Harold Ridley and the invention of the intraocular lens

Thermo-sensitive Poloxamer based antibacterial anti-inflammatory and photothermal conductive multifunctional hydrogel as injectable, in situ curable and adjustable intraocular lens

Cataract patients look forwards to fewer postoperative complications and higher vision quality after surgery. However, the current intraocular lens (IOL) implanted after cataract surgery neither can adjust focal length in response to ciliary muscle contraction as natural lens nor have the ability to prevent postoperative complications. Herein, a thermosensitve Poloxamer based hybrid hydrogel with antibacterial anti-inflammatory and photothermal functional elements doping was designed and used as injectable, in situ curable, and adjustable IOL (FHTAB IOL). The FHTAB IOL was composed of thermosensitve triblock-polymer F127DA and a small amount of HAMA, combined with BP NS, TA, and Ag NPs. FHTAB IOL can be injected into the empty lens capsule after cataract surgery via an injectable thermos-gel under NIR illumination and then be rapidly cured to form a full-size IOL under short-time blue light irradiation. The designed injectable FHTAB IOL possesses high transparency and transmittance, with a refractive index similar to the natural lens and adjustable properties. It was stabilized as a refractive medium without any leakage in the eye. In addition, the TA and Ag NPs loaded in the FHTAB IOL displayed significant antibacterial and anti-inflammatory effects in vitro and vivo. This study presents a potentially effective new strategy for the development of multifunctional adjustable IOLs.

[Overview of intraocular lenses with optics for correcting presbyopia]

BACKGROUND

In recent years intraocular lenses (IOLs) for correcting presbyopia have been significantly improved and diversified. There are currently many different IOL models based on a wide variety of optical designs.

OBJECTIVE

The wide variety of available IOL solutions to correct presbyopia can be challenging for surgeons and patients. In everyday practice, the question is which IOL is best for which patient.

MATERIAL AND METHODS

This overview describes and categorizes the currently available implants. The respective optical properties are analyzed and clinical study results are discussed, in particular those evaluating visual performance and the occurrence of photic phenomena.

RESULTS

Monofocal-plus IOLs provide improved intermediate visual acuity with optimal distant visual acuity and minimal photic phenomena. Extended depth of field (EDoF) IOLs extend the depth of field through different optical principles and provide good distant and intermediate visual acuity. Trifocal lenses enable the greatest independence from spectacles at the price of a higher probability of dysphotopsia.

CONCLUSION

The selection of the most suitable IOL for correction of presbyopia requires a balance between the patient's visual needs and possible side effects. An adequate knowledge of the currently available implants allows a patient-oriented selection of IOLs.

Through the Cat-Map Gateway: A Brief History of Cataract Genetics

Clouding of the transparent eye lens, or cataract(s), is a leading cause of visual impairment that requires surgical replacement with a synthetic intraocular lens to effectively restore clear vision. Most frequently, cataract is acquired with aging as a multifactorial or complex trait. Cataract may also be inherited as a classic Mendelian trait-often with an early or pediatric onset-with or without other ocular and/or systemic features. Since the early 1990s, over 85 genes and loci have been genetically associated with inherited and/or age-related forms of cataract. While many of these underlying genes-including those for lens crystallins, connexins, and transcription factors-recapitulate signature features of lens development and differentiation, an increasing cohort of unpredicted genes, including those involved in cell-signaling, membrane remodeling, and autophagy, has emerged-providing new insights regarding lens homeostasis and aging. This review provides a brief history of gene discovery for inherited and age-related forms of cataract compiled in the Cat-Map database and highlights potential gene-based therapeutic approaches to delay, reverse, or even prevent cataract formation that may help to reduce the increasing demand for cataract surgery.

Elastomeric Polyesters in Cardiovascular Tissue Engineering and Organs-on-a-Chip

Cardiovascular tissue constructs provide unique design requirements due to their functional responses to substrate mechanical properties and cyclic stretching behavior of cardiac tissue that requires the use of durable elastic materials. Given the diversity of polyester synthesis approaches, an opportunity exists to develop a new class of biocompatible, elastic, and immunomodulatory cardiovascular polymers. Furthermore, elastomeric polyester materials have the capability to provide tailored biomechanical synergy with native tissue and hence reduce inflammatory response in vivo and better support tissue maturation in vitro. In this review, we highlight underlying chemistry and design strategies of polyester elastomers optimized for cardiac tissue scaffolds. The major advantages of these materials such as their tunable elasticity, desirable biodegradation, and potential for incorporation of bioactive compounds are further expanded. Unique fabrication methods using polyester materials such as micromolding, 3D stamping, electrospinning, laser ablation, and 3D printing are discussed. Moreover, applications of these biomaterials in cardiovascular organ-on-a-chip devices and patches are analyzed. Finally, we outline unaddressed challenges in the field that need further study to enable the impactful translation of soft polyesters to clinical applications.

