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Lecture Overview

Lecture Overview. Perimetry Definition Visual Field Definition Perimetric Techniques Important Issues in Humphrey Visual Field Analyzer Systemic Interpretation Of Visual Field Printout. What’s Perimetry.

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Lecture Overview

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  1. Lecture Overview • Perimetry Definition • Visual Field Definition • Perimetric Techniques • Important Issues in Humphrey Visual Field Analyzer • Systemic Interpretation Of Visual Field Printout Optom. Rawaa A. El Dous

  2. What’s Perimetry • Is a procedure for measurement of an individual’s visual field; what they are able to see peripherally as well as Centrally. It aims to: • Detection of field defects (screening programs) • Quantitation of the size, shape, and depth of all defects Optom. Rawaa A. El Dous

  3. Now…What's Visual Field? Optom. Rawaa A. El Dous

  4. ≈ 60º Central field Peripheral field ≈60 º 100-110 º 70-75 º Optom. Rawaa A. El Dous

  5. Techniques of perimetry • Kinetic • Static Optom. Rawaa A. El Dous

  6. Techniques of Perimetry • Kinetic - a moving stimulus of fixed intensity and size is moved at a constant rate from non– seeing to seeing regions, identifying points of initial perception. • These points map out an isopter, a defined locus of identical retinal sensitivity. Optom. Rawaa A. El Dous

  7. 0(0.0625 mm² ), I (0.25 mm²), II( 1 mm² ), III (4 mm² ), IV (16 mm²), and V (64 mm² ). Goldman stimulus sizes Optom. Rawaa A. El Dous

  8. isopter Fixation point Optom. Rawaa A. El Dous

  9. Techniques of Perimetry Cont… • Static - a stationary stimulus at a fixed location is gradually increased in intensity or size until the stimulus is initially perceived. • This initial perception determines the retinal threshold sensitivity at that point and the presence and depth of a scotoma may thereby be determined. • Static testing at various points along a meridian defines a profile, or vertical cross-section of the hill of vision Optom. Rawaa A. El Dous

  10. Stimulusintensity Optom. Rawaa A. El Dous

  11. ≈ 60º Horizontal section Point of fixation ≈60 º 100-110 º 70-75 º Vertical section blind spot (Absolute scotoma) Optom. Rawaa A. El Dous

  12. Optom. Rawaa A. El Dous

  13. Automated static perimetry • What does it measure? • How?

  14. Threshold determination Optom. Rawaa A. El Dous

  15. Retinal threshold determination Optom. Rawaa A. El Dous

  16. Strategies • Threshold testing strategies • Full threshold strategy • Faster threshold strategies • Fast threshold strategy • Full from prior data strategy • Swedish interactive threshold algorithm (SITA) • FAST PAC • Screening (suprathreshold) strategies Optom. Rawaa A. El Dous

  17. Full threshold strategy 4/2 dB Optom. Rawaa A. El Dous

  18. Fastthresholdstrategy Optom. Rawaa A. El Dous

  19. Full from prior data strategy Optom. Rawaa A. El Dous

  20. FAST PAC Optom. Rawaa A. El Dous

  21. Swedish interactive threshold algorithm (SITA) • it’s a new strategy that dramatically reduces test time. • It is available as either SITA standard or SITA fast. • The SITA standard test was intended to gather the same information as a full threshold field in much less time. • The SITA strategy is designed to use data in a more intelligent fashion so that less information has to be gathered from the patient. Optom. Rawaa A. El Dous

  22. Swedish interactive threshold algorithm (SITA) • The SITA test calculates expected thresholds and is thus able to begin testing close to the actual threshold. • This strategy uses the patient's age, normal and abnormal databases, and the patient's responses to calculate the expected results for each point. These calculations are constantly updated as more information is gathered. • The SITA strategy employs frequency of seeing curves to shorten the time required to threshold each point. The SITA also customizes the interval between test stimuli to the patient's response time. Optom. Rawaa A. El Dous

  23. Although screening strategies are faster than full threshold strategies, they are generally inadequate for following patients with glaucoma. The simplest strategy, called the "threshold related screening" strategy, tests the point a second time and shows only whether a point is normal or not. A second, more complex, strategy, called the "three-zone screening" strategy, tells whether the defect is relative or absolute by projecting the brightest possible light into the abnormal area. The most complex screening strategy, called a "quantify defects screening" strategy, calculates a threshold on each abnormal point Screening (suprathreshold) strategies (SITA) Optom. Rawaa A. El Dous

