Defocus Curve Shift and Effective Addition Defocus curve offers comprehensible information about what is the mean behavior of a multifocal procedure. However, a non-optimal analysis of the obtained data can lead to misinterpretation of the results. In this article, we are going to cover two problems...

Area Under Defocus Curve The Defocus Curve provides a great deal of information that sometimes can be difficult to interpret by looking at the results for each single defocus step. For example, when we measure visual acuity at near (40 cm) we only have one result at a distance but when we measure...

Presentation Distance A frequent question asked is why the Multifocal Lens Analyzer is designed to measure Defocus Curves at 2m or 4m and not at 6m which is considered the standard distance for measuring refraction. To explain the reason it is important to have the following concepts: Changing...

Trial Lenses and Defocus Curve In this article we will explain the lens preparation procedure to be carried out before starting to measure a Defocus Curve, in general with any test, and in particular with the Multifocal Lens Analyzer PRO (MLA). There are three fundamental points that we have to take...

Test Background Brightness Standardization allows reducing the possible bias due to external sources of variation between centers. Using the same test in the same conditions around the world ensures less variation in the global reported clinical results. Background luminance can be a source of bias. We...

Validated Apps for Testing Vision I recently read the manuscript ‘Undermining a common language: Smartphone applications for eye emergencies’, I prepared a Letter to the Editor for clarifying some issues about our Apps for testing vision. Unfortunately, the editor answered that no letters were admitted...