Safety, biocompatibility, and potential functionality of a new accommodative intraocular lens: An experimental study in rabbits

This study aims to evaluate the safety, biocompatibility, and functionality of a new accommodative intraocular lens (IOL) (LUZ, patent PCT/ES2016/070,813) after implantation in rabbit eyes. LUZ (Study) and EyeCee® plus a capsular ring (Control) were implanted in rabbits (n = 8 each) after phacoemulsification. Intraoperative follow-up, long-term clinical follow-up, and functional IOL studies were carried out periodically for up to 180 days. A macroscopic examination of the eyeballs to reveal abnormalities and determine the implant centering and a microscopic examination to semi-quantify cell and tissue response were performed. Statistical analysis of the collected data was finally achieved. During follow-up, no significant changes in the general condition nor the clinical evaluation were observed between both groups. However, Study IOL remained centered throughout the study and did not present severe complications as observed in the Control group. Functional studies did not reveal significant differences between both materials. Study showed better centering, fewer adhesions, and maintenance of an opening capsular bag compared to the Control. Local biological effects caused by Study implantation are minimal and comparable to the Control. Therefore, LUZ showed no clinical signs or histological response of adverse reaction to the implanted material, according to UNE-EN ISO 11979-5 and 10993-6. Functionality must be confirmed in another animal species with greater lens accommodation capacity than the rabbit. LUZ keeps the capsular bag open, favoring its centering and avoiding fibrosis and adherence to the bag; this allows potential accommodation of this IOL and theoretically enables the patient to focus dynamically.

Implanting toric implantable collamer lens displays better astigmatism correction than implantable collamer lens combined with manually limbal relaxing incision

BACKGROUND

This retrospective study aimed to compare the outcomes of toric implantable collamer lens (TICL) surgery with those of implantable collamer lens (ICL) implantation combined with limbal relaxing incision (LRI) in patients with low myopia and astigmatism.

METHODS

A total of 40 eyes of 28 patients who underwent TICL implantation and 40 eyes of 27 patients who underwent ICL implantation combined with manually LRI between 2021 and 2022 were included. Primary outcomes were manifest sphere and cylinder, intraocular pressure, visual acuity, and astigmatism parameters at 1 day, 1 week, and 1, 3, and 6 months postoperatively.

RESULTS

The two surgeries showed comparable effects on manifest sphere and cylinder, intraocular pressure, and visual acuity (all p > 0.1). Surgery-induced astigmatism (SIA) was maintained as stable in the TICL group (1.73 to 1.68, p = 0.420), but was significantly reduced in the ICL/LRI group (1.74 to 1.17, p = 0.001) from preoperative to postoperative 6 months. The TICL group displayed significantly higher SIA and correction index at postoperative 1, 3, and 6 months than the ICL/LRI group (at 6 months: SIA, 1.68 (1.26, 1.96) vs., 1.17 (1.00, 1.64), p = 0.010; CI: 0.98 (0.78, 1.25) vs. 0.80 (0.61, 1.04), p = 0.018). No complications occurred during follow-up.

CONCLUSIONS

The effects of ICL/LRI are comparable to those of TICL in correcting myopia. TICL implantation displays better astigmatism correction than ICL/LRI.

Cemented Femoral Stem Fixation: Back to the Future

BACKGROUND

Periprosthetic fractures following elective and non-elective hip arthroplasty remain one of the most common modes of early failure.

METHODS

This symposium will explore the current role of cemented fixation and periprosthetic fracture, focusing on history and rationale for cemented stem fixation, registry data and other potential advantages of cemented stem fixation. A meticulous and methodical surgical technique of cemented stem fixation is paramount to the success and will be thoroughly discussed.

RESULTS

The role of stem fixation, and its effect on periprosthetic fracture is well-documented in the literature. Yet despite this, the utilization of cemented stem fixation remains low in the United States. This paradox is multifactorial.

CONCLUSIONS

In addition to a notable reduction in the risk of periprosthetic femur fractures, cemented stem fixation has numerous other advantages and is reproducible with a methodical surgical technique.

