Optics & Refraction

Topics in this chapter

• Ocular Optics and Refraction
• Refractive Errors and Anisometropia
• Accommodation and Presbyopia
• Astigmatism and Keratoconus
• Spectacle and Contact Lens Correction
• Clinical Refraction and Optical Instruments

Practice questions

1. Question 1Q-3860E2

   A 35-year-old male presents with decreased vision for distance. Autorefractometry reveals a refraction of -4.00 D sphere in both eyes. The far point of this patient's uncorrected eye is located at what distance from the cornea, assuming a standard optical system?

   1. A.12.5 cm in front of the eye
   2. B.25 cm in front of the eye
   3. C.50 cm in front of the eye
   4. D.At infinity
   See the answer and solution
2. Question 2Q-B9B053

   Which of the following optical conditions is characterized by the principal meridians of the eye having different focal powers, with both meridians focusing either in front of or behind the retina, but never directly on it?

   1. A.Simple myopic astigmatism
   2. B.Compound myopic astigmatism
   3. C.Simple hypermetropic astigmatism
   4. D.Mixed astigmatism
   See the answer and solution
3. Question 3Q-5CA88B

   A 65-year-old female complains of difficulty reading small print and sewing, while her distance vision remains clear with her current glasses. This condition is primarily attributed to which of the following physiological changes?

   1. A.Opacification of the crystalline lens cortex
   2. B.Progressive decrease in elasticity of the crystalline lens and capsule
   3. C.Weakening of the extraocular muscles
   4. D.Atrophy of the dilator pupillae muscle
   See the answer and solution
4. Question 4Q-01DC1E

   During an indirect ophthalmoscopy examination using a +20 D condensing lens, what is the nature of the final image formed to the observer?

   1. A.Virtual, erect, and magnified
   2. B.Real, inverted, and magnified
   3. C.Virtual, inverted, and diminished
   4. D.Real, erect, and diminished
   See the answer and solution
5. Question 5Q-6B80E7

   A 10-year-old child undergoes cycloplegic refraction using cyclopentolate drops. The procedure of cycloplegia is essential in children primarily to paralyze which of the following structures?

   1. A.Sphincter pupillae
   2. B.Ciliary muscle
   3. C.Dilator pupillae
   4. D.Superior oblique muscle
   See the answer and solution