Acri.LISA (Carl Zeiss Meditec AG, Jena, Germany)
LISA is an acronym for (L) light intensity distribution 65% far and 35% near with an addition of 3.75 D for near sight; (I) independent from pupil size; (S) smooth refractive/diffractive surface profile (SMP Technology, which means the phase zones of the optic extend over the entire lens surface; and (A) optimized aspheric optic.
The smooth steps of Acri.LISA's optical principle help reduce disturbing light phenomena. The bifocal lens offers reduced glare and improved contrast sensitivity as well as good near, intermediate, and distance vision.
With an A-constant of 117.6, this monobloc hydrophilic lens has a hydrophobic surface treatment. The Acri.LISA is injected through a 1.5- to 2.2-mm incision, and due to the SMP-Technology, light phenomena (ie, reflection, halos) will be significantly reduced.
Akreos AO Microincision, Akreos AO, and SofPort AO (Bausch & Lomb, Rochester, New York)
Bausch & Lomb's three aspheric, aberration-free lenses, the Akreos AO Microincision lens (Akreos MI60), the Akreos AO, and the SofPort AO, are all designed with two prolate aspheric surfaces, so they are free from spherical aberrations and immune to the adverse effects of decentration. The optical performance is unaffected by decentration and pupil size owing to the lenses uniform center-to-edge power. The aberration-free design of these aspheric lenses leaves the eye with its natural degree of corneal positive spherical aberrations, providing patients with a good depth of field.
The Akreos MI60 lens has the additional advantage of being implantable through a 1.8-mm incision using a wound-assisted technique, and it forms part of the Bausch & Lomb MICS platform. The four-point fixation design provides excellent stability, with the novel haptic design conforming to capsular bag contraction in three dimensions without transferring contraction forces to the optic.
Both the Akreos MI60 and Akreos AO lenses are made from the clinically proven Akreos acrylic material and are available from 0.00 D to 9.00 D, in 1.00 D increments, and 10.00 D to 30.00 D in 0.50 D increments. The SofPort AO is a three-piece silicone lens. These three lenses are available with adapted single-use injection systems.
Aqua-Sense PAL, Aqua-Sense III PAL, and Aqua 4V PAL (Ophthalmic Innovations International, Ontario, California)
These three precision aspheric lenses (PAL) consist of a square-edge design and are made from acrylic hydrophilic material—leading to fewer internal reflections. The main feature that sets the optics apart from other aspheric designs is that these lenses take into account a broad range of aberrations arising with lens misalignment, according to the company. For example, a typical aspheric lens will often perform worse than a spherical lens if it becomes tilted or decentered. Modulation transfer function measurements show that performance of the PAL lenses is comparable to or better than that of spherical optics (in cases of significant lens decentration and tilt).
Additionally, these lenses offer improved image quality and contrast sensitivity, especially in low-light conditions, according to a company brochure.
The Aqua-Sense PAL and Aqua-Sense III have an overall diameter of 13 mm and a suggested A-constant of 118.2. All three lenses are available from 0.50 D to 30.00 D in 0.50 D increments.
Aspira-aAY, Aspira-aXA, and Secura-sAY (HumanOptics AG, Erlangen, Germany)
The Aspira-aAY foldable monobloc posterior chamber lens from HumanOptics consists of a hydrophilic microcryl with an UV inhibitor and yellow-coloring agent for blue-light protection. The optic is aberration free, and offers a 360º lens epithelial cell barrier.
Suggested A-constant for the lens is 118.4, and it is available in 0.50 D increments from 10.00 D to 30.00 D, and 1.00 D increments from 0.00 D to 9.00 D.
The Aspira-aXA lens is a foldable monobloc posterior chamber IOL with an aspheric posterior surface. It is made of hydrophilic acrylic with a UV inhibitor. The estimated A-constant is 118.3. It is recommended for patients with additional high myopia or hyperopia to achieve improved functional vision and reduced glare sensitivity.
The Aspira-aXA was developed to give patients the best image quality, as expressed by the point spread function (PSF). There is higher focal light point density with aspherics, better image quality, and a PSF closer to one. According to HumanOptics literature, spherical IOLs do not even reach PSF values of 0.1.
The lens has a sharp-edge design and can be implanted through a small incision (sub–2.5-mm) with the Medicel Viscoject Injector (Medicel AG, Wolfhalden, Switzerland) and 2.2 cartridge set. The lens is easy to fold, safe to implant, and there is less glare in the case of larger pupils. The lens has up to 7-mm diameter, which is suitable for surgeons in case of potential interventions in the ocular fundus.
