Unit II Refractive errors of eye

1. Unit II Refractive errors of eye Presented by HezilReemaBarboza

2. Refractive errors of eye

4. Refractive errors imperfections in the focusing power of the eye, for example, hyperopia( hypermetropia) myopia, and astigmatism. Hyperopia (Long sightedness) Myopia (Short sightedness) Astigmatism

5. DEFINITION A refractive error prevent light rays from converging into a single focus on the retina Defects are results of irregularies of the corneal curvature the focusing power of the lens or the length of the eye

6. When the light rays are focused in front of the retina, the resulting condition is termed Myopia (short-sightedness). In Hyperopia (long-sightedness), the light rays come to a focus behind the retina. Astigmatism (cylindrical error) occurs when incoming light rays are unable to reach a common focus within the eye.

7. Common refractive disorders Myopia - nearsightednesss (distant objects are blurry) Hyperopia- farsightedness (close objects are blurry) Presbyopia (aging of the lens in the eye where there is inability to accommodate for near objects) Astigmatism (blurred vision at all distances caused by irregular corneal curvature)

8. Normal vision

9. Myopia

10. Causes • caused by the eyeball being too long. This causes the light rays to focus in front of the retina.

11. Symptoms of myopia Children complain of their inability to see the blackboard. Shortsighted people often have headaches or suffer from eyestrain. They have blurry distant vision

13. Causes • Hyperopia occurs due to the length of the eyeball being much shorter than usual. • As a result, light rays entering into the eye focus behind the retina opposed to directly on it.

14. Symptoms of hyperopia Long sighted patients have a blurred vision of close objects. They suffer from eye strain and headache after doing close work. Irritability and nervousness after prolonged concentration.

16. Causes • It is caused by an irregularly shaped cornea. Usually shaped like a baseball, an eye with astigmatism will have a football shaped cornea.

17. Symptoms of astigmatism Patients with astigmatism have blurred or distorted vision at all distances. It can also cause images to appear doubled, particularly at night. Patients have inconsistent difficulty focusing on various objects such as finely printed words and lines. Headache and fatigue are common as the person tends to strain their eyes. Squinting, eye discomfort and irritation are also frequent.

18. Treatment Refractive disorders are commonly treated using corrective lenses, such as eyeglasses or contact lenses. Refractive surgery can also be used to correct some refractive disorders.

19. Presbyopia • Presbyopia is an inescapable refractive error that naturally occurs with age. Like hyperopia, presbyopia causes near vision to be blurry.

20. Causes • Presbyopia occurs naturally with age. It is caused by the gradual thickening and loss of flexibility of the lens inside your eye.

21. Symptoms • close work, such as handwriting, may cause headaches or eye strain.

22. Diagnosis • A comprehensive eye examination

23. Treatment • For those who are symptomatic,glasses, contact lenses, refractive surgery, or a combination of the three are typically used.

24. Refractive errors: correction Non surgical options for the correction of refractive errors include spectacles and contact lenses. Spectacles contain lenses that suitably refract the incoming rays of light and enable them to focus on the retina. Contact lenses perform the same function but are placed on the cornea-the clear front portion of the eye.

25. Correction of myopia Radial Keratotomy, where four to eight corneal incisions are made involving 95-99% of the corneal thickness, to flatten the central corneal. The weakened peripheral cornea is pushed outwards by the pressure within the eye. This results in a flattening of the central cornea which corrects a myopic refractive error.

26. Correction of hyperopia Hexagonal Keratotomy A incisions is made in a hexagonal fashion in the mid-peripheral cornea result in a forward protrusion of the central cornea.

27. Correction of astigmatism • Straight or curved incisions are made in the mid peripheral cornea and the procedure is termed Astigmatic Keratotomy.

28. Other surgical therapy • Laser: • Laser assisted in situ keratomileusis (LASIK) • Photorefractive keratectomy (PRK)

29. IMPLANTS • Intra corneal ring segment • Refractive intraocuar lens • Phakic intraoccular lenses

30. Thermal proedures • Laser thermal keratoplasty • Conductive keratoplasty

31. Nursing diagnosis • Disturbed sensory perception related to visual deficit • Self care deficit related to visual impairment • Grieving realted to loss of functional vision • Risk for injury related to inability to see potential dangers

32. Summary • Refractive error is a problem with focusing of light on the retina due to the shape of eye • The most common types of refractive errors are hyperopia, myopia, and astigmatism

33. Evaluation • Name the refractive errors of eye? • Explain the causes, symptoms and management of astigmatism? • Differentiate between myopia and hyperopia

34. References • Smeltzer SC, Bare BG, Hinkle JL, Cheever KH. Text book of medical surgical nursing. 11th ed. New Delhi: WoltersKluwerPvt Ltd; 2009. • Lewis, Dirkson, Heitkemper,Bucher. Lewis's Medical Surgical Nursing. India: Elsevier;2011.