Development Pattern of Medical Device Technology and Regulatory Evolution of Cataract Treatment

To prevent regulation from becoming an obstacle to healthcare technological innovation, regulation should evolve as new healthcare technologies are developed. Although regulation is closely related to healthcare technology development, there are few studies that view healthcare technological advances from the multi-layered perspective of papers, patents, and clinical research and link this with regulatory evolution. Therefore, this study tried to develop a new method from a multi-layer perspective and draw regulatory implications based on it. This study applied this method to intraocular lens (IOLs) for cataract treatment and detected four major healthcare technologies and two recent healthcare technologies. Moreover, it discussed how current regulations evaluate these technologies. The findings provide implications for healthcare technological advances and the evolutionary direction of regulation through the example of IOLs for cataract treatment. This study contributes to the development of theoretical methods for co-evolution with regulations based on healthcare technology innovation.

Advanced Retina Implants

PURPOSE

To discuss the role of advanced retinal implants in retinitis pigmentosa and age-related macular degeneration.

DESIGN

Presented by Mark S. Humayun as the Charles Schepen's Lecture on the Retina Subspecialty Day of the American Academy of Ophthalmology in 2021.

PARTICIPANTS

The details of subjects, participants, and controls are provided in the references pertaining to each study.

METHODS

Review of published literature and clinical trials.

MAIN OUTCOME MEASURES

Visual and anatomic outcomes from retinal implants.

RESULTS

Retinal implants have been researched over the past few decades, and some have been advanced into the clinic. Two types of implants-bioelectronic and stem cell-based-have shown promising results in restoring some level of vision in patients with inherited retinal degeneration and geographic atrophy. These implants differ in their constructions, locations of implantation, and safety profiles. The results from some of these retinal implants have shown signs of efficacy, and 1 retinal implant, the Argus II, has been approved by the United States Food and Drug Administration.

CONCLUSIONS

Careful consideration of the design of the implant and associated surgical techniques are necessary to obtain a stable and effective long-term interface between the implant and the retina.

Spectral transmittance of animal intraocular lenses in comparison with the spectral properties of their biological lenses

PURPOSE

To determine the spectral transmittance of artificial intraocular lenses (IOLs) designed for various species (dog, cat, chinchilla, eagle, tiger) and compare them to the spectral properties of the biological lenses of these species.

METHODS

Twenty-seven IOLs were scanned with a spectrophotometer fitted with an integrating sphere.

RESULTS

All IOLs transmitted long wavelengths well before cutting off sharply at short wavelengths, with insignificant transmission below ca. 340 nm. In comparison with the IOLs, the biological lenses of the cat, dog, and probably the chinchilla transmitted significantly more short wavelengths. The spectral properties of the biological lenses of eagles and tigers, while uncertain, may be a closer match to the IOLs made for these species.

CONCLUSION

It is not known if there are any visual or behavioral consequences for animals caused by a mismatch between the spectral properties of their biological lenses and IOLs. However, following IOL implantation there might be a change in the perceived hue of objects due to the removal of UV wavelengths which form a normal part of the visible spectrum for these species and/or a decrease in sensitivity.

The effects of premium intraocular lenses on presbyopia treatments

Background

Presbyopia has become a global disease affecting the world's aging population. Among various treatments, cataract extraction and intraocular lens (IOL) implantation have become the most popular and common methods of presbyopia correction. During the twentieth century, IOLs have underwent significant innovation and advancements to meet the patients' high demands for functional vision at all distances.

Main Text

To meet the increasing needs for excellent near and intermediate vision for daily activities, some premium IOLs with more than one focus have been developed, for example, the refractive MfIOLs, diffractive MfIOLs, extended depth of field (EDOF) IOLs, and accommodating IOLs (AIOLs) were introduced to meet this need. In addition, the add-on MfIOLs have been explored as promising supplementary IOLs for pseudophakic presbyopia. When selecting the MfIOLs, the IOLs' features, patients' characteristics, preoperative eye conditions, and treatment expectations should be considered.

Conclusions

In this review, we focus on the multifocal IOLs (MfIOLs) commonly used for presbyopia correction and systematically summarized their optical designs and clinical outcomes. More evidence-based studies are required to provide guidelines for MfIOL selection, provide maximum visual benefits, and develop personalized visual solutions in the future.

The economics of medical procedure innovation

This paper explores the economic incentives for medical procedure innovation. Using a proprietary dataset on billing code applications for emerging medical procedures, we highlight two mechanisms that could hinder innovation. First, the administrative hurdle of securing permanent, reimbursable billing codes substantially delays innovation diffusion. We find that Medicare utilization of innovative procedures increases nearly nine-fold after the billing codes are promoted to permanent (reimbursable) from provisional (non-reimbursable). However, only 29 percent of the provisional codes are promoted within the five-year probation period. Second, medical procedures lack intellectual property rights, especially those without patented devices. When appropriability is limited, specialty medical societies lead the applications for billing codes. We indicate that the ad hoc process for securing billing codes for procedure innovations creates uncertainty about both the development process and the allocation and enforceability of property rights. This stands in stark contrast to the more deliberate regulatory oversight for pharmaceutical innovations.

