Premium and Specialized Intraocular Lenses

The development of foldable lenses, and perhaps more importantly, the small-incision capsular surgical techniques that accompany them, have been instrumental in achieving a vast reduction in cataract surgery complications. The excellent optical and visual rehabilitory benefits of small incision phacoemulsificationfoldable intraocular lens (IOL) surgery, including reduced astigmatism, quick recovery, and many other advantages, are well known. This modern procedure has achieved a state of vision restoration as well as vision rehabilitation. Modern cataract surgery is now a genuine form of refractive surgery.

The history of cataract surgery with IOLs is one of the extensive trial and errors, with many dead ends. By far, the most important and basic element required for success with IOLs is fixation. Indeed, the generations of IOLs are named according to the type of fixation used during each era.

The six generations that we identify signify the continuous movement forward, as surgeons attempted to improve IOL fixation. The move from Ridley's initial lens (Generation I) to the early anterior chamber lenses and iris-fixated lenses (Generations II and III) were basically attempts to overcome decentration issues (recall that Ridley’s IOL had no haptics). In addition, the move toward a second generation of anterior chamber lenses (Generation IV), usually implanted after intracapsular cataract extraction (ICCE), was in part caused by a desire to avoid the posterior capsule opacification (PCO) or secondary cataract that often occurred after early methods of extracapsular cataract extraction (ECCE). The last generation includes “specialized” IOLs, which are the focus of this book.

During the aging process, the spherical aberration (SA) induced by the natural lens shifts from negative to positive values, impairing optical quality. Standard spherical intraocular lenses (IOLs) similarly induce positive SA. To deal with this problem aspheric IOLs have been designed to induce a negative or neutral SA, effectively reducing optical SA in a manner similar to the lens in a young phakic eye. It has been postulated that implanting an aspheric IOL would improve image clarity over that provided by a standard spherical IOL because of reduced optical aberrations. Multiple simulations, as well as clinical trials evaluating mesopic and photopic contrast sensitivity, have shown that aspheric IOLs indeed provide improved spectacle corrected contrast function over comparable spherical IOLs. This is especially true for under scotopic conditions where maximal pupillary dilation increases the magnitude of optical SA errors. However, the clinical significance of these contrast improvements for the average cataract patient has been called into question for many reasons, primarily because senile miosis effectively minimizes the magnitude of post-operative optical SA. Recent efforts to use aspheric IOLs to individualize post-operative ocular SA have shown promising visual results; however the ideal post-operative spherical aberration has not yet been determined. Further study into optimizing the interaction between the full spectrum of higher order aberrations in the pseudophakic eye may be useful in defining the future role for aspheric IOL technology in enhancing visual function in pseudophakia.

Intraocular lenses (IOL) that filter some blue light were introduced in the 1990s and were suggested to reduce the risk of Age related macular degeneration and uveal melanoma. The potential benefits and harm from blocking blue light has been debated. In this chapter we will discuss the evidence for the protective effects and the negatives of these IOLs.

After the development of non-astigmatic cataract surgery, a new generation of intraocular lenses, able to manage previously existing corneal astigmatism, has experienced a great expansion. Different choices for the surgeon include the possibility of correcting simultaneously presbyopia, special designs for sulcus implantations and customized dioptric powers. The keys to success when implanting these IOLs are correct power calculation and correct surgical management with pre-surgical marking of the cylindrical axis and ensuring correct alignment at the end of the procedure.

Cataract surgery has undergone dramatic improvements, rehabilitation is quick, the complication rate is decreasing, IOL material and calculations have improved, and excellent uncorrected distance visual acuity can be expected in most cases where the eye is healthy. Currently, one of the major challenges of cataract surgery is presbyopia correction. Patients expect excellent distance vision, as well as spectacle freedom for near vision. Multifocal IOLs, better termed bifocal IOLs, and recently trifocal IOLs, create 2 or 3 foci. These IOLs have improved in recent years and can provide a good solution for those who seek to reduce spectacle dependency. However, the downside to these IOLs includes halo, glare and reduced distance vision contrast sensitivity. In this chapter, we will review the basic principles of multifocal IOLs and their clinical results. It is worthy to note that currently only the Alcon AcrySof ReSTOR (Fort Worth, TX, USA) MIOL and the Tecnis ZMB00 (Abbott Laboratories, Inc., Abbott Park, IL, USA) MIOL have FDA approval and a large database of detailed clinical results.

The purpose of this chapter is to provide perspective on intraocular lens technology designed to achieve accommodative function in the pseudophakic state. We briefly introduce the fundamental physiologic optics of accommodation and presbyopia, and then review the achievements and limitations of multifocal intraocular lens technology. We detail the historical development and current status of three single optic accommodative designs, the crystalens, the 1CU and the Tetraflex. Summaries of published and presented clinical studies demonstrate the range of accommodative amplitude expected with each lens, while imaging and biometric data provide conflicting evidence regarding the mechanism of action of these devices. We then examine the Synchrony dual optic accommodative IOL in detail, providing summaries of all available clinical data along with supportive imaging results. In a final section we discuss a couple of novel technologies that lie on the horizon of accommodative IOL implementation, the NuLens and the FluidVision lens.

