History of perimetry

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History of perimetry

  1. 1. 1 Humphrey Field Analyzer II/IIi Introduction to Perimetry
  2. 2. 2 Module Objectives When you have completed this Module, you should be able to:  Understand the basic principles of Perimetery.  Identify the historical methodologies of Perimetry  Demonstrate an ability to identify the structures of the human eye.  Define Amsler Grid  Define Confrontational Test  Define Tangent Screen  Define Goldmann Perimeter Humphrey Field Analyzer II/IIi Introduction to Perimetry
  3. 3. 3 Additional information may be found in the Field Analyzer User and Service Manuals. ?? Humphrey Field Analyzer II/IIi Introduction to Perimetry
  4. 4. 4 When would a Field test be indicated??? Humphrey Field Analyzer II/IIi Introduction to Perimetry
  5. 5. 5 A Field Test would be indicated for any patient: With an elevated IOP (>21mmHg) IIntrantra OOcularcular PPressureressure Normal IOP = 12 – 22 mmHg Humphrey Field Analyzer II/IIi Introduction to Perimetry
  6. 6. 6 IOP is defined as the pressure of the fluids within the chambers of the eye. Increased pressure is caused when the normal drainage of the eye chambers is somehow blocked. This increased pressure can restrict blood flow to the Retina, which can in turn cause the Retinal cells to die. The end result is a loss of vision. Humphrey Field Analyzer II/IIi Introduction to Perimetry
  7. 7. 7 A Field Test would be indicated for any patient:  With an elevated IOP (>21mmHg) Humphrey Field Analyzer II/IIi Introduction to Perimetry
  8. 8. 8 A Field Test would be indicated for any patient:  With an elevated IOP (>21mmHg)  With a history of visual field problem or defects. Humphrey Field Analyzer II/IIi Introduction to Perimetry
  9. 9. 9 A Field Test would be indicated for any patient:  With an elevated IOP (>21mmHg)  With a history of visual field problem or defects  With complaints of re – occurring headaches Humphrey Field Analyzer II/IIi Introduction to Perimetry
  10. 10. 10 A Field Test would be indicated for any patient:  With an elevated IOP (>21mmHg)  With a history of visual field problem or defects  With complaints of re – occurring headaches  With a medical history of Hypertension Humphrey Field Analyzer II/IIi Introduction to Perimetry
  11. 11. 11 A Field Test would be indicated for any patient:  With an elevated IOP (>21mmHg)  With a history of visual field problem or defects  With complaints of re – occurring headaches  With a medical history of Hypertension  Who manifests HIGH Myopia (Nearsightedness) Humphrey Field Analyzer II/IIi Introduction to Perimetry
  12. 12. 12 Boundaries of the Visual Field Normal vision is limited to the following physical limitations: 1. Temporal (towards the temple) – 100 degrees 2. Nasal (towards the nose) – 60 degrees 3. Superior (towards the head) – 60 degrees 4. Inferior (towards the feet) – 75 degrees Humphrey Field Analyzer II/IIi Introduction to Perimetry
  13. 13. 13 Normal Boundaries of the Visual Field Temporal 100 degrees Nasal 60 Degrees Left EyeLeft Eye Right EyeRight Eye Inferior 75 Degrees Superior 60 degrees Superior 60 degrees Inferior 75 Degrees Temporal 100 degrees Humphrey Field Analyzer II/IIi Introduction to Perimetry
  14. 14. 14 Normal Boundaries of the Visual Field Both EyesBoth Eyes When the boundaries of both the left and right eyes are superimposed, a roughly circular area is common to both eyes. This is the area known as Binocular Vision, and approximately 120 degrees in size. Humphrey Field Analyzer II/IIi Introduction to Perimetry
  15. 15. 15 Historical Methodologies of Perimetry TestingHistorical Methodologies of Perimetry Testing Amsler GridAmsler Grid Humphrey Field Analyzer II/IIi Introduction to Perimetry