Interaction of micropatterned topographical and biochemical cues to direct neurite growth from spiral ganglion neurons

Functional outcomes with neural prosthetic devices, such as cochlear implants, are limited in part due to physical separation between the stimulating elements and the neurons they stimulate. One strategy to close this gap aims to precisely guide neurite regeneration to position the neurites in closer proximity to electrode arrays. Here, we explore the ability of micropatterned biochemical and topographic guidance cues, singly and in combination, to direct the growth of spiral ganglion neuron (SGN) neurites, the neurons targeted by cochlear implants. Photopolymerization of methacrylate monomers was used to form unidirectional topographical features of ridges and grooves in addition to multidirectional patterns with 90^o angle turns. Microcontact printing was also used to create similar uni- and multi-directional patterns of peptides on polymer surfaces. Biochemical cues included peptides that facilitate (laminin, LN) or repel (EphA4-Fc) neurite growth. On flat surfaces, SGN neurites preferentially grew on LN-coated stripes and avoided EphA4-Fc-coated stripes. LN or EphA4-Fc was selectively adsorbed onto the ridges or grooves to test the neurite response to a combination of topographical and biochemical cues. Coating the ridges with EphA4-Fc and grooves with LN lead to enhanced SGN alignment to topographical patterns. Conversely, EphA4-Fc coating on the grooves or LN coating on the ridges tended to disrupt alignment to topographical patterns. SGN neurites respond to combinations of topographical and biochemical cues and surface patterning that leverages both cues enhance guided neurite growth.

Intraocular lenses as drug delivery devices

Cataract surgery is one of the most common and safe surgical procedures nowadays. However, it is not free of risks as endophthalmitis, ocular inflammation and posterior capsule opacification (PCO) can appear as post-surgery complications. The usual eye drop therapy used as prophylaxis for the former two complications has limited bioavailability. In turn, the prevention of PCO involves an adequate surgical technique and a careful choice of intraocular lens (IOL) design and material. Also, different drugs have been tested to reduce incidence of PCO, but no prophylaxis demonstrated to be completely effective. In the past few years, IOLs have been proposed as drug delivery devices to replace or/assist the usual eye drop therapy in the post-operatory period. The great advantage of drug loaded IOLs would be to ensure a continuous drug delivery, independent of patient's compliance without requiring any further action besides IOL implantation. The biggest challenge of drug loaded IOLs production is to achieve a controlled and extended release that meet therapeutic needs without inducing toxicity to the surrounding ocular tissues or affecting the physical properties of the lens. This review starts by addressing the possible complications after cataract surgery, as well as the most commonly adopted prophylaxis for each of them. The various types of IOLs are described and their main advantages/disadvantages are discussed. The different strategies pursued to incorporate drugs into the IOLs and control their release, which include soaking the IOL in the drugs solution, supercritical impregnation, surface modifications, and attachment of drug reservoirs to the IOL, among others, are reported. For each strategy, a summary of the publications is presented, which includes the target complication, the types and amounts of released drugs and the IOL materials. A brief description of each individual study is given afterwards. Optimization of drug loaded IOLs through mathematical modelling and possible issues raised by their sterilization are also tackled. At the end, the future commercialization of drug loaded IOLs is commented.

Polymeric Materials for Eye Surface and Intraocular Applications

Ocular applications of polymeric materials have been widely investigated for medical diagnostics, treatment, and vision improvement. The human eye is a vital organ that connects us to the outside world so when the eye is injured, infected, or impaired, it needs immediate medical treatment to maintain clear vision and quality of life. Moreover, several essential parts of the eye lose their functions upon aging, causing diminished vision. Modern polymer science and polymeric materials offer various alternatives, such as corneal and scleral implants, artificial ocular lenses, and vitreous substitutes, to replace the damaged parts of the eye. In addition to the use of polymers for medical treatment, polymeric contact lenses can provide not only vision correction, but they can also be used as wearable electronics. In this Review, we highlight the evolution of polymeric materials for specific ocular applications such as intraocular lenses and current state-of-the-art polymeric systems with unique properties for contact lens, corneal, scleral, and vitreous body applications. We organize this Review paper by following the path of light as it travels through the eye. Starting from the outside of the eye (contact lenses), we move onto the eye's surface (cornea and sclera) and conclude with intraocular applications (intraocular lens and vitreous body) of mostly synthetic polymers and several biopolymers. Initially, we briefly describe the anatomy and physiology of the eye as a reminder of the eye parts and their functions. The rest of the Review provides an overview of recent advancements in next-generation contact lenses and contact lens sensors, corneal and scleral implants, solid and injectable intraocular lenses, and artificial vitreous body. Current limitations for future improvements are also briefly discussed.

