Disruptive Innovation and Refractive IOLs: How the Game Will Change With Adjustable IOLs

Light adjustable intraocular lenses in cataract surgery: considerations

PURPOSE OF REVIEW

Light adjustable intraocular lens (LAL) is a promising concept in cataract surgery. This review explores considerations for the use of LALs.

RECENT FINDINGS

Through updates, the safety of LALs and light delivery devices have been enhanced, enabling more efficient treatment with lower ultraviolet (UV) energy. Preoperative topography and aberration are essential for understanding indications for LALs. Furthermore, when determining intraocular lens power, it is crucial to factor in potential postoperative myopia or hyperopic adjustments. This is achieved by establishing a proper postimplantation refractive target and considering potential wavefront changes. Postoperative adjustments for defocus and astigmatism have demonstrated excellent outcomes. Monovision strategy by adjustable blended vision of LALs revealed distance vision of 20/20 along with near vision of J2 in 96% of patients. However, the results of clinical studies on postrefractive cataract surgery showed contrasting outcomes at distance, indicating the need for further research results regarding its effectiveness. A new postoperative workflow needs to be designed to enable a systematic follow-up process.

SUMMARY

LALs are safe and demonstrate promising refractive outcomes. To achieve appropriate results, understanding the changes in optical characteristics associated with adjustment and constructing a new postoperative workflow are necessary.

Immediately sequential bilateral cataract surgery

PURPOSE OF REVIEW

This review aims to clarify the advantages and disadvantages of immediately sequential bilateral cataract surgery (ISBCS) based on recent studies, illustrate the safety of this approach, the cost-effectiveness, and present the importance of inclusion protocols for the best results.

RECENT FINDINGS

In recent studies, the authors found no evidence of an increased risk of bilateral devastating complications such as endophthalmitis with ISBCS based on descriptive evidence compared to delayed sequential bilateral cataract surgery (DSBCS). Furthermore, recent studies on cost analyses showed that ISBCS resulted in fewer costs and significant cost savings to third-party payers, patients, and society compared to DSBCS.

SUMMARY

The ISBCS surgical approach decreases hospital visits, reduces costs, and provides rapid visual rehabilitation and neuro adaptation. The risk of bilateral simultaneous complications is now recognized to be very rare with intracameral antibiotics and compliance with correct protocols. With new generations of optical biometry and lens calculation formulas, refractive surprises are occasional for normal eyes. However, refractive surprise is controversial, especially in the implantation of presbyopia correction intra-ocular lenses, which must be evaluated carefully in the ISBCS approach.

New Nitinol-based Thermomechanically Adjustable IOL Technology

PURPOSE

To evaluate the feasibility of new adjustable intraocular lens (IOL) technology.

METHODS

The foldable adjustable IOL consists of a nitinol mechanism placed in a haptic-optic cradle. Heating actuators on the nitinol mechanism with a continuous green laser achieve controlled movement of the mechanism and optic. Activation occurs in controlled steps: rotation in 1-degree steps over 360 degrees, and anterior posterior movement in 0.25-diopter (D) steps with a range of +1.50 D. The IOL was tested in vitro and in vivo in a rabbit eye. Foldability and unfolding were demonstrated through a 2.6-mm cartridge.

RESULTS

The adjustable lens mechanism was successfully tested in vitro and in vivo. Activation resulted in a change in optic position relative to the haptics and the capsular bag. Activation of the lever and ratchet mechanism showed radial advancement of the IOL clockwise and counterclockwise. In vivo rotatory movement was achieved after activation by the argon laser at 1 week after implantation. Anterior to posterior movement was accomplished by activating the circular spring actuator mechanism in the laboratory model. Uneventful folding and unfolding were performed.

CONCLUSIONS

A new adjustable IOL with a mechanism that responds in measured steps had been shown to move as planned after activation by argon laser. This was successful in the laboratory in both radial and anterior posterior movement. The radial movement was also proven in vivo in an animal model. Further refinement of the prototype is currently being undertaken. [J Refract Surg. 2023;39(10):662-667.].

