AMSLER CHARTS - Definition, types, usess

This presentation includes all about amsler chart which is an optometry equipment to determine central visual field of an individual. It's definition, uses, types, advantages, disadvantages and the limitations

1. AMSLER CHARTS Presented by : Florina Deka B.Optom 2nd year , RCOJ

2. INTRODUCTION The amsler grid is a rapid, qualitative technique to test central 20° of the visual field It helps delineates any central or centrocecal scotoma in the visual field It comprises of 7 charts All charts are in a shape of square, covering an area of 100cm square ( 10cm x 10cm ) 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

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

4. PROCEDURE First the patient is asked to seat comfortably with appropriate near correction As the working distance for the test is 30cm, a +3.25D near add should be used for absolute presbyopes or patient’s own spectacles are satisfactory Use a single vision glasses or trial lenses, but avoid bifocal or multifocal lenses The examiner should position such that he/she could be able to occlude the non viewing eye and measure the working distance

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

6. QUESTIONS TO BE ASKED Is the central dot visible ? While looking at the central dot, are the four corners of the square visible ? Are any squares missing ? If yes ask the patient to marked out the scotoma Are any lines wavy or distorted? If yes, ask the patient to marked them out

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

8. CHART 2 Similar to chart 1 with addition of 2 diagonals lines crossing through the central fixation spot Use for patients with central scotoma

9. CHART 3 Similar to chart 1 but with red grid Used in the evaluation of color scotomas and desaturation which occurs in toxic maculopathy , optic neuropathy and chiasmal lession It is also aid in identification of malingering patients when used in conjunction with red and green filter

10. CHART 4 It displace a series of random white dots against a black background Its soul purpose is to evaluate scotomas Subsequently, its main use as a Clinical aid is to distinguish Scotomas from metamorphopsia

11. CHART 5 It consist of a series of horizontal white lines against the black background The chart can be rotated to change the orientation of the lines It is design to map matamorphopsia in specific horizontal and vertical meridians

12. CHART 6 Similar to chart 5 but has additional lines with half the spacing in the central 2 ° area , subtending a small angle of 0.5 degree at the eye So it enable more detailed examination

13. CHART 7 Similar to chart 1 but contains additional square of 0.5 ° subtends in central 8 ° x 6 ° area S o , it provide a more sensitive assessment of the macula

14. ADVANTAGES Easy Cheap Portable Rapid test

15. DISADVANTAGES Can assess only 20 ° of the central visual field Completely subjective test

16. LIMITATIONS Use of high contrast well illuminated grid against which relative scotoma can be easily 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 Chart 3 provide very poor contrast, which make the chart difficult to see, giving rise to a high level of false positive response

17. REFERENCE Primary care optometry, 4 th edition by Theodore Grosvenor, (page no. 155 – 156) Clinical procedure in optometry, (page no. 436 – 446)

18. THANK YOU