What New Lens Technologies Are on the Horizon?

Collapse

A Critical Appraisal of New Developments in Intraocular Lens Modifications and Drug Delivery Systems for the Prevention of Cataract Surgery Complications

Cataract surgery is the commonest ophthalmic surgery worldwide. The replacement of the diseased lens with a synthetic one (intraocular lens-IOL) remains the treatment of choice, despite its potential complications that include infection, inflammation and posterior capsule opacification. The potential for drug delivery via the IOL has been researched extensively over a period of twenty-five years, yet there is very limited progress in transferring the findings from research to everyday practice. The objective of this review is to assess the progress made in the field of IOL lens modifications and drug delivery systems over the past five years. Thirty-six studies that were conducted during the past five years were identified and deemed suitable for inclusion. They were grouped in three broad categories, studies that described new methods for loading a drug onto the IOL, assessment of the effects of drugs that were loaded to the IOL and studies that assessed the effects of non-pharmaceutical modifications of IOLs. While considerable progress is continually being made with regard to methods and materials, there is still little capitalization upon these research studies, with no commercially available IOL-based drug delivery system being available. Close cooperation between researchers in basic sciences (chemistry, physics, materials science and pharmacy), clinical researchers, IOL manufacturers and the pharmaceutical industry is an important prerequisite for further development.

Peripheral image quality in pseudophakic eyes

The purpose of this work was to evaluate peripheral image quality in the pseudophakic eye using computational, physical, and psychophysical methods. We designed and constructed a physical model of the pseudophakic human eye with realistic dimensions using a corneal phantom and a board-only camera that was pivoted around an axis that matched the anatomical center of a human retina, assuming a radius of curvature of 12 mm, while it was submersed in a 23.4 mm long water filled chamber to emulate human ocular axial length. We used this optical setup to perform direct recording of the point spread function (PSF) and the associated retinal images for a commercial intraocular lens (IOL). Additionally, psychophysical tests were carried out to investigate the impact of the off-axis astigmatism in peripheral visual performance, where spectacle-induced astigmatism simulated the pseudophakic conditions in healthy subjects. Our findings using the physical eye model confirm the existence of large amounts of astigmatism in the periphery of the pseudophakic eye. The psychophysical tests revealed a significant reduction of detection sensitivity in the peripheral visual field. The latter suggests that off-axis astigmatism in patients implanted with IOLs may have performance and safety implications for activities requiring efficient peripheral vision.

Semmelweis Reflex: An Age-Old Prejudice

BACKGROUND

Semmelweis reflex is a human behavioral tendency to stick to preexisting beliefs and to reject fresh ideas that contradict them (despite adequate evidence). We aim to familiarize the readers with the term that not only has a significant historical background but also grave clinical implications.

METHODS

A keyword search for "Semmelweis reflex," "Belief perseverance," "handwashing," and "Idea rejection" was conducted using PubMed Central, MEDLINE, and Google SCHOLAR. Literature published in paper-based journals and books was also searched. All manuscripts pertaining to these keywords were thoroughly analyzed for this review.

RESULTS

The first section of our paper briefs the story of Ignaz Semmelweis and brushes on the contributions of other intellectual researchers that were rebuffed initially. The discussion further explains the root cause of this dismissal, an inherent bias against uncertainty that may be at the core of our fear for new ideas. Finally, this review explores the means by which we can prevent ourselves from being a victim of rejection.

CONCLUSIONS

The age-old prejudice that is Semmelweis reflex is explored in this review. With careful and thorough study design, scientific rigor, and critical self-analysis of the manuscript, one can avoid being victimized by this reflex. The dual edged nature of this reflex lays unveiled when its importance is highlighted in the prematurely accepted medical failures. Understanding that any new idea goes through the grill of being critically analyzed and perceived encourages the scientist to hold on to the original thought as it may rather be practice changing.

[Future through history]

The motto of the German Ophthalmolological Society (DOG) Congress 2019 "Ophthalmology: our medical discipline with a future" raises the question of what "ophthalmological future" should really be, what are its driving forces and what are the foundations of its design. The design of the future, usually equated with "progress", naturally always takes place out of the present, which itself is a product of the past. History, like time and evolution, is always a continuum. Although we may not always be very clear about this, the history always influences the future. "Future through history" especially arises where lessons are learnt from "historical mistakes", where good but forgotten ideas are rediscovered and where history is used for a better understanding.

