1. CAUSES & FUNCTIONAL IMPLICATIONS OF VISUAL IMPAIRMENT The eyes and associated structures must be normal in structure & function. The neurological pathways from the retina & optic nerve to the visual cortex must be in tact. The brain must be capable of interpreting the information received.

2. What does 20/20 mean? Numerator is distance patient is from chart (usually 20 feet) Denominator is how far away a person with normal (emmetropic) vision can see that letter on the chart. Your distance 20/40 how far away a normal eye could be

3. VISUAL IMPAIRMENT 20/200 central acuity Less than 20 degrees of visual field

4. Conditions That Result In Low Visual Acuity Ocular muscle disorders- eyes that are not in proper alignment

5. Strabismus & Amblyopia Defects of the eye muscle system Can result in loss of vision in one eye due to lack of use

6. phoria- tendency of eye to deviate, particularly when fatigued or fusion broken tropia- marked deviation of an eye.

7. Esotropia- turning in of one or both eyes Exotropia- turning out of one or both eyes

8. Hypertropia- turning up of one or both eyes Hypotropia- turning down of one or both eyes

9. Nystagmus Null point- point of least nystagmus & best vision Pendular nystagmus- up-and-down movements of equal speed, amplitude & duration Jerk nystagmus- slower movement in one direction

10. Typoscope

11. Disorders Relating to the Shape of the Eye Refractive Disorders

12. Myopia- nearsightedness Hyperopia- farsightedness

13. Anisometropia- more than 1 diopter difference in refractive error between both eyes Aniseikonia- difference in shape or image received by both eyes

14. Microphthalmia- abnormally small eye Macrophthalmia- abnormally large eye Anophthalmia- underdeveloped or nondevelopment of eyes

15. Lid Anomalies Entropion- lid turns in Ectropion- lid turns out Ptosis- droopy eyelids

16. Corneal Disorders & Diseases Astigmatism

17. A. Keratoconus- cornea cone-shaped –1.extreme type of corneal curvature B. Keratitis- inflamed or ulcerated cornea 1. ocular herpes 2. STDs- clamidia, syphilis, gonococcal C. Corneal dystrophies 1. genetic D. Corneal scarring

18. Disorders Relating to Absent or Dysfunctional Irises Aniridia –Aniridia.org

19. Dysfunctional iris- does not constrict or dilate Coloboma or iris or choroid- keyhole- shaped iris Iritis- inflammation of iris

20. Lens-Related Conditions Presbyopia less flexible lens due to aging

21. Cataracts- opacity of the lens Pseudophakia- intraocular lens (IOL) Aphakia- no lens Dislocated lens

22. Types of Cataracts Juvenile Sutural Posterior subcapsular (PSC) Senile

23. Diseases of Anterior Segment Glaucoma- –Open angle –Closed angle –Congenital glaucoma –Peters anomaly

24. Signs & Symptoms of Glaucoma Signs –High intraocular pressure (IOP) –Cupped disc –Increased angle of anterior segnment Symptoms –Pain if pressures very high –Progressive loss of visual field

25. Disorders Relating to Vitreous Opacities vitrectomy- removed of portion of vitreous due to opacity

26. Retinal Disorders 2 visual systems of eye –Central, color vision (photopic) –Peripheral, nigh, movement vision (scotopic)

27. Color Deficiencies Achromatopsia- lack of color vision –Often accompanied by photophobia (light sensitivity) & nystagmus –Genetic abnormality of color receptors

28. Albinism NOAH.org Lack of pigment –pink eyes –nystagmus, photophobia, strabismus, low acuity Ocular albinism –blue eyes –nystagmus, photophobia, strabismus, low acuity

29. Retinal edema swelling of the retina

30. Diabetic retinopathy proliferative diabetic retinopathy- vitreous pulls away from retina, vessels hemorrhage nonproliferative diabetic retinopathy- microaneurisms

31. normal retinalasered retina

32. proliferative diabetic retinopathy

33. Retinopathy of Prematurity fibrovascular proliferation into the vitreous refractive errors, amblyopia, strabismus, nystagmus, glaucoma, cataracts, corneal changes, retinal-vitreous abnormalities Treatment: laser therapy on avascular retina to anchor; scleral buckling

34. ROPARD.org Stage 3 & 4 ROP

35. Conditions Resulting Central Visual Loss Macular degeneration –Best's vitelliform degeneration- macular lesions, sometimes minor visual loss –Stargardt-Behr disease- rapidly progressive, RPE degeneration Age-Related Macular Degeneration (ARMD) -wet -dry Cone dystrophies- ERG detects loss of cone function -Central scotoma- "blind spot“ leading to eccentric viewing

36. NormalDryWet MaculaARMDARMD

37. Central Field Loss ARMD, Cone dystrophy, Bests, Stargardts

38. Peripheral field impairments hemianopsias- compressive lesions on optic nerves retinal detachments retinitis pigmentosa- field loss, night blindness, cataracts glaucoma chorioretinitis

