The Visual Field for Technicians
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The Visual Field for Technicians

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Visual Field for Technicians.

Visual Field for Technicians.

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The Visual Field for Technicians Presentation Transcript

  • 1. Dwight Thibodeaux, OD THE VISUAL FIELD
  • 2. VISUAL FIELDS Localized measurement of visual perception using manual or automated methods to determine normal status or to evaluate and track an ocular or neurological disease state.
  • 3. NORMAL FIELDS • Visual Field - Roughly 140 degrees monocularly and just over 180 degrees binocularly • Field of Gaze – Over 200 deg • Field of View – Over
  • 4. COMMON METHODS OF FIELDS TESTING • Confrontation –gross target movement - in from periphery • Manual kinetic central fields – Tangent screen, Autoplot • Microperimetry – Amsler Grid, automated units • Manual kinetic widefield perimetry – Goldmann • Automated static perimetry – Computer algorithm, tester independent Humphries HFA and FDT/Matrix Haag-Streit Octopus Oculus and others
  • 5. HISTORICAL FIELD TESTS
  • 6. CONFRONTATION FIELD TESTING Technique Targets
  • 7. GOLDMANN KINETIC FIELD TESTER
  • 8. GOLDMANN KINETIC PERIMETRY
  • 9. OCTOPUS AND OCULUS
  • 10. ZEISS/HUMPHRIES HUMPHRIES FIELD ANALYZER (HFA) FDT and MATRIX
  • 11. TEST STRATEGIES • Suprathreshold – usually full field - 60 degrees • 24 degree central field 24-2 • 30 degree central 30-2 • 10 degree 10-2
  • 12. SUPRATHRESHOLD • Targets set at moderate brightness (above threshold) with wide field • Either seen or not seen • Useful for lid/ptosis evaluation • Two field tests, taped and untaped
  • 13. THRESHOLDING • First stimuli presented in each of the 4 quadrants • Lowered by 3-4 Db until not seen and vise versa • Moves to different area and repeats process • Cloverleaf pattern in poor pt. management and cooperation
  • 14. SITA / SITA FAST (HFA) Swedish Interactive Thresholding Algorithm SITA 50% faster than standard, but 90% accuracy SITA FAST 70% faster, 80% as accurate
  • 15. FDT/FDP • Frequency Doubling Technology (Perimetry) • For early detection of glaucoma • Resistant to blur (Rx) and pupil size effects
  • 16. MATRIX FDT • Hybrid of FDT and SAP • Even more sensitive to early glaucoma defects • Too hypersensitive for neuro field testing and poor for tracking glaucoma progression • Best for glaucoma suspects / pre-perimetric glaucoma
  • 17. SWAP – SHORT WAVELENGTH AUTO PERIMETRY • Yellow background and large blue stimulus on HFA • Catches early defects in pre-perimetric glaucoma • Very time consuming and sensitive to media opacities • Matrix now more commonly used
  • 18. 30-2 VS 24-2 • 30-2 = 76 test locations Most accurate, 0.2 sec. stimulus vs. 0.25 sec latency for eye movements • 24-2 = 54 test locations Used for the difficult patient
  • 19. HFA 10-2 • 10 deg. central field for macular toxicity and end stage glaucoma or RP • Plaquenil – hydroxychloroqui ne • OCT of macula also part of new protocol
  • 20. MICROPERIMETRY • Amsler Grid • Automated
  • 21. WHAT FIELD IS INDICATED? • Glaucoma suspect or pre-perimetric pt. • Established glaucoma patient with field loss • Neuro patient • Ptosis patient • High risk meds patient
  • 22. GLAUCOMA SUSPECT • Minimal or no nerve head cupping – Matrix/FDT • Obvious nerve damage – SITA Standard 30-2 • Difficult patient w/ damage– SITA Fast 24-2
  • 23. ESTABLISHED GLAUCOMA • SITA Standard 30-2 • Difficult / older patient SITA Fast 24-2
  • 24. NEURO FIELDS • SITA Fast 30-2 • Used for unexplained vision loss or neuro signs • Matrix oversensitive
  • 25. PTOSIS OR BLEPHAROCHALASIS • Suprathreshold automated or kinetic fields • Wider field to catch more peripheral defects
  • 26. HIGH RISK MEDS SITA 10-2 • For subtle central defects from retinal toxicity