Noncontact method for sensing thickness and refractive index of intraocular lens implants using a self-calibrating dual-confocal laser caliper

We present a fiber-optic dual-confocal laser caliper method for noncontact high-precision sensing and measuring thickness and refractive index of intraocular lens (IOL) implants. The principle of the method is based on sensing and measuring the confocal intensity response of the laser beam reflection from the opposite object surfaces, which provides the advanced feature of having no limitations on the object shape, thickness, and transparency. Using single-mode optical fibers and a 658-nm laser source, the thickness measurement accuracy was assessed to be as high as 5  μm. In addition, refractive index of a transparent object with thickness smaller than the working distance of the focusing lenses can be measured. The thickness and refractive index of a planoconvex IOL were measured with a high accuracy.

Glistenings, anterior/posterior capsular opacification and incidence of Nd:YAG laser treatments with two aspheric hydrophobic acrylic intraocular lenses - a long-term intra-individual study

PURPOSE

To compare two hydrophobic acrylic intraocular lenses (IOLs) regarding long-term anterior/posterior capsular opacification (ACO/PCO) development and need for neodymium:Yttrium-Aluminum-Garnet (Nd:YAG) laser treatment due to visually disturbing PCO, and to study development of glistenings in the IOL materials.

METHODS

In a prospective, randomized, intra-individual, comparative trial, 50 cataract patients received either an AcrySof IQ^® SN60WF (Alcon, Fort Worth, TX, USA) or a Tecnis^® ZCB00 (Abbott Medical Optics, Santa Ana, CA, USA) IOL in the first operated eye, and the second eye received the IOL type not implanted in the first eye. Anterior/posterior capsular opacification (ACO/PCO) and fibrosis were monitored with slit-lamp photography and semi-automated digital analysis 2 and 3 years postoperatively. Glistenings were semi-quantitatively assessed in slit-lamp photographs. Nd:YAG laser treatment for visually disturbing PCO was monitored.

RESULTS

Visual outcomes were similar for the two IOLs. Anterior capsular fibrosis and/or opacification developed more often in SN60WF eyes. Mean PCO area percentage was larger in ZCB00 eyes 3 years after surgery, but severity score did not differ with statistical significance between the two IOLs. Six ZCB00 eyes and 2 SN60WF eyes underwent Nd:YAG laser treatment during a mean of 4 years 8 months after surgery. This difference was not statistically significant. A high amount of glistenings developed in most SN60WF IOLs, while only few ZCB00 IOLs displayed a low degree of glistenings.

CONCLUSION

Visual outcomes, PCO development over time and need for Nd:YAG laser treatment were similar for the two IOLs. Anterior capsule fibrosis/contraction and glistenings were more pronounced with the SN60WF IOL.

Comparison of Hill-radial basis function, Barrett Universal and current third generation formulas for the calculation of intraocular lens power during cataract surgery

IMPORTANCE

This study represents a novel comparison of recently introduced intraocular lens power calculation formulas.

BACKGROUND

To compare current new generation formulas for calculating the intraocular lens power for a standard cohort of patients undergoing cataract and lens replacement surgery in a private group practice in Australia.

DESIGN

Retrospective case series comparison.

PARTICIPANTS

Postoperative results from 400 consecutive patients undergoing implantation of an SN60WF intraocular lens post cataract removal by 12 surgeons were used.

METHODS

Refractive outcomes were compared with expected targets to determine the predicted refractive outcomes using the Hill-radial basis function, Barrett Universal II and readily available third or fourth generation intraocular lens power calculation formulas.

MAIN OUTCOME MEASURE

Mean absolute predicted error.

RESULTS

The mean absolute predicted difference ranged from 0.30 to 0.34 D. There was no overall significant difference in the predicted difference or variance between formulas. All formulas achieved greater than 78.3% of eyes within ±0.5 D of intended refraction. The Hill-radial basis function and Barrett formulas provided the lowest mean numerical error compared with existing formulas in short and long eyes, respectively. The Barrett Universal II formula had the lowest percentage of refractive surprises (>1 D from predicted error) across all axial lengths.

CONCLUSIONS AND RELEVANCE

Acceptable outcomes can be achieved with optical biometry, consistent surgical technique and use of current intraocular lens power calculation formulas. The Barrett Universal II formula may provide the lowest risk of refractive surprise compared with other intraocular lens power calculation formulas.