39. Hemianopsia

40. Retinal detachments High myopia Cataract surgery Trauma Retinopathy of prematurity Posterior vitreous detachment Lattice degeneration

41. Retinitis Pigmentosa retinitis pigmentosa- night blindness, field loss, cataracts begins in the first decade of life, gradually progressive Usher syndrome when associated with sensorineural deafness genetic

42. RP

43. Glaucoma

44. Retinal Eye Diseases Chorioretinitis Rubella Toxoplasmosis Cytomegalovirus

45. normal retinacytomegalovirus

46. Chorioretinitis Inflammation of the uveal tract, choroid and/or retinal Results in scotomas (blind spots)

47. Combined Central & Visual Field Impairments Coloboma- embryonic defects resulting in incomplete formation of the lids, iris, retina and/or choroid Optic nerve disorders & diseases Optic atrophy- disorder of the optic nerve interrupting transmission of visual stimuli Optic nerve hypoplasia & septo-optic dysplasia- optic nerve fails to develop Strokes

48. Coloboma CHARGE syndrome –Coloboma & cranial nerves –Heart problems –Atresia of the choanae –Retardation of growth & development –Genitourinary abnormalities –Ear & hearing abnormalities

49. Cortical Visual Impairment Disturbance of visual pathways and/or occipital cortex Inconsistent vision due to processing issues Causes can be asphyxia, ischemia, head injury, brain defects, infection or hydrocephalis

50. Leber’s Optic Neuropathy This is a rare inherited condition which involves the optic nerves with either complete or partial loss of central vision. The optic nerve is the "information cable" joining the eye, the "camera", to the brain. If damage occurs to the retina or the optic nerve then some of the "wires" in the optic nerve will die. A healthy nerve looks pink and one that has been damaged pale and is called "atrophic". In LHON the nerve can look abnormally pink and slightly swollen Normally males lose their eyesight between the ages of 15 and 45. Often vision is lost in one eye a few months before the other. There is loss of central vision and diminished colour vision. Children will have difficulty with reading and fine detail tasks especially with low contrast and small detail work.

51. Optic Neuritis Inflammation of the optic nerve. Eye can be painful on movement. Contrast vision generally permanently decreased. Highly correlated with multiple sclerosis Retrobulbar- behind the eye

52. Optic Atrophy Pale optic nerve Visual loss Congenital or adventitious Loss of fibers that transmit visual impulses

53. Optic Nerve Hypoplasia Congenital underdevelopment of optic nerve Appears small and pale Nystagmus is common

54. Conditions Caused by External and Other Factors Monocularity- use of one eye Trauma –puncture wounds –sympathetic ophthalmia –blunt trauma – burns Electromagnetic radiation Disorder caused by tumors of the eye – retinoblastoma –melanoma versus nevus Conjunctivitis- allergic, vernal, chemical, fungal, bacterial, viral

55. Genetically Determined Conditions autosomal recesive autosomal dominant sex-linked

56. Perceptual Difficulties Dyslexia & learning disabilities Scintillating scotomata/migraine Charles Bonnet syndrome

57. Cortical Vision Loss damage of one or both occipital lobes of visual cortex

58. Progressive Visual Impairment regular eye care & self-monitoring diabetes posterior vitreous detachment glaucoma cataract

59. OPTICS & LOW VISION DEVICES

60. Basic Optics The Composition of Light The Measurement of Light Refraction- the bending of visible light rays –index of refraction- speed of light passing through various media Refraction & the ocular system

61. The Optics of Lenses Structure of a lens Snell's law- the line that will travel upon exiting glass focal point or image point- where light rays come together & converge on a point

62. Types of lenses spherical lenses –convex or plus lenses bulge outward –planoconvex- bulges on one side –chromatic aberration- light disperses as are colors in a prism –biconcave- bulges inward on both planes –planoconcave- bulges inward on one side – cylindrical lenses –plano lenses- lens cut flat on both sides –combination of lenses –prism lenses- moves light rays into functional field

63. Lenses for Refractive Errors Myopia (nearsightedness) = biconcave (minus) Hyperopia (farsighted) = biconvex (plus) Astigmatism (irregular cornea) = cylindrical + axis (location on cornea) Strabismus = prisms (base in or out)

64. Measurement of Lenses focal distance- fd power is measured in diopters D

65. Types of Magnification Relative distance magnification Relative size magnification Angular magnification Projection magnification

66. Near Vision Optical Devices Microscopes Magnifiers handheld magnifiers bar magnifiers

67. Near Vision Optical Devices Stand magnifiers Illuminated magnifers

68. Distance Vision Optical Devices Telescopes Hand-held monocular telescopes Clip-on monocular telescopes

69. Spectacle-mounted telescopes full-field telescope systems bioptic telescopes Contact lens telescopes Behind-the-lens telescopes

70. Non-Optical Systems Illumination 1. types of light 2. position of light 3. adaptation of light to dark 4. glare Illumination control Nonoptical magnification

71. Electronic Systems Common electronic systems Closed circuit TVs (CCTVs) Computer systems Other magnification systems

72. Field-Expansion Systems Bioptics Fresnel prisms