Current State of the Art and Next Generation of Materials for a Customized IntraOcular Lens according to a Patient-Specific Eye Power

Intraocular lenses (IOLs) are commonly implanted after surgical removal of a cataractous lens. A variety of IOL materials are currently available, including collamer, hydrophobic acrylic, hydrophilic acrylic, PHEMA copolymer, polymethylmethacrylate (PMMA), and silicone. High-quality polymers with distinct physical and optical properties for IOL manufacturing and in line with the highest quality standards on the market have evolved to encompass medical needs. Each of them and their packaging show unique advantages and disadvantages. Here, we highlight the evolution of polymeric materials and mainly the current state of the art of the unique properties of some polymeric systems used for IOL design, identifying current limitations for future improvements. We investigate the characteristics of the next generation of IOL materials, which must satisfy biocompatibility requirements and have tuneable refractive index to create patient-specific eye power, preventing formation of posterior capsular opacification.

Light adjustable intraocular lenses: an updated platform for cataract surgery

PURPOSE OF REVIEW

Light adjustable intraocular lenses (LALs) are a relatively new platform for cataract surgery that is shifting the paradigm for intraocular lens placement following cataract removal.

RECENT FINDINGS

LALs may have additional utility in patients with prior refractive surgery and complex ocular conditions, as they give the surgeon greater latitude in preoperative intraocular power calculations to meet postoperative refractive goals.

SUMMARY

Further study of best candidates for LALs is warranted. Current best candidates are patients who can comply with treatment and have decreased accuracy in calculating the preoperative intraocular power requirement.

Immediately sequential bilateral cataract surgery importance during the COVID-19 pandemic

Cataract surgery is one of the most frequently performed types of surgery in the world. Most patients suffer from bilateral cataract and while cataract surgery of only one eye is effective in restoring functional vision, second eye surgery leads to further improvements in health-related quality of life, and is cost effective. At present, most patients undergo cataract surgery in both eyes on separate days, referred to as delayed sequential bilateral cataract surgery (DSBCS). An alternative procedure involves operating both eyes on the same day, but as separate procedures, known as immediately sequential bilateral cataract surgery (ISBCS). The aim of this study is to evaluate the effectiveness and costs of ISBCS compared to DSBCS. ISBCS is an important topic in ophthalmology, especially during the recent COVID-19 pandemic as it is necessary to decrease the hospital visits in order to prevent the contagious risk of this disease. There are well-documented advantages in terms of reduced costs for patients and health-care systems as well as more rapid visual rehabilitation and neuroadaptation. Based on recent studies, the risk of bilateral simultaneous complications is now recognized to be rare with the advent of intracameral antibiotics and strict protocols in this surgical approach. With the use of more sophisticated optical biometry and the newest generation lens calculation, refractive surprises are rare for normal eyes. A widely recognized protocol from the International Society of Bilateral Cataract Surgeons needs to adhere in order to prevent any further complications and obtaining better outcomes.

Immediate bilateral sequential cataract surgery

PURPOSE

There is a constant controversy between performing cataract surgery for one eye or for both eyes in the same surgical session. The objective of this study is to review the scientific evidence on the efficacy and safety, determine the reduction of costs of sequential bilateral cataract surgery on the same day compared to unilateral cataract surgery, as well as to compare the rate of associated complications.

METHODS

A comprehensive search of the PubMed and Web of Science databases has been conducted to identify relevant articles on sequential bilateral cataract surgery from 2000 to 31 of December of 2020.

RESULTS

Literature shows that there is strong evidence demonstrating the efficacy and safety of same-day sequential bilateral cataract surgery. Studies have not found a higher rate of postoperative complications compared to unilateral cataract surgery.

CONCLUSIONS

Same-day sequential bilateral cataract surgery is a good surgical option for the resolution of the cataract, provides rapid visual rehabilitation and without greater risks than unilateral surgery. It also provides a reduction in sanitary costs. There is a psychological fear of performing bilateral surgery due to the potential risk of complications that would affect both operated eyes. In this article we discuss the efficacy, safety, complications rate and associated costs in sequential bilateral cataract surgery in the same surgical act.

Recent Advances of Intraocular Lens Materials and Surface Modification in Cataract Surgery

Advances in cataract surgery have increased the demand for intraocular lens (IOL) materials. At present, the progress of IOL materials mainly contains further improving biocompatibility, providing better visual quality and adjustable ability, reducing surgical incision, as well as dealing with complications such as posterior capsular opacification (PCO) and ophthalmitis. The purpose of this review is to describe the research progress of relevant IOL materials classified according to different clinical purposes. The innovation of IOL materials is often based on the common IOL materials on the market, such as silicon and acrylate. Special properties and functions are obtained by adding extra polymers or surface modification. Most of these studies have not yet been commercialized, which requires a large number of clinical trials. But they provide valuable thoughts for the optimization of the IOL function.