Getting Undone Technology Done: Global Techno-assemblage and the Value Chain of Invention

The global techno-assemblage shapes the continued lagging of southern countries and firms behind those from the global north. The biotechnology industry is one form of this assemblage and operates according to inter-related logics (i.e., economic, hybrid and social) which are shaped by particular governmental policies and corporate decisions to minimise risk and philanthropic efforts. Within this form, a non-profit ophthalmic consumables manufacturing company, Aurolab, in southern India creates new innovations. According to the ‘technology follower’ conceptual framework by innovation studies and management scholars, biotechnology firms have two options to ‘move up’ the international value chain of invention: they must either ‘catch up’ at a very high rate, or ‘leap-frog’ up through research, design and development. Aurolab innovates to heal eye diseases. They focus on affordability issues through research and development as well as design and development. At Aurolab, they shift between these two strategies depending upon the drug or device they are working on. This article considers additional incentives to refocus firms on local needs-based technology according to a social logic. As Aurolab demonstrates, a new focus on technology to address structural inequality may be necessary to get ‘undone technology’ done.

Sir Harold Ridley (1906-2001): televising and filming ophthalmic surgery and eye examinations

Sir Harold Ridley is well known for his pioneering intraocular lens implantation surgery. He also had a significant commitment to the televising and filming of surgery. In his 1950 Television in Ophthalmology paper, Ridley describes the techniques he used to capture his surgery in monochrome and later in full colour for audiences at St Thomas' Hospital.

Confocal laser method for quantitative evaluation of critical optical properties of toric intraocular lenses

PURPOSE

To present a proof-of-concept study on the development and implementation of an innovative confocal laser method platform for precise quantitative evaluation of critical optical properties unique to toric intraocular lenses (IOLs).

SETTING

U.S. Food and Drug Administration, Optical Therapeutics and Medical Nanophotonics Laboratory, Silver Spring, Maryland, USA.

DESIGN

Experimental study.

METHODS

The optical properties of hydrophobic toric IOLs were evaluated with a confocal laser method that was modified to isolate the 2 planes of focus that are observed with toric IOLs.

RESULTS

The results show the confocal laser method has the potential to measure the orthogonally separated optical powers and then calculate them to the commonly referenced spherical equivalent and cylinder powers of toric IOLs with high accuracy (≤1 μm of focal length measurement). Furthermore, the proposed confocal laser method design includes a new component for precise differentiation of the 2 focal planes and isolation of the 2 focal points, and thus for accurate measurement of the anterior cylinder axis of toric IOLs.

CONCLUSION

The modifications to the confocal laser method platform enabled the quantitative evaluation of optical properties attributed to toric IOLs.

FINANCIAL DISCLOSURE

None of the authors has a financial or proprietary interest in any material or method mentioned.

Assessment of Optical Quality at Different Contrast Levels in Pseudophakic Eyes

Purpose. To assess visual function using Optical Quality Analysis System (OQAS) at varying levels of contrast in pseudophakic eyes. Methods. The study included patients admitted to Seoul St. Mary's Hospital between January and February 2012: 143 pseudophakic eyes with one of five intraocular lens types, examined 2–6 months after cataract surgery, and 93 normal eyes (enhanced visual acuity (VA) < 0.1 logMAR) in age-matched controls. Subjects were examined at three contrast levels using the OQAS. Results. At 100%, 20%, and 9% contrast, simulated mean VA was 0.16 ± 0.18 logMAR, 0.30 ± 0.18 logMAR, and 0.52 ± 0.17 logMAR, in normal eyes, and 0.16 ± 0.12 logMAR, 0.33 ± 0.20 logMAR, and 0.56 ± 0.21 logMAR, respectively, in pseudophakic eyes. Simulated VA decreased significantly when contrast was reduced, regardless of ocular status, age group, and lens type (p < 0.05). There were no significant differences between normal and pseudophakic eyes among subjects aged 50–69 (p > 0.05). Among subjects aged 70–79, pseudophakic eyes showed improved simulated VA (p = 0.000) and objective scattering index values (p = 0.008). Conclusions. Patients with intraocular lenses have similar or superior visual function when compared to those with normal eyes at 2–6 months after cataract surgery, even under low-contrast conditions.

Polydopamine-Gelatin as Universal Cell-Interactive Coating for Methacrylate-Based Medical Device Packaging Materials: When Surface Chemistry Overrules Substrate Bulk Properties

Despite its widespread application in the fields of ophthalmology, orthopedics, and dentistry and the stringent need for polymer packagings that induce in vivo tissue integration, the full potential of poly(methyl methacrylate) (PMMA) and its derivatives as medical device packaging material has not been explored yet. We therefore elaborated on the development of a universal coating for methacrylate-based materials that ideally should reveal cell-interactivity irrespective of the polymer substrate bulk properties. Within this perspective, the present work reports on the UV-induced synthesis of PMMA and its more flexible poly(ethylene glycol) (PEG)-based derivative (PMMAPEG) and its subsequent surface decoration using polydopamine (PDA) as well as PDA combined with gelatin B (Gel B). Successful application of both layers was confirmed by multiple surface characterization techniques. The cell interactivity of the materials was studied by performing live-dead assays and immunostainings of the cytoskeletal components of fibroblasts. It can be concluded that only the combination of PDA and Gel B yields materials possessing similar cell interactivities, irrespective of the physicochemical properties of the underlying substrate. The proposed coating outperforms both the PDA functionalized and the pristine polymer surfaces. A universal cell-interactive coating for methacrylate-based medical device packaging materials has thus been realized.

