and neutralize prism by adjusting from 0 to 25 prism diopters in any meridian.
What is the prism compensator?