Final Examination Multiple choice - mark the most appropriate answer on the computer scoring sheet. If you have concerns over a given question, write you concerns on your test and turn it in with your answer sheet. Be sure to put your name on the test and indicate on the top of the front page which questions I should examine.
Note: Unless otherwise specified all refractive errors are principle plane or ocular refractive errors. Use Emsley’s reduced eye model for all calculations unless specified otherwise. RSM=relative spectacle magnification; SM=spectacle magnification.
1. Which of the following statements concerning the distribution of spherical equivalent refractive errors in the general US population is NOT correct?
a. In comparison to a random distribution, the distribution for a young adult population is leptokurtic with more clinical emmetropes, fewer individuals with moderate refractive errors (e.g., -3.0 D), and more individuals with larger refractive errors (>+6.0 D).
b. The refractive error distribution is most like a random distribution for individuals older than 60-70 years of age.
c. In comparison to young adults, the refractive error distribution for a population of 2-3 year olds exhibits less variance, i.e., refractive errors are less variable at 2-3 years of age.
d. Between 25 and 60 years of age the peak of the refractive error distribution shifts in a hyperopic direction.
e. For a young adult population, the shape of the refractive error distribution is influenced by the vocation of the individuals in the sample.
2. During the first 3 years of life the reduction in the eye’s total refractive power is due primarily to an increase in the ________.
a. radii of curvature of the crystalline lens surfaces, in addition there is a relative increase in the refractive index of the lens core, the cornea gets flatter, and anterior chamber gets shallower.
b. radii of curvature of the crystalline lens surfaces, in addition the cornea gets flatter and the anterior chamber gets deeper.
c. radii of curvature of the cornea, in addition the crystalline lens gets flatter and the anterior chamber gets deeper.
6. Which of the following parts of the eye reach adult-like dimensions at the earliest age?
b. anterior chamber depth
c. crystalline lens thickness
d. crystalline lens curvature
e. vitreous chamber depth
7. Which of the following statements best describes refractive errors in twins?
a. Even when raised in separate environments, uniovular twins almost always have very similar refractive errors and show a high degree of concordance between individual ocular components.
b. Uniovular twins may have very different refractive errors, but they will typically show a high degree of concordance between at least 4 individual ocular components.
c. Uniovular twins almost always have very similar refractive errors, however, the degree of concordance between individual ocular components is no higher than it is in dizygotic twins.
d. If biovular twins grow up in similar visual environments, they almost always have very similar refractive errors and show a high degree of concordance between individual ocular components.
e. For refractive errors between -6 D and +4D, the degree of concordance between individual ocular components is approximately the same for monozygotic (uniovular) and diyzgotic twins.
8. Which of the following statements best summarizes the corneal changes in a normal adult between the ages of 35 and 55 years?
a. There is an equal decrease in radius of curvature for all corneal meridians.
b. There is a selective increase in the radius of curvature of the vertical meridian.
c. There is an overall decrease in radius of curvature and the horizontal meridian changes more than the vertical meridian.
d. There is an overall decrease in radius of curvature and the vertical meridian changes more than the horizontal meridian.
a. There is an equal increase in radius of curvature for all corneal meridians.
9. Which of the following factors is probably responsible for the decrease in hyperopia / increase in myopia typically observed after about 65-70 years of age.
a. the onset of absolute presbyopia and the total loss of accommodation.
b. an effective forward shift of the crystalline lens.
c. a relative increase in the refractive index of the crystalline lens core in comparison to the lens cortex.
d. a relative increase in the refractive index of the crystalline lens cortex in comparison to the lens core.
b. an increase in vitreous chamber depth.
10. Which of the following statements concerning the implications of lens-rearing experiments in laboratory animals on the phenomenon of emmetropization is NOT correct?
a. The emmetropization process has a limited operating range and refractive errors that fall outside this range produce unpredictable growth.
b. The eye uses visual feedback associated with the eye’s effective refractive status to guide ocular growth toward emmetropia.
c. Brief daily periods of unrestricted or clear vision have a stronger effect on eye growth in young animals than much longer daily periods of either form deprivation or hyperopic defocus.
d. In agreement with animal studies, clinical studies have demonstrated that “undercorrecting” young myopes reduces the progression of axial myopia.
e. Emmetropization comes about primarily as a result of vision-dependent control over axial growth.
11. Which of the following statements concerning the effects of visual experience on emmetropization is NOT correct?
a. The potential for a clear retinal image is essential for normal emmetropization.
b. Late onset myopia is caused by over accommodating during near work.
c. Although LAISK procedures can correct the optical errors associated with myopia, these surgical procedures do not reduce the extra risk for retinal detachment associated with high degrees of myopia.
d. Viewing conditions that have been shown to produce hyperopic growth in young animals can also produce an increase in the thickness of the choroids.
e. Form deprivation myopia can be prevented by the topical application of the dopamine agonist, apomorhine, or antagonists to vasoactive intestinal peptide.