Use of presbyopia-correcting intraocular lenses in patients with prior corneal refractive surgery

PURPOSE OF REVIEW

Corneal refractive surgery has achieved spectacle-free vision for millions of patients, but this aging population is now developing cataracts. Many of these patients may wish to avoid reliance on glasses after cataract surgery. Presbyopia-correcting intraocular lenses (IOLs) offer a solution, but corneal changes after refractive surgery may compound higher order aberrations and dysphotopic symptoms associated with these IOLs. This review aims to discuss potential factors that could aid in determining suitable postkeratorefractive candidates for presbyopia-correcting IOLs.

RECENT FINDINGS

Studies investigating which preoperative measures influence outcomes are lacking. The few studies that have examined presbyopia-correcting IOLs in postkeratorefractive patients report that satisfactory outcomes are possible. However, recommendations for preoperative thresholds appear limited to expert opinion and studies involving virgin corneas.

SUMMARY

As the number of presbyopia-correcting IOLs and postkeratorefractive patients grows, continued investigation into relevant preoperative factors and appropriate IOLs is required to make evidence-based decisions. The current literature shows that with rigorous counseling and appropriate patient selection, presbyopia-correcting IOLs can provide postkeratorefractive patients with satisfactory results and spectacle independence. In addition, the development of postoperative modifiable IOLs may prove to be the preferred option.

Future Intraocular Lens Technologies

The future of intraocular lens (IOL) technology has already begun with a number of recent innovations. The postoperative change of refractive power will lead to a customized fine-tuning that provides patients with the individual vision they expect and with as much spectacle independence as possible. The latest-generation (2.0) Light-Adjustable Lens (RxSight) was recently introduced into clinical practice, with the first results being very encouraging. Other methods of altering the power of an already implanted IOL are under development. The same can be said about the correction of presbyopia, the so-called last frontier in refractive surgery. Extended depth-of-focus IOLs have been introduced, as has the technology of the pinhole IOL. The latter has therapeutic potential beyond the refractive aspect and has already proven helpful in cases of iris defects and irregular corneas. Several technologies are currently being tested to achieve-finally-an accommodative IOL. One such concept uses the (remaining) strength of the ciliary muscle, whereas another is triggered by the pupil reaction when shifting focus from far to near. Not an IOL itself, but rather a high-tech innovation that so far has mostly been implanted during cataract surgery, is a microelectronic sensor that measures habitual intraocular pressure (IOP) at any given time and promises to revolutionize the management of glaucoma patients. The last generation of this device (Eyemate; Implandata Opthalmics Products GmbH) is implanted during small-incision cataract surgery; the latest development is an even smaller sensor that will be inserted suprachoroidally before, in the near future, such a device will be part of a capsular ring. These IOP sensors are a prime example that IOL technology will continue to be a driving force in ophthalmology, with a positive impact far beyond cataract surgery.

Handling regular and irregular astigmatism during cataract surgery

PURPOSE OF REVIEW

There are several different approaches to handling regular and irregular astigmatism during cataract surgery, but still much debate on which solutions are most effective given unique patient circumstances. In this review, we examine recent literature and studies to highlight some of the most effective ways to plan preoperatively, manage regular and irregular astigmatism during cataract surgery, as well as managing postoperative complications.

RECENT FINDINGS

Recent developments in technology have provided increased courses of action for astigmatism management during cataract surgery. Additional options of toric IOLs with presbyopic platforms, light adjustable lenses, intraocular pinhole lenses, online technological tools and platforms, wavefront or topographic laser technology, and phototherapeutic keratectomy are all effective solutions to managing regular and irregular astigmatism. In this review, we will explore optimal approaches for unique situations.

SUMMARY

With increased technology, research, and methods, correcting regular and irregular astigmatism during cataract surgery is achievable in most patients. With in-depth preoperative planning, analysis of patient-specific factors, and a tailored approach, surgeons can obtain excellent uncorrected vision for patients.