A novel full-angle scanning light scattering profiler to quantitatively evaluate forward and backward light scattering from intraocular lenses

Glare, glistenings, optical defects, dysphotopsia, and poor image quality are a few of the known deficiencies of intraocular lenses (IOLs). All of these optical phenomena are related to light scatter. However, the specific direction that light scatters makes a critical difference between debilitating glare and a slightly noticeable decrease in image quality. Consequently, quantifying the magnitude and direction of scattered light is essential to appropriately evaluate the safety and efficacy of IOLs. In this study, we introduce a full-angle scanning light scattering profiler (SLSP) as a novel approach capable of quantitatively evaluating the light scattering from IOLs with a nearly 360° view. The SLSP method can simulate in situ conditions by controlling the parameters of the light source including angle of incidence. This testing strategy will provide a more effective nonclinical approach for the evaluation of IOL light scatter.

Developments in the correction of presbyopia II: surgical approaches

PURPOSE

To discuss the various static and dynamic surgical approaches which attempt to give presbyopes good vision at far, intermediate and near viewing distances.

CONTENT

Static methods broadly adopt the same optical techniques as those used in presbyopic contact lens correction and aim to satisfy the needs of the presbyope by increasing binocular depth-of-focus, often using monovision as well as simultaneous-imagery. Dynamic methods generally attempt to make use of at least some of the still-active elements of the accommodation system. They include procedures which are supposed to modify the relative geometry of the ciliary muscle and lens, or which reduce the stiffness of the presbyopic lens either by replacing it with other natural or man-made material or by subjecting it to femtosecond laser treatment. Alternatively the natural lens may be replaced by some form of intraocular lens which changes power as a result of forces derived from the still-active ciliary muscle, zonule and capsule, or other sources.

CONCLUSIONS

At present, multifocal intraocular lenses appear to offer the most consistent and reliable surgical approach to surgical presbyopic correction. They have obvious advantages in convenience and stability over optically-similar, simultaneous-image presbyopic contact lenses but this must be balanced against their relative inflexibility in cases of patient dissatisfaction. Dynamic methods remain largely experimental. Although some approaches show promise, as yet no method has demonstrated a reliable, long-term ability to correct distance refractive error and to appropriately change ocular power in response to changes in viewing distance over the normal range of interest.

Impact of environmental temperature on optical power properties of intraocular lenses

Optical power properties of lenses and materials in general can be influenced by thermal changes of the material and surrounding medium. In the case of an intraocular lens (IOL) implant, the spherical power (SP), cylinder power, (CP), astigmatism, and spherical aberration are the critical fundamental properties that can significantly impact its efficacy. Directly evaluating how changes in temperature can affect these optical properties may show the importance of considering temperature when evaluating IOL optical characteristics. In this paper, we present a quantitative study on evaluating the impact of environmental temperature changes on IOL fundamental optical properties by testing IOL samples with different materials (e.g., hydrophobic and hydrophilic) and designs (e.g., monofocal and toric) to better encompass types of IOLs in conventional use today. The results from this study demonstrate that significant changes are observed as temperatures are changed from room temperature (20°C) to slightly above body temperature (40°C). Findings indicate that evaluating optical properties at arbitrary temperatures could significantly affect the characterization of IOLs that are already near the tolerance thresholds.

Optimising biometry for best outcomes in cataract surgery

Biometry has become one of the most important steps in modern cataract surgery and, according to the Royal College of Ophthalmologists Cataract Surgery Guidelines, what matters most is achieving excellent results. This paper is aimed at the NHS cataract surgeon and intends to be a critical review of the recent literature on biometry for cataract surgery, summarising the evidence for current best practice standards and available practical strategies for improving outcomes for patients. With modern optical biometry for the majority of patients, informed formula choice and intraocular lens (IOL) constant optimisation outcomes of more than 90% within ± 1 D and more than 60% within ± 0.5 D of target are achievable. There are a number of strategies available to surgeons wishing to exceed these outcomes, the most promising of which are the use of strict-tolerance IOLs and second eye prediction refinement.