AMSLER CHARTS.pptx

A presentation on the history and well defined description on amsler chart, along with the various types of amsler chart and its uses, advantages, disadvantages and limitation. The procedure of performing the test and the sequences of question asked during the test is also well elaborated.

1. AMSLER CHARTS Presented By- Name- Abhishek Kashyap B.Optom 3 rd year Ridley college of optometry

2. Layouts History Introduction Types Procedures Advantages, disadvantages and limitation Interpretation

3. History In 1920s, Marc Amsler, a swiss ophthalmologist, designed the amsler grid

4. Introduction The Amsler Grid is a rapid, qualitative technique designed to test central 20 ̊of the visual field It comprises of seven charts All charts are in a shape of square, covering an area of 100cm² (10cm x 10cm)

5. Each square of the grid is 5mm, subtending approximately 1 ̊ at 30 cm It is a diagnostic tool that is used mainly in screening, detection and monitoring macular diseases as well as optic nerve and visual pathway lesions

6. Types Chart 1: The most familiar and widely used chart It comprises a high contrast white grid against the black background with a central fixation point It enables in identification of various forms of distortion as well as relative scotomas

7. Chart 2: Similar to chart 1 with two additional diagonal white lines crossing through the central fixation spot It is use for patients having a central scotoma

8. Chart 3: Similar to chart 1 but with red grid It is used in the evaluation of color scotoma and desaturation which occurs in toxic maculopathy, optic neuropathy, chiasmal lesion It is also aid in the identification of malingering patients when used in conjuction with red and green filter

9. Chart 4: It displays a series of random white dot against the black background Its soul purpose is in detection of scotoma

10. Chart 5: It consist of 20 evenly spaced white parallel lines against the black background The chart can be rotated to change the orientation of the lines And is used to investigate metamorphopsia along specific meridians

11. Chart 6: Similar to chart 5 but has black lines against the white background This chart has additional lines with half the spacing in central 2 ̊ area, subtending a small angle of 0.5 ̊ at the eye So, it enable more detail examination

12. Chart 7: Similar to chart 1 but contains additional square of 0.5 ̊ subtends in central 8 ̊ x 6 ̊ area So, it provide a more sensitive assessment of the macula

13. Modified Amsler Charts Yannuzzi Card Diamond Chart Transilluminated Grid Yannuzzi Card

14. Procedure First, the patient is asked to seat comfortably with the appropriate near correction As the working distance for the test is 30 cm, a +3.25 D near add should be used for absolute presbyopes or the patient’s own spectacles are usually satisfactory Use a single vision glasses or trial lenses, but avoid bifocal and multifocal lenses

15. The examiner should position such that he/she could be able to occlude the non-viewing eye and measure the working distance Keep the room light well- illuminated Now, the patient is asked to look at the central dot of the chart at all the time with right eye and occluding the left eye

16. Patient is instructed to show on the chart if he/she notices any missing and distorted area/ lines Repeat the same procedure for left eye occluding the right eye

17. Sequences of questions Can you see the central white dot? Keeping the gaze fixed on the white dot, can you see the four corners/sides of the squares? Are any of the small squares blurry or missing on any part of the grid? Do any of the horizontal or vertical lines that make up the squares appear wavy or bent?

18. 5. Is any part of the grid shimmering, flickering, or colored?

19. Advantages Rapid test Cheap Portable Easy to use

20. Disadvantages Can assess only 20 ̊ of the visual field area Complete subjective test

21. Limitation Completion phenomenon Use of high contrast well illuminated grid against which relative scotoma can easily be missed Patient with well established central scotoma can adapt to this defect by fixating eccentrically when viewing the chart, thereby giving rise to apparent paracentral scotoma

22. 4) Chart 3 provide poor contrast, which make the chart difficult to see, giving rise to a high level of false positive response

23. Interpretation

24. Reference Primary care Optometry, 4 th edition, by Theodore Grosvenor, page no.  155-156 Clinical procedures in optometry, page no. 436- 446