The Visual Field - For Doctors

3,470 views

Published on

Published in: Health & Medicine
0 Comments
5 Likes
Statistics
Notes
  • Be the first to comment

No Downloads
Views
Total views
3,470
On SlideShare
0
From Embeds
0
Number of Embeds
478
Actions
Shares
0
Downloads
284
Comments
0
Likes
5
Embeds 0
No embeds

No notes for slide

The Visual Field - For Doctors

  1. 1. Dwight Thibodeaux, OD THE VISUAL FIELD
  2. 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. 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. 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 Ocotopus Oculus and others
  5. 5. HISTORICAL FIELD TESTS
  6. 6. CONFRONTATION FIELD TESTING Technique Targets
  7. 7. GOLDMANN KINETIC FIELD TESTER
  8. 8. GOLDMANN KINETIC PERIMETRY
  9. 9. OCTOPUS AND OCULUS
  10. 10. ZEISS/HUMPHRIES HUMPHRIES FIELD ANALYZER (HFA) FDT and MATRIX
  11. 11. SUPRATHRESHOLD • Targets set at moderate brightness with wide field • Either seen or not seen • Useful for lid/ptosis evaluation • Two field tests, taped and untaped
  12. 12. THRESHOLDING • First stimuli 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
  13. 13. SITA / SITA FAST (HFA) Swedish Interactive Thresholding Algorithm SITA 50% faster than standard, but 90% accuracy SITA FAST 70% faster, 80% as accurate
  14. 14. FDT/FDP • Frequency Doubling Technology (Perimetry) • Grating target flickered quickly creates and illusion of a doubled grating, stimulating a different neuro pathway • For early detection of glaucoma • Resistant to blur (Rx) and pupil size effects
  15. 15. 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
  16. 16. 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
  17. 17. 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
  18. 18. HFA 10-2 • Central field testing • Most commonly used for patients with risk for macular toxicity • Plaquenil – hydroxychloroquine used chiefly for rheumatoid arthritis • OCT of macula also part of new protocol
  19. 19. MICROPERIMETRY • Amsler Grid • Automated
  20. 20. WHEN TO USE WHAT • Glaucoma suspect or pre-perimetric pt. • Established glaucoma patient with field loss • Neuro patient • Ptosis patient • High risk meds patient
  21. 21. 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
  22. 22. ESTABLISHED GLAUCOMA • SITA Standard 30-2 • Difficult / older patient SITA Fast 24-2
  23. 23. NEURO FIELDS • SITA Fast 30-2 • Matrix oversensitive
  24. 24. PTOSIS OR BLEPHAROCHALASIS • Suprathreshold automated or kinetic fields • Wider field to catch more peripheral defects • Don’t need thresholding
  25. 25. HIGH RISK MEDS • SITA 10-2 • For subtle central defects from retinal toxicity • Used in conjunction with SD-OCT for Plaquenil (hydroxychloroquine) screening
  26. 26. QUALITY MEASURES • Fixation losses – targets blind spot, need <15%, use gaze tracker for confirmation, ? misaligned • False positives – notes positive response when no target is shown < 20% or not a reliable study • False negatives – notes lack of response in area previously seen at lower illumination <33% • Gaze tracker - camera notes eye
  27. 27. DATA ANALYSIS
  28. 28. 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
  29. 29. DATA ANALYSIS • Grey scale • Threshold values in Db • Variance from normal threshold in Db • Mean Deviation (MD) • Positive Standard Deviation (PSD) • Glaucoma Hemifield Test (GHT)
  30. 30. GREY SCALE / THRESHOLD VALUES • Quickly identifies overall depressions • Good for patient education • Shows thresholds for each spot tested in Db • No comparison for age related normals • No adjustment for media opacities • Under represents shallow gen. depression and overemphasizes midperipheral non- significant defects
  31. 31. TOTAL DEVIATION PLOT • Graph and numeric representation • Compared to age-matched normals
  32. 32. PATTERN DEVIATION PLOT • Probably the most important data • Takes total deviation and filters out overall depression • Looks for focal damaged areas pertinent to glaucoma
  33. 33. GLAUCOMA HEMIFIELD TEST - GHT • Compares top and bottom half of field • General reduction in sensitivity • Abnormally high sensitivity • Outside Normal Limits – difference not found in 99% of patients without glaucoma • Borderline – difference not found in 97% of normals
  34. 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. 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. 36. 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
  37. 37. PATTERN STANDARD DEVIATION (PSD) • Sensitive measurement of localized loss • Especially useful in glaucoma evaluation/progression • The higher the number, the greater the loss
  38. 38. COMMON GLAUCOMA DEFECTS (SCOTOMAS) • Arcuate • Nasal step • Temporal wedge • Localized paracentral • Generalized depression • Compare to clinical picture – know what to expect
  39. 39. ARCUATE OR NERVE FIBER BUNDLE DEFECT
  40. 40. NASAL STEP
  41. 41. LOCALIZED PARACENTRAL SCOTOMAS
  42. 42. SECTOR OR WEDGE DEFECTS
  43. 43. GENERALIZED DEPRESSION
  44. 44. 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
  45. 45. HOMONYMOUS • Hemianopsia – right homonymous, congruous, points to cortical lesion such as stroke • Quadranopsia or sectoranopsia– cerebral (congruous) or lateral geniculate nucleus
  46. 46. HETERONOMOUS Hemianopsia- bitemporal, congruous— points to chaismal lesion such as a pituitary tumor Quadranopsia- very rare, also points to area of chaism
  47. 47. ALTITUDINAL • Almost always unilateral • Associated with AION – stroke at the optic disc
  48. 48. CENTRAL SCOTOMA • More commonly unilateral as in: optic neuritis macular degeneration early AION retinal dystrophy Bilateral – toxic, nutritional, heriditary optic neuropathy and maculopathy
  49. 49. QUESTIONS? DRTHIB@MSN.COM

×