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History of perimetry

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    History of perimetry History of perimetry Presentation Transcript

    • Humphrey Field Analyzer II/IIi Introduction to Perimetry
      • 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
      • Additional information may be found in the Field Analyzer User and Service Manuals.
      Humphrey Field Analyzer II/IIi Introduction to Perimetry ?
      • When would a Field test be indicated???
      Humphrey Field Analyzer II/IIi Introduction to Perimetry
      • A Field Test would be indicated for any patient:
      • With an elevated IOP (>21mmHg)
      Humphrey Field Analyzer II/IIi Introduction to Perimetry I ntra O cular P ressure Normal IOP = 12 – 22 mmHg
      • 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
      • A Field Test would be indicated for any patient:
      • With an elevated IOP (>21mmHg)
      Humphrey Field Analyzer II/IIi Introduction to Perimetry
      • 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
      • 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
      • 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
      • 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
    • Humphrey Field Analyzer II/IIi Introduction to Perimetry Boundaries of the Visual Field
      • Normal vision is limited to the following physical limitations:
      • Temporal (towards the temple) – 100 degrees
      • Nasal (towards the nose) – 60 degrees
      • Superior (towards the head) – 60 degrees
      • Inferior (towards the feet) – 75 degrees
    • Humphrey Field Analyzer II/IIi Introduction to Perimetry Normal Boundaries of the Visual Field Temporal 100 degrees Temporal 100 degrees Nasal 60 Degrees Left Eye Right Eye Inferior 75 Degrees Superior 60 degrees Superior 60 degrees Inferior 75 Degrees
    • Humphrey Field Analyzer II/IIi Introduction to Perimetry Normal Boundaries of the Visual Field Both 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 Historical Methodologies of Perimetry Testing Amsler Grid
    • Humphrey Field Analyzer II/IIi Introduction to Perimetry 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:
      • Ensure adequate room lighting.
      • Glasses may be worn.
      • Close one eye and hold the grid at a distance of approximately 14 inches .
    • Humphrey Field Analyzer II/IIi Introduction to Perimetry Historical Methodologies of Perimetry Testing
      • Amsler Grid
      • Fixate on the dot in the center of the grid.
      • Do not allow your gaze to drift from the fixation target.
      • Do any of the lines appear crooked or bent?
      • Do any of the boxes appear different in size or shape from the others?
      • Are any of the lines blurry, wavy, or discolored from the others?
      • If the answers to any of the above were YES , a further examination should be done by a physician. There could be leaking or bleeding of the eye causing pressure on the retina.
    • Humphrey Field Analyzer II/IIi Introduction to Perimetry 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 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 Historical Methodologies of Perimetry Testing Amsler Grid Here are some examples of the types of distortions that patients would report: Scotoma Chorioretinal Scar Arcuate Scotoma Macropsia Micropsia Metamorphasia
    • Humphrey Field Analyzer II/IIi Introduction to Perimetry Historical Methodologies of Perimetry Testing Amsler Grid Patients who experience ANY of these types of distortions should consult with their physician IMMEDIATELY! Scotoma Chorioretinal Scar Arcuate Scotoma Macropsia Micropsia Metamorphasia
    • Humphrey Field Analyzer II/IIi Introduction to Perimetry Historical 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 Historical 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 Historical Methodologies of Perimetry Testing Tangent Screen
    • Humphrey Field Analyzer II/IIi Introduction to Perimetry Historical 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 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 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 Historical Methodologies of Perimetry Testing Goldmann Perimeter
    • Humphrey Field Analyzer II/IIi Introduction to Perimetry 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.
      • A Review of the Anatomy of the Eye
      Humphrey Field Analyzer II/IIi Introduction to Perimetry
    • Humphrey Field Analyzer II/IIi Introduction to Perimetry 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. Conjunctiva
    • Cornea The Cornea is the transparent, dome shaped window which covers the front of the eye. It is a powerful refracting surface, providing 2/3 of the focusing ability of the eye. Humphrey Field Analyzer II/IIi Introduction to Perimetry
    • Iris The Iris is the colored portion of the eye. It controls light levels in the eye. It contains muscles which dilate (widen) or constrict (narrow) to control the amount of light entering the eye. The opening at the center is known as the Pupil . Humphrey Field Analyzer II/IIi Introduction to Perimetry
    • 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. Pupil Humphrey Field Analyzer II/IIi Introduction to Perimetry
    • Lens The Lens provides 1/3 of the focusing ability of the eye, and serves to focus light entering the eye to the Fovea . It is suspended in the eye and held in place by tiny “guy wires” called Zonules . Humphrey Field Analyzer II/IIi Introduction to Perimetry
    • 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
    • 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
    • Optic Nerve The Optic Nerve transmits electrical impulses from the Retina to the brain. It connects to the back of the eye near the Macula . The visible portion of the Optic Nerve is known as the Optic Disc . Humphrey Field Analyzer II/IIi Introduction to Perimetry
    • 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
    • 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
    • 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
    • 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 Rods and C o n e s Humphrey Field Analyzer II/IIi Introduction to Perimetry
      • Rod and Cones facts:
      • The Retina contains approximately 6 million Cones.
      • Cones function best in bright light.
      • Cones help us to appreciate C O L O R
      • 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.
      Humphrey Field Analyzer II/IIi Introduction to Perimetry night
      • The Optic Chiasm
      Humphrey Field Analyzer II/IIi Introduction to Perimetry The Optic Nerve The Optic Track Optic Track Visual Field Impairments Optic Chiasm Visual Field Impairment Optic Nerve Visual Field Impairment The Human Optical Path Tumors
      • The Optic Chiasm
      Humphrey Field Analyzer II/IIi Introduction to Perimetry 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.
      • Detection of possible Brain tumor using Field Analysis
      Humphrey Field Analyzer II/IIi Introduction to Perimetry 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 Eye Right Eye
      • 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
      • 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  