In vitro power profiles of multifocal simultaneous vision contact lenses

Repeatability of in vitro power profile measurements for multifocal contact lenses

“…The power profiles of the Air Optix Aqua Multifocal (Alcon Laboratories, USA) with low, medium and high addition, and the Focus Progressives were measured in a previous study [2]. The refractive power provided by those lenses was found to be dependent on the patient's pupil size, and contact lens design For example, due to Air Optix Low addition and Focus progressives power profiles, 3 mm pupil diameter is needed to reach distance correction with the former one, whereas 1.8 mm pupil diameter is needed to do distance correction with the later one.…”

“…This optical device uses a measuring light source with radiance peaking at 546 nm and obtains light deviations, from which it is possible to calculate the power characteristics of optical lenses. Detailed descriptions of the method used to measure power profiles can be found elsewhere [2,9,11]. The NIMO is able to obtain spherical and cylinder power with its axis, Zernike coefficients, and contact lens power profiles.…”

“…Objective measurements of the power profiles provide helpful information for prescribing lenses on presbyopic patients [1], give practitioners a better understanding of the behaviour of these contact lenses, and enhance fitting nomograms. For example, it has been reported [2] that modifying the distance nominal power in a multifocal contact lens has double effect: change both the near addition, and the pupil diameter for which the lens provides the distance correction. There are different techniques that have been used to measure contact lens power profiles objectively: Meier et al [3] used a series of double aperture stops on a lensometer to measure the power distribution across the Bausch & Lomb bifocal lenses; Bullimore et al [4] assessed power variation across the surface of a multifocal lens using a video-keratographic method; and Collins et al [5] measured power variations across the optic zone using a computer-interfaced vectometer.…”

Optical power distribution of refractive and aspheric multifocal contact lenses: Effect of pupil size

“…As we reported in a preliminary study [27], and related to the aspheric power profile of other multifocal designs (center-near), it should be considered that the modification of the distance nominal power could affect the refractive power of the lens through a direct relation to the pupil size. If a clinician chooses a more positive lens the addition power would be increased, however, the negative refractive power of the lens would be placed in the extreme periphery of the optical zone.…”

“…Source: From Montés-Micó et al [27]. rear surface spherical (back optic zone radius of 8.6 mm) centernear design, with a total lens diameter of 14.0 mm.…”