  16. 16. 16 Historical Methodologies of Perimetry Testing Amsler Grid An Amsler Grid (Top) or a modified Amsler Grid (Yanuzzi Card) (Bottom) can be used by the patient for self – examination of gross perimetry problems. They can be obtained from an eye practitioner. To administer the test: 1. Ensure adequate room lighting. 2. Glasses may be worn. 3. Close one eye and hold the grid at a distance of approximately 14 inches. Humphrey Field Analyzer II/IIi Introduction to Perimetry
  17. 17. 17 Historical Methodologies of Perimetry Testing Amsler Grid 4.4. Fixate on the dot in the center of the grid.Fixate on the dot in the center of the grid. 5.5. Do not allow your gaze to drift from the fixationDo not allow your gaze to drift from the fixation target.target. Do any of the lines appear crooked or bent?Do any of the lines appear crooked or bent? Do any of the boxes appear different in size orDo any of the boxes appear different in size or shape from the others?shape from the others? Are any of the lines blurry, wavy, or discolored fromAre any of the lines blurry, wavy, or discolored from the others?the others? If the answers to any of the above wereIf the answers to any of the above were YESYES, a further, a further examination should be done by a physician. Thereexamination should be done by a physician. There could be leaking or bleeding of the eye causingcould be leaking or bleeding of the eye causing pressure on the retina.pressure on the retina. Humphrey Field Analyzer II/IIi Introduction to Perimetry
  18. 18. 18 Historical Methodologies of Perimetry Testing Amsler Grid Sometimes a Patient could not see the Central fixation dot. In those cases, a grid with an X across the grid was used to help the patient fixate. Humphrey Field Analyzer II/IIi Introduction to Perimetry
  19. 19. 19 Historical Methodologies of Perimetry Testing Amsler Grid Another type of Amsler Grid used red lines on a black background. This was helpful to diagnose certain Optic Nerve and Brain tumor type disorders. Humphrey Field Analyzer II/IIi Introduction to Perimetry
  20. 20. 20 Historical Methodologies of Perimetry Testing Amsler Grid Here are some examples of the types of distortions that patients would report: Humphrey Field Analyzer II/IIi Introduction to Perimetry Scotoma Chorioretinal Scar Arcuate Scotoma Macropsia Micropsia Metamorphasia
  21. 21. 21 Historical Methodologies of Perimetry Testing Amsler Grid Patients who experience ANY of these types of distortions should consult with their physician IMMEDIATELY! Humphrey Field Analyzer II/IIi Introduction to Perimetry Scotoma Chorioretinal Scar Arcuate Scotoma Macropsia Micropsia Metamorphasia
  22. 22. 22 Historical Methodologies of Perimetry TestingHistorical Methodologies of Perimetry Testing Confrontation Test The patient would sit or stand directly across from the person administering the test. They were asked to cover one eye, and fixate on a point, usually the nose of the tester, with the eye under test. The tester would then move a stimulus, usually a flickering finger or a penlight inwardly from a point outside the patient’s visual field until the patient saw the stimulus. Because of the relative distance between the patient and the tester, the tester could compare the patient response against their own visual acuity. Humphrey Field Analyzer II/IIi Introduction to Perimetry
  23. 23. 23 Historical Methodologies of Perimetry TestingHistorical Methodologies of Perimetry Testing Confrontation Test This test could effectively test gross visual defects. Because of its inherent possibilities for error, the results were limited. Humphrey Field Analyzer II/IIi Introduction to Perimetry
  24. 24. 24 Historical Methodologies of Perimetry TestingHistorical Methodologies of Perimetry Testing Tangent Screen Humphrey Field Analyzer II/IIi Introduction to Perimetry
  25. 25. 25 Historical Methodologies of Perimetry TestingHistorical Methodologies of Perimetry Testing Tangent Screen Made of a Black felt background with circular stitching every 5 degrees, it was a simple method of perimetry testing which tested out to 30 degrees at one meter. It usually had radial stitching every 22.5 degrees. The Tangent screen was the standard test of choice for many years, and is still considered useful today with certain patients, such as those afflicted with severe Arthritis. Humphrey Field Analyzer II/IIi Introduction to Perimetry