This chapter addresses the current status of phakic intraocular lens (PIOL) surgery to correct refractive errors. Depending on the position, three types of PIOLs are recognized: angle-supported anterior chamber, iris-fixated anterior chamber, and posterior chamber PIOLs, which are usually fixated in the ciliary sulcus. The main models of each type of PIOLs are introduced, also patient selection criteria, surgical techniques and applications of anterior segment imaging techniques. Results of the different models of PIOL are summarized, including specific PIOL or surgery related complications. Implantation of PIOL is an effective, safe, predictable, and stable procedure to correct moderate and high refractive errors. Complications are rare and mostly related to the position and the type of the implant.

In this chapter we will describe the rational for supplementary IOL that were developed mainly for the correction of post-surgery refractive error. We will describe the alternative and the advantages of the supplementary IOLs. Supplementary IOLs are also available for astigmatism correction and as a multifocal version with or without a blue light protection. We will describe and discusses the clinical results of the available IOL.

The trend toward minimally invasive surgery has been introduced in many fields of medicine, including ophthalmology. Cataract surgery has evolved over the last few decades from very large incision intracapsular cataract extraction to mini- and recently microincision cataract surgery (MICS) with an incision size of less than 2 mm. Recent innovations in phacoemulsification and intraocular lens technology have enabled this concept. Although cataract surgery can be performed through an incision less than 1 mm long, most IOLs require an incision of more than 2.0 mm in length.

Most MICS-IOLs are constructed of one-piece hydrophilic acrylic material. They used to have insufficiently sharp posterior optic edges and broad haptic-optic junctions that compromised the optic-edge barrier effect. Improvements in those designs have achieved better hydrophilic acrylic IOLs in terms of vision quality and prevention of posterior capsular opacity. Recently, a hydrophobic three-piece IOL, which features a slim haptic junction and a sharp optic edge, became available. This chapter reviews the characteristics of recently introduced microincision IOLs.

Further investigation is needed to improve the IOL design to match the microincision platform, without compromising vision quality.

The light adjustable lens (LAL) provides the unique capability of a novel intraocular lens material that can be adjusted noninvasively with ultraviolet (UV) light following cataract surgery. Residual refractive errors after modern cataract surgery may cause problems for many patients, requiring the use of spectacles or even further surgery to correct this problem. The LAL is composed of a specially-designed polymer structure with embedded macromers and light-sensitive molecules. Upon UV irradiation, the shape and refractive power of the lens can be changed. The lens has passed rigorous in vitro and in vivo animal studies for biocompatibility and ability to accurately be adjusted. Presently, clinical trials are underway in the United States; the lens is commercially available in Europe. Results have shown the lens to predictably correct up to 2 diopters (D) of myopic or hyperopic error and 1.75 D of astigmatism, holding the adjustment with up to 9 months of follow-up. Higher-order and multifocal patterns have successfully been applied to the LAL, although neither have been studied in clinical trials as of yet. Researchers continue to study the optics and visual outcomes for patients as well as look to more advanced technologies, such as adaptive optics, to combine with the LAL. This lens has shown great potential and will doubtlessly play a large role in the future of intraocular lenses.

Iris defects such as congenital aniridia, ocular albinism, iris coloboma, uveitis, trauma, or surgical misadventure face a unique challenge for the ophthalmologist. Relatively conservative solutions like colored contact lenses, corneal tattooing has limited results. In this chapter we will review the intraocular devices that are currently marketed to the world ophthalmic community. A few cases will be discussed for demonstrational purposes.

Full size intraocular lens (IOL) has a great potential for restoring full range of vision and not just a fixed monofocal, bifocal or trifocal distance without the inherited of the multifocal IOLs. In this chapter we will describe the attempts to develop full size lens and there current status.

Magnifying devices for patients with macular diseases have existed for about 70 years. The development of various devices over the years is related to the evolving understanding of the physiology and optical parameters of the eye, the devices and the relationship between the devices and the eye.

In the last decade, we have witnessed a tremendous development in the field of intraocular telescopic devices. These telescopes use the optical and physiologic advantages of their intraocular location, and resolve many of the disadvantages of external or combined telescopic devices.

Although most studies are ongoing, the Implantable Miniature Telescope (IMT) is the first and currently the only FDA approved device. The IMT is also the only device known to have been studied in a large, controlled, clinical trial. Other devices, such as the Lipshitz Macular Implant (LMI) and the IOL-Vip have been studied in small series of patients only. All devices resulted in improved visual acuity in implanted patients, but a correlation to improved quality of life was not apparent. Unfortunately, there are no uniform, comparable, clinical parameters among these studies.

Intraocular telescope implantation is challenging from the aspects of surgical technique and visual rehabilitation. A low complication rate (such as endothelial cell loss) and a programmed rehabilitation process are crucial for obtaining best results from an implanted telescope.

In this chapter we describe the optical and physiological aspects of low vision aids. We present the historical background and the technological progress, including recent clinical trials, emphasizing the current evaluations of intraocular magnifying devices.