What is an aspheric lens implant?

you have cataracts that obscure your vision, it’s likely you’ll be recommended for cataract surgery. This process removes the natural lens of one’s eye and replaces it with an artificial lens, named an intraocular lens .

They also have a higher ability for hazard detection compared to the IOL that has UV only. Therefore, it is worth affirming that blue light filtering really helps to raise the functional vision of patients to a great extent, which makes it a perfect choice for most. An excellent lens will always make surgery smooth and effective and the results will be high visual quality. Vision quality has been expressed by the idea spread function and the modulation transfer function . The PSF describes the light distribution on the retina of a point source and it could be expressed with the Strehl ratio.

Aspheric Lenses: Better Vision & Better Appearance

To judge the postoperative visual quality of cataract patients with extreme myopia after implantation of aspheric intraocular lenses . Eighteen eyes with an axial length longer than 28 mm were contained in the extreme myopia group, and the other 15 eyes were contained in the nonextreme myopia group. Half a year after cataract surgery, best-corrected visual acuity , contrast sensitivity, and wavefront aberrations were measured, and subjective visual quality was assessed. The BCVA improved significantly after surgery for both groups, and patients in the nonextreme myopia group achieved better postoperative BCVA due to better retinal status of the eyes. The evaluation of contrast sensitivity without glare was exactly the same in both groups, whereas patients in the nonextreme myopia group performed better at intermediate spatial frequencies under glare conditions. The two groups didn’t show a big change in high-order aberrations. With regard to subjective visual quality, the composite scores of both groups did not differ significantly.
The study was approved by the Ethics Committee of Eye & ENT Hospital, Fudan University. Studies have shown that monofocal IOLs produce similar ramifications of distance vision as multifocal IOL implantation postoperatively. The optical quality of a lens system can be tested within an optics or physics laboratory using bench apertures, optic tubes, lenses, and a source. Refractive and reflective optical properties could be tabulated as a function of wavelength, to approximate system performances; tolerances and errors may also be evaluated. As well as focal integrity, aspheric lens systems can be tested for aberrations before being deployed. Convex aspheric curvatures are employed in lots of presbyopic vari-focal lenses to improve the optical power over section of the lens, aiding in near-pointed tasks such as reading.

• Measurements of ocular wavefront error were performed 3 months after cataract surgery utilizing the OPD Scan-II aberrometer/topographer NIDEK Co Ltd, Gamagori, Japan.
• This kind of lens can be made from any material, including polycarbonate and Trivex.
• The second kind of aspherical surfaces, called “zonal asphere,” is
• The next logical step is really a compensation procedure in line with the true individual SA, rather than on average values.

Your eye’s natural lens plays a significant role in focusing images on the retina. Eyeglasses or contacts usually can correct slight refractive errors caused by early cataracts, but they cannot sharpen your vision if a sophisticated cataract is present. Some authors defined that a range of decentration inside a SA-correcting IOL would perform better or equal when compared to a standard spherical IOL. This range was reported to be between 0.0 and 0.3–0.8 mm, with regards to the design of the lens and simulation conditions . In a previous publication, we summarized the data on the IOL decentration from various sources and found that the clinically observed decentration is between 0 and 1 mm but most frequently about 0.3 mm . Others showed that there is a tendency for IOLs decentering and tilting into nasal direction with mirror symmetry between both eyes .

Asphericity Quality

“The other issue is that we don’t fully understand how aberrations interact,” he continues. The number of lens powers available to dispensing opticians for filling prescriptions, even yet in an aspheric form, is bound practically by how big is the image formed on the retina. Computer-generated holograms represent a method for the interferometric determination of the deviation of the lens from the nominal geometry. These generate an aspherical wavefront in the prospective shape and therefore enable the determination of deviations of the lens from the prospective shape in an interference image. CGHs should be manufactured designed for each test item and are therefore only economical for series production. The non-spherical curvature of an aspheric lens can be created by blending from the spherical into an aspherical curvature by grinding the curvatures off-axis. Dual rotating axis grinding can be utilized for high index glass that’s not easily spin molded, as the CR-39 resin lens is.

“Spherical aberration will not correlate with the ‘super normal’ high-contrast visual acuity described in the Air Force pilot study,” he says. In terms of the surgery itself altering spherical aberration, Dr. Packer believes that any effect is probably insignificant. Implanting an aspheric IOL avoids increasing this aberration—and an IOL with negative spherical aberration may even return the optical system to zero spherical aberration by offsetting the cornea’s slight positive aberration. Another way for producing aspheric lenses is by depositing optical resin onto a spherical lens to create a composite lens of aspherical shape. Small glass or plastic aspheric lenses could be made by molding, that allows cheap mass production. Due to their low priced and good performance, molded aspheres are commonly used in inexpensive consumer cameras, camera phones, and CD players.
The lens provides patients with excellent near and distance vision, all of which is distinct. Most patients also report good intermediate or arms’ length vision aswell. AcrySof® IQ PanOptix IOL by Alcon is an innovative implant that reduces the necessity for glasses after cataract surgery.

About Dr Hillson

Larger optic diameter can also facilitate postoperative peripheral retinal examination and treatment, because eyes with high myopia are in risky of lattice degenerations, retinal holes and tears, and retinal detachment . Due to the larger optic diameter,