The Secura-sAY is recommended for standard cataract cases as well as extreme hyperopia or myopia. Depending on IOL power, different aspheric surfaces enable reduced glare sensitivity and improved functional vision. The foldable three-piece posterior chamber lens has a hydrophobic optic with a UV inhibitor and blue-light protection. The lens is aberration-correcting with an aspheric posterior surface, and 360º sharp-optic edge.
This lens is available from 7.00 D to 31.00 D, in 0.50 D increments and 32.00 D to 36.00 D and -6.00 D to 6.00 D in 1.00 D increments. Other diopters can be delivered according to individual specifications.
C-flex Aspheric and Superflex Aspheric (Rayner Intraocular Lenses, East Sussex, UK)
The Rayner C-flex Aspheric and Superflex Aspheric IOLs include the Amon-Apple Enhanced Square Edge for low posterior capsule opacification (PCO) rates, antivaulting technology for optimal centration, and a single-use soft-tipped injector capable of insertion through a sub–3-mm incision.
The C-flex Aspheric has an optic body diameter of 5.75 mm and an overall length of 12 mm. The estimated A-constant is 118, and the dioptric range spans from 18.00 D to 29.50 D in 0.50 D increments and 30.00 D to 34.00 D in 1.00 D increments.
The Superflex Aspheric has an optic body diameter of 6.25 mm and an overall length of 12.5 mm. The estimated A-constant is 118, and the dioptric range spans from -10.00 D to 22.00 D in 0.50 D increments.
Preloaded AF-1 (FY-60AD; Hoya, Frankfurt, Germany)
The AF-1 is available as a standalone IOL or in a preloaded system isert. The lens consists of a hydrophobic acrylic material with a blue-light filter and PMMA haptics. To provide for high image quality under realistic conditions, Hoya's aspheric IOL progressively combines the advantages of both spherical and aspherical optic curvatures (ABC-design), according to company literature.
In conventional fully compensating aspheric IOLs, the image quality and contrast sensitivity decrease significantly with increasing decentration and tilt of the IOL. Recent reports show that the average decentration value is between 0.24 and 0.53 mm under realistic conditions.
The aspheric balanced curve design of Hoya's aspheric IOLs minimizes this negative effect of decentration and tilt. The Hoya ABC-design provides the advantage of better contrast sensitivity by an aspheric surface design. With a suggested A-constant of 118.4, this lens is available from 6.00 D to 30.00 D in 0.50 D increments.
Preloaded Aspheric IOL Injector KS-3Ai (STAAR Surgical, Monrovia, California)
The KS-3Ai is the only apsheric IOL that comes preloaded in its own injection system, which guarentees a sterile pathway into the eye. The IOL is implanted through a sub–3-mm incision and currently may be as small as 2.75 mm. According to the company, the KS-3Ai IOL demonstrates stability due to its polymide haptics and provides contrast sensitivity like the eye of a 20-year-old. Dislocation, vaulting, optic axis tilt, and rotation were analyzed and confirmed the lens' ability to avoid malpositioning. Additionally, during a 12-month study published in the Journal of the Eye, the preloaded KS-3Ai achieved the lowest PCO rates of the three lenses studied.
The aspheric optic design includes a double-square edge, an optic diameter of 6 mm, and an over length of 12.5 mm. The lens also features a 10º-haptic angle and a suggested A-constant of 119.5. It is available from 12.50 D to 28.50 D in 0.50 D increments.
Quatrix Aspheric Preloaded (Croma-Pharma GmbH, Korneuburg, Austria)
The Quatrix Aspheric Preloaded IOL features four haptics for excellent centration, according to the company. Thus, the one-piece hydrophilic acrylic lens includes eight supports for a large contrast zone to prevent capsular folds. Its aspheric optic guarantees superior contrast sensitivity.
The Quatrix preloaded injector system guarantees easy and safe folding and prevents the lens from damage. Designed to fit all capsular bag diameters, the Quatrix IOL also includes a 360º square-edge to avoid cell migration and a notch to ensure the correct side is implanted facing up.
This 11-mm lens has a suggested A-constant of 119.6, and requires a 2.8-mm incision. It is available from 10.00 D to 30.00 D in 0.5 D increments.