  26. 26. 26 Historical Methodologies of Perimetry Testing Tangent Screen The patient was seated at a distance of 1 meter from the chart. A patch was worn over one eye, and the chart was adjusted so that the eye under test was level with the central fixation point. Wands with colored balls at the end of varying sizes were introduced along a meridian from beyond the patient’s field of vision until the stimulus was seen. A pin was inserted in the chart at that point. Humphrey Field Analyzer II/IIi Introduction to Perimetry
  27. 27. 27 Historical Methodologies of Perimetry Testing Tangent Screen The Tangent Screen was more sophisticated and certainly much more accurate than the Confrontation Test, but it too had its disadvantages: The tester would have to constantly monitor the patient fixation. Relied on ambient light being constant at 7 foot candles The tester had to move the stimulus at a constant speed. Humphrey Field Analyzer II/IIi Introduction to Perimetry
  28. 28. 28 Historical Methodologies of Perimetry Testing Goldmann Perimeter Humphrey Field Analyzer II/IIi Introduction to Perimetry
  29. 29. 29 Historical Methodologies of Perimetry Testing Goldmann Perimeter Although rudimentary in the number of different tests it could perform, and relatively large in size compared to modern day Perimetry equipment, the Goldmann Perimeter set the standards which are still used today for the diagnosis of glaucoma and related diseases of the eye. Humphrey Field Analyzer II/IIi Introduction to Perimetry
  30. 30. 30 A Review of the Anatomy of the Eye Humphrey Field Analyzer II/IIi Introduction to Perimetry
  31. 31. 31 The Conjunctiva is the thin, transparent tissue that covers the outer surface of the eye. It begins at the outer edge of the Cornea, covers the visible portion of the eye, and lines the inner surface of the eyelid. Humphrey Field Analyzer II/IIi Introduction to Perimetry Conjunctiva
  32. 32. 32 Cornea TheThe CorneaCornea is theis the transparent, dome shapedtransparent, dome shaped window which covers thewindow which covers the front of the eye. It is afront of the eye. It is a powerful refractingpowerful refracting surface, providing 2/3 ofsurface, providing 2/3 of the focusing ability of thethe focusing ability of the eye.eye. Humphrey Field Analyzer II/IIi Introduction to Perimetry
  33. 33. 33 Iris TheThe IrisIris is the coloredis the colored portion of the eye. Itportion of the eye. It controls light levels in thecontrols light levels in the eye. It contains muscleseye. It contains muscles which dilate (widen) orwhich dilate (widen) or constrict (narrow) toconstrict (narrow) to control the amount of lightcontrol the amount of light entering the eye. Theentering the eye. The opening at the center isopening at the center is known as theknown as the PupilPupil.. Humphrey Field Analyzer II/IIi Introduction to Perimetry
  34. 34. 34 Pupil The Pupil is the black opening in the center of the Iris. Under the control of the Iris, it opens and closes to control the amount of light which is allowed to enter the eye. PupilPupil Humphrey Field Analyzer II/IIi Introduction to Perimetry
  35. 35. 35 Lens TheThe LensLens providesprovides 1/31/3 ofof the focusing ability of thethe focusing ability of the eye, and serves to focuseye, and serves to focus light entering the eye tolight entering the eye to thethe FoveaFovea. It is suspended. It is suspended in the eye and held inin the eye and held in place by tiny “guy wires”place by tiny “guy wires” calledcalled ZonulesZonules.. Humphrey Field Analyzer II/IIi Introduction to Perimetry
  36. 36. 36 Retina The Retina is a very thin layer of tissue which lines the inner surface of the eye. It functions much like film in photography, capturing the light rays entering the eye. Humphrey Field Analyzer II/IIi Introduction to Perimetry
