CSFO Amsler Chart 2023-24 Slides PDF

The Amsler Chart Dr Sheila Rae CSFO1 2023-24 1 Amsler chart Introduced in 1945 to assess macular function Is a form of static visual field test with simultaneous viewing if the stimulus across the tested area Assesses a grid 10 degrees either side of fixation Grid...

The Amsler Chart Dr Sheila Rae CSFO1 2023-24 1 Amsler chart Introduced in 1945 to assess macular function Is a form of static visual field test with simultaneous viewing if the stimulus across the tested area Assesses a grid 10 degrees either side of fixation Grid pattern useful for detecting metamorphopsia (distortion) in the macular area Also shows areas of scotoma Comes as a book with a series of plates Separate recording sheets or sheets for Px to self monitor 2 Amsler charts 2 to 7 3 Amsler charts: when to use Unexplained reduced visual acuity Symptoms of distortion Signs of age-related macular degeneration Patients on certain medications known to affect the macula Chloroquine or hydroxychloroquine, usually used to treat auto-immune disorders Tamoxifen Must test MONCULARLY 4 Amsler charts 1&2 Chart 1 most commonly used Detects scotomas and metamorphopsia Each square subtends 10 of the visual field Chart 2 has added diagonal lines to aid fixation and localisation of defects Especially useful with central scotoma as can ask Px to fixate where the diagonal lines would cross 5 Use in preference to chart 1 Amsler charts 3&4 Chart 3 is a red on black version of chart 1 To enhance detection of certain pathologies Toxic maculopathy due to drugs Optic nerve disorders Chart 4 has a random dot pattern Metamorphopsia won’t affect the pattern as is random Scotomas will still show up 6 Amsler charts 5, 6, 7 Chart 5 reveals metamorphopsia along specific meridians Can be turned so that lines are vertical Chart 6 is similar in reversed contrast with closer spacing in central 2 degrees for subtle changes Chart 7 smaller central squares Detects subtle defects 7 Amsler technique Explain the reason for the test to the patient Ask patient to wear their near correction if any Occlude one eye Always test MONOCULARLY Hold the Amsler at 28-30cm – measure this! Incorrect distance means not measuring central 10 degrees Ensure that the chart is evenly illuminated and that the lighting is good 8 Amsler technique Using the main chart Ask the patient to look at the central dot if they cannot see it move onto chart No 2 Ask While you are looking at the central dot can you see all four corners of the square? While you are looking at the central dot are the straight lines straight or do any waver or bend? While you are looking at the central dot are there any areas of the grid missing? 9 Recording Results Ask the patient to draw what they see on the recording charts LE Older patients might need to describe defects so that you can draw it Do not use the recording charts in place of the Amsler chart Always use the ‘white on black’ versions Record the eye and add a description 10 Results: variety of appearances may be described 12 Amsler results Left shows how an optom would record the patient’s description 13 Amsler Limitations Sensitivity 9% in early AMD 34% in choroidal neovascularisation Low sensitivity means high false negative rate People who have the condition are missed Replaced by OCT but useful to issue paper version for px to test weekly Self monitor for changes in appearance 14