  24. Screening (suprathreshold) strategies Optom. Rawaa A. El Dous

  25. Automated Perimeters Optom. Rawaa A. El Dous

  26. Humphrey visual field analyzer Optom. Rawaa A. El Dous

  27. Issues in perimeter design • Stimulus size and intensity • Background illumination • Stimulus duration • Stimulus location and fixation monitoring Optom. Rawaa A. El Dous

  28. STATPAC • STATPAC is a computerized analysis package that is included in the operating system of all Humphrey perimeters. • STATPAC greatly simplifies visual field interpretation by differentiating between normal and abnormal visual fields, and by identifying significant change in a series of visual fields. • STATPAC determines if a patient's visual field results fall within the range normal for his or her age. Optom. Rawaa A. El Dous

  29. STATPAC • A STATPAC analysis may also involve comparing test results with the patient's own baseline from earlier tests in order to determine if the observed change is larger than that typically seen when stable patients return for follow-up testing. • Standard threshold test results may be printed out in any of four formats: • Single Field Analysis • Overview • Glaucoma Change Probability • And Change Analysis Optom. Rawaa A. El Dous

  30. Single visual Field printout Optom. Rawaa A. El Dous

  31. Optom. Rawaa A. El Dous

  32. Systemic interpretation of visual field printout • What type of visual field test was performed? • What are the patient demographics and clinical characteristics? • How reliable is the visual field? • Is the visual field abnormal? • What is the pattern of abnormality? • Is the field worsening? • Is the abnormality or worsening due to disease or artifact? Optom. Rawaa A. El Dous

  33. What type of visual field test was performed? Optom. Rawaa A. El Dous

  34. Systemic interpretation of visual field printout • What type of visual field test was performed? • What are the patient demographics and clinical characteristics? • How reliable is the visual field? • Is the visual field abnormal? • What is the pattern of abnormality? • Is the field worsening? • Is the abnormality or worsening due to disease or artifact? Optom. Rawaa A. El Dous

  35. What are the patient demographics and clinical characteristics? Optom. Rawaa A. El Dous

  36. Systemic interpretation of visual field printout • What type of visual field test was performed? • What are the patient demographics and clinical characteristics? • How reliable is the visual field? • Is the visual field abnormal? • What is the pattern of abnormality? • Is the field worsening? • Is the abnormality or worsening due to disease or artifact? Optom. Rawaa A. El Dous

  37. 3. How reliable is the visual field? Optom. Rawaa A. El Dous

  38. Optom. Rawaa A. El Dous

  39. Optom. Rawaa A. El Dous

  40. Systemic interpretation of visual field printout • What type of visual field test was performed? • What are the patient demographics and clinical characteristics? • How reliable is the visual field? • Is the visual field abnormal? • What is the pattern of abnormality? • Is the field worsening? • Is the abnormality or worsening due to disease or artifact? Optom. Rawaa A. El Dous

  41. Optom. Rawaa A. El Dous

  42. Systemic interpretation of visual field printout • What type of visual field test was performed? • What are the patient demographics and clinical characteristics? • How reliable is the visual field? • Is the visual field abnormal? • What is the pattern of abnormality? • Is the field worsening? • Is the abnormality or worsening due to disease or artifact? Optom. Rawaa A. El Dous

  43. Optom. Rawaa A. El Dous

  44. Glaucoma Hemifield Test Optom. Rawaa A. El Dous

  45. Systemic interpretation of visual field printout • What type of visual field test was performed? • What are the patient demographics and clinical characteristics? • How reliable is the visual field? • Is the visual field abnormal? • What is the pattern of abnormality? • Is the field worsening? • Is the abnormality or worsening due to disease or artifact? Optom. Rawaa A. El Dous

  46. Is the field • worsening? Optom. Rawaa A. El Dous

  47. Systemic Interpretation Of Visual Field Printout • What type of visual field test was performed? • What are the patient demographics and clinical characteristics? • How reliable is the visual field? • Is the visual field abnormal? • What is the pattern of abnormality? • Is the field worsening? • Is the abnormality or worsening due to disease or artifact? Optom. Rawaa A. El Dous

  48. Are the abnormality or worsening due to disease or artifact? Lens rim artifact Optom. Rawaa A. El Dous

  49. Optom. Rawaa A. El Dous

  50. Learning effect After1month After1month Optom. Rawaa A. El Dous

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