MultifocalLA

The testing defocus curve of a patient typically involves setting up the trial lens at a viewing distance that promotes accurate refraction. Generally, the test is placed from 4 to 6 meters away from the patient to establish a far distance. However, this distance not always can be adjusted for matching the measurement of visual acuity at Infinity (0 D). Thus, the recommendation is always to measure the defocus curve with a multifocal IOL at a distance of 4 m with the best distance refraction obtained at 4 meters.

The defocus curve is a vital part of visual performance testing, especially after refractive surgery such as cataract surgery where an intraocular lens, like an edof iol, bifocal iol, trifocal iol, monofocal iol, or a mix & match procedure with different lens in the non-dominant or dominant eye is inserted. The measure of defocus curve is typically conducted between 4 m and 6 m. Considering that the far point of the emmetropic patient is at infinity when we approach the test at 6 m, we are inducing a myopia of -0.1667 D. In other words, a patient refracted at 6 m and from whose refraction we obtain 0 D, may not really be emmetropic but myopic of -0.1667 D (1/-6). This is generally not clinically relevant because we measure the refraction in steps of 0.25 D or even the depth of focus might compensate for this small error. If 4 m are not available for testing the defocus curve, the next possible option is to measure the defocus curve at 2 m because it is the next step we can correct with an spherical lens of +0.50 D to move the infinity refraction focus to a 2 m of distance. Take notice that 3 m would be +0.33 D and again we do not use spherical lens to exactly correct +0.33 D. Anyway, if it is possible always refract and measure at 4 m.

When looking at a defocus curve as a clinician or an industry professional, there are several key things to consider. You should look at the overall shape of the defocus curve, whether there are any unusual or unexpected results, and how the curve relates to the lens performance, including vision at different distances, such as near or intermediate vision. It is essential to take into account the patient's visual acuity, any potential visual disturbances, and any applicable lens specifications, such as the diopter of a monofocal iol or a bifocal iol. These factors will give a fuller picture of the patient's vision and how it may be affected by the lens and any potential corneal astigmatism.

Defocus curve testing results could potentially change the focus of research and clinical practice in several ways. They could lead to advancements in intraocular lens designs, like the edof iol, bifocal iol, or trifocal iol, to further improve visual acuity, particularly in the area of extended depth of focus intraocular lens. These results might also highlight the need for a fast measure in the examination process or the importance of correcting spherical aberration. Furthermore, they could impact cataract surgery practices, influencing the choice of lens and the approach towards managing patient expectations.

Defocus curves are known to be a reliable method of assessing visual performance and visual acuity. They provide information about the quality of vision across different distances - from far distance to intermediate distance - and how it varies with different amounts of defocus. The use of defocus curves is particularly important in the field of refractive surgery, especially in the selection and evaluation of intraocular lenses, such as monofocal iol, bifocal iol, or trifocal iol, following cataract surgery. Furthermore, it is known that lens design, such as spherical aberration correction or the specific diopter of a lens, can impact the shape of the defocus curve. However, visual acuity defocus curve is not always sensitive to optical changes, thus as the constrast sensitivity function is an optional measure to visual acuity for detecting changes in optical quality at far distance, this approach can be extended using contrast sensitivity defocus curves along all the visual range with the Multifocal Lens Analyzer.

With the continuous advancements in the field of ophthalmology and refractive surgery, there are always new findings related to defocus curves. For instance, recent studies might demonstrate the superiority of a particular type of intraocular lens in terms of visual acuity or minimal visual disturbances. The advent of newer lenses, such as an extended depth of focus intraocular lens, could lead to changes in the defocus curve, indicating improved vision at different distances. Furthermore, developments in testing protocols or technologies, like the Abbott Medical Optics or Johnson Vision, Alcon, Medicontur, Zeiss, etc., can lead to more varieties of defocus curves shapes and extension.

The range of defocus measured often depends on the specific patient and their visual needs. However, the general range can be between +1.00 diopters (D) to -4.00 diopters, including measurements at a far distance, intermediate distance, and near. The aim is to create a comprehensive view of the patient's vision beyond corrected distance visual acuity, understanding how their visual acuity changes over this range of defocus.

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1. Purpose of our Apps

1.1 Please be aware that all our apps have been designed for research and not for medical purposes. They are not intended for use in the diagnosis of disease or other conditions, or in the cure, mitigation, treatment, or prevention of disease. The information provided by our Apps is not intended to use for the benefit of individual patients, but it is intended to evaluate the results along a sample of patients in order to conduct research. By downloading and using our apps you agree to use them only for research purposes.

2. About the Data Stored in your Device

2.1 For achieving the previous purpose, the app stores in the device non-personal data using a pseudo-identifier in order to ensure that only the user who introduces the data might identify the subject. The developer does not collect any personal data from you or from the pseudo-anonymized data that you introduce in the app. All the data remain only in your device and can be encryptep by Apple and stored in the iCloud if you conduct an iCloud backup.

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5. Changes to this Terms and Conditions

5.1 The developer may update our Terms and Conditions from time to time. Thus, you are advised to review this page periodically for any changes. I will notify you of any changes by posting the new Terms and Conditions on this page. These changes are effective immediately after they are posted on this page.

6. Contact

If you have any questions or suggestions about my Terms and Conditions, do not hesitate to contact us.