AcrySof Restor Aspheric and AcrySof IQ (Alcon Laboratories, Inc., Fort Worth, Texas)
The AcrySof Restor Aspheric IOL is the next generation in IOL technology and can be injected through a 2.2-mm incision. It has 12 diffractive step heights, covering the central 3.6-mm anterior lens surface. Restor is available in 6.00 D to 30.00 D, and the A-constant is 118.9 for ultrasound biometry. Some surgeons find the need for a slightly higher A-constant when using the IOLMaster (Carl Zeiss Meditec AG). The lens adds 4.00 D at the lens plane and 3.20 D at the spectacle plane. Using apodization, this lens has been shown to allocate appropriate light energy to light levels and minimize photic phenomena. As the pupil constricts, the Restor equilibrates light energy for either near or distant vision. When the pupil dilates, the lens catches less incident light to defocus the near image.
In addition to the three-piece lens, Restor is also available as a single-piece IOL with a blue-light filter.
The AcrySof IQ has a low rate PCO. Additionally, the slow and controlled unfolding of this lens during its implantation makes it ideal for eyes with small compromises in the capsular bag (eg, a limited central defect).
The AcrySof IQ lens is more than 9% thinner than the regular AcrySof single-piece and Natural platforms (Alcon Laboratories, Inc.), which makes it possible to implant it through 2.2-mm incisions with the Monarch D (Alcon Laboratories, Inc.) cartridge.
The aspheric optic of the AcrySof IQ lens provides -0.20 µm of spherical aberration. With larger pupils, this correction enhances image quality by counteracting the remaining positive spherical aberration of the cornea.
The AcrySof IQ has an A-constant of 118.7 and a modified L-haptic. The lens is available in a range of 6.00 D to 30.00 D in 0.50 D increments.
Softec HD (Lenstec Inc., St. Petersburg, Florida)
This high-definition microincision aspheric IOL with precision diopters comes in 0.25 D increments from 18.00 D to 25.00 D; 0.50 D increments ranging from 10.50 D to 29.50 D; and whole diopters increments from 5.00 D to 36.00 D. With a 5.75-mm optic, the equal conic biaspheric optic is 12 mm in length. The modified C-haptic has a 0º angulation and an A-constant of 118.
Tecnis (Advanced Medical Optics, Inc., Santa Ana, California)
The Tecnis aspheric IOL has -0.27 µm of spherical aberration to compensate for the spherical aberration on the cornea, thereby providing a better image contrast and improving vision in low light situations, such as night driving.
Available in a range of 5.00 D to 34.00 D, the diffractive pattern of the Tecnis is placed on the posterior surface of the lens, and the prolate anterior face suppresses Z4 spherical aberration. The Tecnis adds 4.00 D at the lens plane and 2.80 D at the spectacle plane, with an A-constant of 119.1. This silicone IOL has high stability, as the polyvinylidene haptics are C-shaped. It is implanted through a 2.8-mm incision.
XL Stabi ZO and Invent ZO (Carl Zeiss Meditec SAS, La Rochelle, France)
Zeiss Optic (ZO) aspheric lenses combines the advantages of both negative spherical aberration lenses and aberration-neutral lenses. ZO lenses provide excellent image quality and contrast sensitivity for the largest range of patients while demonstrating very low sensitivity to decentration and tilt, according to the company. Both ZO lenses are preloaded in their cartridge to allow for easy and reproducible injection with SkyJet disposable injector and offer different geometries for a larger flexibility of implantation. To optimize the contact surface with the equator of the capsular bag, as well as secure postoperative stability, the XL Stabi ZO (Figure 1) and Invent ZO (Figure 2) feature a three- and four-haptics design, respectively. The flexible haptics are optimized to fit bag retraction and secure long-term centration.
The Invent ZO features a posterior aspheric optic for the correction of most corneal spherical aberrations. Manufactured with hydrophilic acrylic (28%), this lens has a 0º-haptic angulation and an A-constant of 118.1. Implanted into the capsular bag, the lens power ranges from 14.00 D to 30.00 D. The IOL has square edges and filters UV light.
The XL Stabi ZO includes the same aforementioned components of the Invent ZO, however, the haptic angulation is 10º
Both IOLs feature markers to identify the correct side of implantation for proper positioning during surgery.
This aspheric IOL guide ran previously as the wrong version in the October 2007 issue of CRST Europe. We have reprinted the correct version as a service to our readers. The Editors apologize for the mistake.
