Fitting Guidelines - David Thomas Contact Lenses

C2MULTIFOCALFitting GuidelinesPre-Fit ExaminationHave a recent distance vision refraction (maximum convex)Near Vision Addition = Minimum Addition + 1.00 D*Distance Vision Binocular Refraction• Make patient read the near vision test at 40 cm distance• Progressively add binocular lenses in +0.25D stepsuntil patient is able to read 0.8 paragraph in the test.Looking for the dominant eye :In binocular distance vision, patient wearing his distance vision correction :• Place alternately in front of each eye a trial lens +0.75D• The most reluctant eye in distance vision will be the preferred one tocorrect distance vision.Choice of the First LensDistance Vision Power : Use refraction (maximum convex) taking vertexdistance into accountAddition : ≤ 1.75 Low Add> 1.75 High AddGeometryFront Surface : AsphericBack Surface : Spherical AsphericBase Curve8.60 mmDiameter14.20 mmPowers-6.00 to +6.00 in 0.25D steps-6.50 to -8.00 in 0.50D stepsAdditionsLow ≤ +1.75High > +1.75Center Thickness (@ -3.00 D) 0.07 mmWater Content 58%Dk 60Dk/t 86Modulus0.50 MPaReplacementMonthly

C2MULTIFOCALCheck Fit and VisionCentrationMovementCheck Visual Acuity : Binocular Near and Distance VisionOptimizing Distance Vision (if required)If LOW Add profileTry -0.25 / -0.50on the dominant eye in DVIf HIGH Add profileFit LOW Addon the dominant eye in DVCheck Near VisionOptimizing Near Vision (if required)If LOW Add profileFit HIGH Addon the dominant eye in NVIf HIGH Add profileTry +0.25 / +0.50on the dominant eye in NVCheck Distance VisionDavid Thomas Contact Lenses Ltd, Gatelodge Close,Round Spinney, Northampton NN3 8RJ.Tel: +44 (0) 1604 646216 Fax: +44 (0) 1604 790366Email: enquiries@davidthomas.com Web: www.davidthomas.com