Eye Problems and Diagnosis

The Optic Disc, Refraction, Visual Acuity, and Astigmatism 1. Explain why vision is lost when light hits the blind spot. 2. Match the terms in column B with the descriptions in column A. Column AColumn B light bending 2. ability to focus for close (less than 20 feet) vision 3. normal vision 4. inability to focus well on close objects (farsightedness) 5. nearsightedness 6. blurred vision due to unequal curvatures of the lens or cornea 7. medial movement of the eyes during focusing on close objects a. accommodation b. astigmatism c. convergence d. emmetropia hyperopia f. myopia g. refraction 3. Complete the following statements: In farsightedness, the light is focused the retina. The lens required to treat myopia is a _2_ lens. The “near point” of vision increases with age because the _3_ of 1.1m image that is upside down and reversed from left to right. Such an image is called a A image. 1. 2. 3. 4. 4. Use terms from the key to complete the statements concerning near and distance vision. (Some choices will be used more than once.) a. contracted b. decreased c. increased d. loose e. relaxed f. taut During distance vision, the ciliary muscle is the ciliaryr zonule is the convexity of the lens is and light refraction is . During close vision, the ciliary muscle is the ciliary zonule is lens convexity is , and light refraction is 5. Using your Snellen eye test results, answer the following questions. Is your visual acuity normal, less than normal, or better than normal? Explain your answer. Explain why each eye is tested separately when an examiner is using the Snellen eye chart. Explain 20/40 vision. Explain 20/10 vision. 6. Define astigmatism. How can it be corrected? 7. Define presbyopia. What causes it? Rlinanpqq 8. To which wavelengths of light do the three cone types of the retina respond maximally? , and 9. How can you explain the fact that we see a great range of colors even though only three cone types exist? Binocular Vision 10. Explain the difference between binocular and panoramic vision. What is the advantage of binocular vision? What factor(s) are responsible for binocular vision? Eye Reflexes 11. In the experiment on the convergence reflex, what happened to the position of the eyeballs as the object was moved closer to the subject’s eyes? Which extrinsic eye muscles control the movement of the eyes during this reflex? What is the value of this reflex? 12. In the experiment on the photopupillary reflex, what happened to the pupil of the eye exposed to light? What happened to the pupil of the nonilluminated eye? Explanation? Ophthalmoscopic Examination 13. Why is the ophthalmoscopic examination an important diagnostic tool? 14. Many college students struggling through mountainous reading assignments are told that they need glasses for “eyestrain.” Why is it more of a strain on the extrinsic and intrinsic eye muscles to look at close objects than at far object