Visual Field Review

1. Visual Field Review Kelli Shaon, O.D.

2. Interpretation of the Visual Field • What type of VF was performed? • What are patient demographics & clinical characteristics ? • Name, DOB, Date of VF, Patient ID, Pupil diameter, • Corrective lenses used • Time it tool to complete the test • How reliable is the field? • Is the VF abnormal? • What is the pattern of abnormality? • Is the field worsening? • Is the abnormality or worsening due to disease or artifact? Budenz, D. Atlas of visual Fields. 1997.

3. What does everything mean??? • Fixation losses – estimate of the # of times the pt fails to look at the central fixation target • It is determined by plotting the blind spot, then later presenting a target into spot (pt should NOT respond) • What 2 ways can the Fixation loss be high? • False positives – the # of times a patient responds to a stimulus that is NOT presented • High false positive results indicate a “trigger happy” pt. • Big indicator in the test being UNRELIABLE • False negatives – Suprathreshold targets are presented in areas already determined to be sensitive to lesser targets, and patients fail to respond • Reasons for high FN = inattentive (poor fixation), fatigue, or malingering • May present with an artificially poor VF

4. What does everything mean??? • Short-term fluctuations – measure of normal variation & intra test reliability • The VF analyzer pres-selects different points to re-test (during the VF) to compare the fluctuation in response • Threshold printout – raw data of the sensitivity of the retina at the various tested locations (in dB) • The higher the dB, the dimmer the stimulus • The lower the dB, the brighter the stimulus • If it is 0, then patient could not see brightest stimulus • Foveal threshold – Foveal sensitivity (measured at the beginning of the test) • If significantly decreased, often due to disease process (ie. Media, retina, ON)

5. What does everything mean??? • Graytone printout – shows overall depression patterns. • Total deviation & Probability plot – Most useful in telling if a VF is abnormal • The numbered chart is the difference b/w the pt’s threshold values & those of aged matched normals • Pattern deviation & Probability plot – most important for determining a localized abnormality • Derived from the total deviation plot, then subtracts out the diffuse depression • The numbered chart is the difference b/w the pt’s threshold values & those of aged matched normals after taking into account the diffuse depression

6. What does everything mean??? • Mean deviation – the average difference between the pt’s overall sensitivity & those of age-matched normals • Negative value = below average • Positive value = above average • Glaucoma Hemifield test (GHT) – comparison of 5 zones in the upper & lower hemifields – to identify if differences between the two hemifields • Corrected Pattern Standard Deviation – measure the degree of localized depression (not the overall depression) based on Short-term fluctuation & the patient’s age. • The higher the CPSD the more likely it is to have an area of localized depression. • The higher the SF, the lower the CPSD Budenz, D. Atlas of visual Fields. 1997.

7. Did you know, you can classify Glaucoma VF defects? • Criteria for Minimal Abnormality in Glaucoma • Three or more adjacent points in an expected location of the central 24º field (Must be nonedge points in the central 30 º field) that have P <5% on the pattern deviation plot, one of which must have P < 1% • Glaucoma hemifield test “outside normal limits” • Corrected Pattern standard deviation with P < 5%

8. How to classify Glaucoma VF defects • Criteria for Early Defect in Glaucoma • Mean deviation no worse than -6 dB • On pattern deviation plot, fewer than 25% of points depressed below 5% level and fewer than 15% of points depressed below 1% level • No point within the central 5 º with sensitivity less than 15 dB

9. How to classify Glaucoma VF defects • Criteria for Moderate Defect in Glaucoma • Mean deviation worse than 6 dB but no worse than -12 dB • On pattern deviation plot, fewer than 50% of points depressed below the 5% level and fewer than 25% of points depressed below 1% level • No point within central 5 º with sensitivity less than or equal to 0 dB • Only 1 hemifield containing a point with sensitivity less than 15 dB within 5 º of fixation

10. How to classify Glaucoma VF defects • Criteria for Severe Defect in Glaucoma • Mean deviation worse than -12 dB • On pattern deviation plot, more than 50% of points depressed below the 5% level and more than 25% of points depressed below 1% level • Any point within central 5 º with sensitivity less than or equal to 0 dB • Both hemifields containing a point(s) with sensitivity less than 15 dB within 5 º of fixation Hodapp, E. et al. Clinical decisions in Glaucoma. 1993

11. Visual Field: Case #1

12. Visual Field: Case #1 • How is the reliability? • Describe the field. • What findings do you expect to find on ocular examination? • Will they have an APD? • Is this caused by glaucoma? If so, how would you classify it?

13. Visual Field: Case #2

14. Visual Field: Case #2 • How is the reliability? • Describe the field. • What findings do you expect to find on ocular examination? • Will they have an APD? • Is this caused by glaucoma? If so, how would you classify it?

15. Visual Field: Case #3

16. Visual Field: Case #3 • How is the reliability? • Describe the field. • What findings do you expect to find on ocular examination? • Will they have an APD? • Is this caused by glaucoma? If so, how would you classify it?

17. Visual Field: Case #4

18. Visual Field: Case #4 • How is the reliability? • Describe the field. • What findings do you expect to find on ocular examination? • Will they have an APD? • Is this caused by glaucoma? If so, how would you classify it?

19. Visual Field: Case #5

20. Visual Field: Case #5 • How is the reliability? • Describe the field. • What findings do you expect to find on ocular examination? • Will they have an APD? • How are these fields different?

21. Visual Field: Case #6

22. Visual Field: Case #6 • How is the reliability? • Describe the field. • What findings do you expect to find on ocular examination? • Will they have an APD?

23. Visual Field: Case #7

24. Visual Field: Case #7 • How is the reliability? • Describe the field. • What findings do you expect to find on ocular examination? • Will they have an APD?

25. Where is the lesion? Does this VF defect have a specific name? Visual Field: Case #8

26. Visual Field: Case #9 • What is this called? • When would you get this lesion? • How should you handle this case?

27. Visual field Defects • When would you get A? • When would you get B? • When would you get C?

28. Review facts…… • Questions to ask yourself • Is it reliable? • If not, why? • Is it unilateral or bilateral • Is it a problem of the ON/retina or visual pathway? • What are you looking for on the examination? • Things to remember • Gross defects will often still show up on the VF even if it is NOT reliable • Even the most experienced VF interpreter will get stumped from time to time • Always ask for someone else’s opinion if your not sure