## Advanced Analysis of Defocus Curve Results

Summary: Defocus curve offers comprehensive 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 in the statistical analysis of defocus curves.
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...

## The Area Under the Defocus Curve with MLA

Summary: 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 a defocus curve we can have, if we go from -2.00 to -4.00 D in 0.50 D steps, up to 5 values that describe visual performance at near from 50 cm to 25 cm. How do we take advantage of all this information to draw conclusions about visual performance at near?
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...

## Why do we measure the defocus curves at 2 m or 4 m and not at 6 m?

Summary: 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.
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...

## Preparing the lenses to measure a Defocus Curve

Summary: 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).
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...

## The Role of Background Brightness in the Measurement of Visual Performance with Multifocal Procedures

Summary: 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 review why using an iPad could reduce the variability in clinical research.
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

Summary: 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 after one month of publication of the original source. Therefore, we decided to publish the letter here.
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...