Vision Science II opto 5221 May 3, 2004 Final Examination



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Vision Science II

Opto 5221

May 3, 2004

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.

d. refractive index of the lens cortex, the cornea gets flatter, and anterior chamber gets deeper.

e. refractive index of the lens cortex, in addition there is an increase in the radii of curvature of the crystalline lens and corneal surfaces, and anterior chamber gets deeper.


3. Which of the following statements concerning the emmetropization process is NOT correct?

a. The eyes of myopic newborns grow toward a low degree of hyperopia.

b. Emmetropization is largely complete in human infants by about 12-18 months of age.

c. The eyes of most children become more isometropic during emmetropization.

d. Anisometropia below 1.5 D is frequently transient during emmetropization.

e. Premature infants weighing less than 1500 grams are frequently more hyperopic than full term infant and they become even more hyperopic over the first year of life.


4. Which of the following statements concerning the development of youth-onset myopia is NOT correct?

a. The onset of youth-onset or juvenile-onset myopia typically occurs between 8-10 years of age.

b. Following the onset of myopia, the average annual progression rate is about 0.5 D per year.

c. The progression of youth-onset myopia is highly correlated to vitreous chamber elongation rates.

d. The rate of progression is independent of the age of onset of myopia.

e. In general the earlier the onset of myopia the greater the final degree of myopia.


5. Which of the following structures/pathways is essential for the development of form-deprivation myopia?

a. parasympathetic input to the eye

b. ciliary body

c. visual cortex

d. Edinger-Westphal Nucleus

e. retina


6. Which of the following parts of the eye reach adult-like dimensions at the earliest age?

a. cornea

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.


12. Which of the following statements concerning treatment strategies for myopia is NOT correct?

a. Recent studies have shown that progressive addition lenses produce a small, but statistically significant reduction in the progression rate of myopia.

b. Topically applied anti-glaucoma drugs that reduce intraocular pressure do not prevent or slow down the progression of myopia.

c. Topically applied atropine slows the progression of myopia because it produces cycloplegia.

d. Pirenzepine is a relatively selective cholinergic muscarinic antagonist that has been shown to slow the progression of juvenile onset myopia in a dose dependent fashion.

e. There is little evidence that prescribing base-in prism for near work reduces the progression of juvenile onset myopia.


13. Based on population statistics, if both parents are myopic, a normal full-term infant is __________.

a. about 4 to 5 times more likely to become myopic than the offspring of emmetropic parents.

b. more likely show a higher degree of myopia at 4 years of age than at 14 years of age.

c. less likely to exhibit emmetropization during the first 12 months of life than the offspring of emmetropic parents.

d. more likely to exhibit with-the-rule astigmatism than the offspring of emmetropic parents.

e. unlikely to exhibit any significant astigmatic errors during the first 4 years of life.


14. Which of the following statements concerning the refractive characteristics of the eye is NOT correct?

a. The axial lengths for +2 to +4 D hyperopes are typically within the range of axial lengths for the emmetropic population.

b. The amount of astigmatism found at 6 months of age is not very predictive of an individual’s astigmatism at 20 years of age.

c. Young myopes with refractive errors larger than -6 D almost always have axial lengths that fall outside the range of axial lengths for the emmetropic population.

d. The distribution of corneal powers in a population of young adult emmetropes is leptokurtic.

e. Refractive astigmatism found before 18 months of age is due primarily to the shape of the cornea.


15. Which of the following statements concerning refractive development is NOT correct?

a. Children who have hyperopic errors greater than +1.5 D at age 6 years will typically stay hyperopic.

b. The prevalence of astigmatism greater than 1 D is higher at 6 months of age then at 6 years of age.

c. Children who have refractive errors less hyperopic/more myopic than +0.5 at age 6 years will typically become myopic in the next 5-6 years.

d. Form deprivation myopia occurs in many species including humans.

e. The axial elongation associated with juvenile onset myopia occurs because the sclera actively grows and increases in mass and thickness.





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