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Verteporfin photodynamic therapy for neovascular age-related ...

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DOI: 10.3310/hta16060Health Technology Assessment 2012; Vol. 16: No. 6153Contrast Sensitivity Testing• Test patients be<strong>for</strong>e adding drugs to the conjunctival sac.• Test CS after logMAR visual acuity testing has been completed.• If the patient was refracted at 2 M add +0.5 D to correction, or if refracted at4M add +0.75 D.• The patient must sit one metre from the chart.• Test the right eye then the left eye.• The eye not being tested must be covered.• Test the right eye with the chart V, R and S as the first triplet.• Test the left eye with the chart that contains H, S and Z as the first triplet.• The charts should remain hidden from view until the eye is ready <strong>for</strong> testing.Recording the patient’s per<strong>for</strong>mance.• Complete the header of the record worksheet.• Ask the patient to name each letter on the chart starting with the dark letterson the upper left-hand corner and reading horizontally across the entire line.• The lighter letters can take some time to appear so ask the patient to keeplooking and not give up too soon• Do not agree or disagree with the patient. You may encour<strong>age</strong> the patient tocontinue to read.• Circle each letter read correctly and cross out each letter read incorrectly.• Leave letters not attempted unmarked.• Test the right eye then the left eye.Do not let the patient give up too soon. Patients should be made to guess even if theybelieve the letters are completely invisible. Always allow several seconds <strong>for</strong> the faintestletters to appear, but do not let the patient give up until he or she has guessed incorrectly 2of 3 letters in a triplet. The reliability of the results depend on the consistency of theexaminer’s approach.Scoring the test. The patient’s sensitivity is indicated by the faintest triplet <strong>for</strong> which 2 of the3 letters are named correctly. The log contrast sensitivity <strong>for</strong> this triplet is given by thenumber on the worksheet nearest to the triplet. Enter this number as the Log ContrastSensitivity Score.© Queen’s Printer and Controller of HMSO 2012. This work was produced by Reeves et al. under the terms of a commissioning contract issued by theSecretary of State <strong>for</strong> Health.

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