  • 27. INTERPRETATION • Quality measures and errors • Plots • Glaucoma Hemifield Test • Global indices
  • 28. QUALITY MEASURES • Fixation losses – targets blind spot, need <15%, ? misaligned • False positives – positive response when no target is shown, need < 20% • False negatives – <33% • Gaze tracker - camera notes eye movement
  • 29. COMMON ARTIFACTS AND ERRORS • Ptosis • Prominent brows • Lens holder positioning—ring scotoma • Patient positioning—high FL, ring scotoma • False positives based on patient expectations of stimulus timing
  • 30. GREY SCALE PLOT • Quickly identifies overall depressions • Good for patient education • No comparison for age related normals • No adjustment for media opacities • Under represents shallow gen. depression and overemphasizes midperipheral non- significant defects
  • 31. TOTAL DEVIATION PLOT • Graph and numeric representation • Compared to age-matched normals
  • 32. PATTERN DEVIATION PLOT • Probably the most important data • Takes total deviation and filters out overall depression (cataracts) • Looks for focal damaged areas pertinent to glaucoma
  • 33. GLOBAL INDICES • Mean Deviation (MD) • Positive Standard Deviation (PSD) • Glaucoma Hemifield Test (GHT)
  • 34. GLOBAL INDICES • Single number representations of the visual field • Overall guidelines to help assess the field • Probability values when numbers reach significant levels
  • 35. MEAN DEVIATION (MD) • Overall level of sensitivity compared to age-matched normals • Not corrected for generalized depression from media opacities • Important for following diffuse loss in glaucoma • MD of -2.00 or worse is suspicious • Mild damage at <-6 • Moderate at -6 to-12 severe >-12
  • 36. PATTERN STANDARD DEVIATION (PSD) • Sensitive measurement of localized loss • Especially useful in glaucoma evaluation/progression • The higher the number, the greater the loss
  • 37. GLAUCOMA HEMIFIELD TEST GHT • Compares top and bottom half of field • General reduction in sensitivity • Abnormally high sensitivity • ONL – difference not found in 99% of patients without glaucoma • Borderline – difference not found in 97% of normals
  • 38. VISUAL FUNCTION INDEX (VFI) AND PROGRESSION ANALYSIS Seen in newer units VFI similar in meaning to MD but easier to conceptualize-- 100% is normal 75-80% is approaching significant loss = -6 or worse on MD
  • 39. COMMON GLAUCOMA SCOTOMAS • Arcuate • Nasal step • Temporal wedge • Localized paracentral • Generalized depression
  • 40. ARCUATE OR NERVE FIBER BUNDLE DEFECT
  • 41. NASAL STEP
  • 42. LOCALIZED PARACENTRAL SCOTOMAS
  • 43. SECTOR OR WEDGE DEFECTS
  • 44. GENERALIZED DEPRESSION
  • 45. FUNCTIONAL VISION LOSS • Most common in young girls • Emotional trauma • Also called hysterical fields • Spiral and variable in nature • Treat with education of parents and counseling
  • 46. NEURO FIELDS Unilateral – usually involves the retina or optic nerve Bilateral – involves both nerves or the optic chiasm/tract/brain Homonymous – alike, same side on both eyes Heteronomous – different, opposite sides Congruous – symmetric in both eyes Hemianopia – defect respects vertical midline
  • 47. MRI CHIASM
  • 48. HOMONYMOUS • Hemianopsia – homonymous, congruous, points to cerebral cortex lesion such as stroke • Quadranopsia or sectoranopsia– cerebral cortex (congruous) or lateral geniculate nucleus
  • 49. HETERONOMOUS Hemianopsia- bitemporal, congruous- points to chiasmal lesion such as a pituitary tumor Quadranopsia- very rare, points to different area of chiasm
  • 50. BINOCULAR FIELDS
  • 51. ALTITUDINAL • Almost always unilateral • Associated with AION – stroke at the optic disc
  • 52. CENTRAL SCOTOMA • More commonly unilateral as in: optic neuritis macular degeneration early AION, cerebro-vascular blood loss retinal dystrophy Bilateral – toxic, nutritional, heriditary optic neuropathy and maculopathy
  • 53. QUESTIONS? DRTHIB@MSN.COM