  37. 37. 37 Macula The Macula is located in the approximate center of the Retina, temporal (towards the temple) to the optic nerve. It is a small and highly sensitive area of the retina responsible for detailed central vision. Humphrey Field Analyzer II/IIi Introduction to Perimetry
  38. 38. 38 Optic Nerve TheThe Optic NerveOptic Nerve transmitstransmits electrical impulses fromelectrical impulses from thethe RetinaRetina to the brain. Itto the brain. It connects to the back ofconnects to the back of the eye near thethe eye near the MaculaMacula.. The visible portion of theThe visible portion of the Optic NerveOptic Nerve is known asis known as thethe Optic DiscOptic Disc.. Humphrey Field Analyzer II/IIi Introduction to Perimetry
  39. 39. 39 Optic Disc The Optic Disc has no sensory receptors. This is the area known as the “blind spot”. Humphrey Field Analyzer II/IIi Introduction to Perimetry
  40. 40. 40 Sclera The Sclera is the tough, opaque tissue known as the “white of the eye”. It serves as the eyes protective outer coat. Humphrey Field Analyzer II/IIi Introduction to Perimetry
  41. 41. 41 Choroid The Choroid lies between the Retina and the Sclera, and is composed of layers of blood vessels which nourish the back of the eye. Humphrey Field Analyzer II/IIi Introduction to Perimetry
  42. 42. 42 Fovea The Fovea is the very center of the Macula and is the most highly sensitive area of the eye. The Fovea also has the highest concentration of RodsRods and CCoonneess Humphrey Field Analyzer II/IIi Introduction to Perimetry
  43. 43. 43 Rod and Cones facts:Rod and Cones facts: The Retina contains approximately 6 million Cones. Cones function best in bright light. Cones help us to appreciate COLOR Cones are most highly concentrated in the Fovea The eye contains approximately 125 million Rods Rods are spread equally throughout the Retina Rods work best in dim light Rods give us our vision.night Humphrey Field Analyzer II/IIi Introduction to Perimetry
  44. 44. 44 The Optic Chiasm The Optic Nerve The Optic Track Optic Track Visual Field Impairments Optic Chiasm Visual Field Impairment Optic Nerve Visual Field Impairment The Human Optical PathThe Human Optical Path Humphrey Field Analyzer II/IIi Introduction to Perimetry Tumors
  45. 45. 45 The Optic Chiasm The Optic Chiasm is located at the base of the brain. Approximately half of the nerves in the Optic Nerve bundle from each eye cross over to the other hemisphere of the brain. As a result, pathologies that develop at the Chiasm, or at the Optic Track, can affect BOTH eyes, while damage to the Optic Nerve will affect only ONE eye. Knowing the nature of visual field issues can help to determine the source of the pathology. Humphrey Field Analyzer II/IIi Introduction to Perimetry
  46. 46. 46 Detection of possible Brain tumor using Field Analysis The example shown below illustrates how Field Analysis tests can be utilized to detect not only visual defects of the eye itself, but also possible brain tumor pathology. Left EyeLeft Eye Right EyeRight Eye Humphrey Field Analyzer II/IIi Introduction to Perimetry
  47. 47. 47 You should now have a basic understanding of the History of Perimetry, the different types of methodologies used in Perimetry testing, and a knowledge of the structure and function of the human eye. In subsequent presentations, you will apply this knowledge to understanding the operation of the Humphrey Field Analyzer HFAII and HFAIIi. Humphrey Field Analyzer II/IIi Introduction to Perimetry
  48. 48. 48 A Simple Field Test On a piece of paper, draw a cross and a dot as below. Hold the paper in your right hand Cover your left Eye Fixate (stare) at the cross While fixating on the cross, pull the paper inward. What happens?   Humphrey Field Analyzer II/IIi Introduction to Perimetry

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