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Examples of acrylic polymers. PMA, poly(methacrylate); PMMA, poly(methyl methacrylate); PEMA, poly(ethyl methacrylate); poly-HEMA, poly(2-hydroxyethyl methacrylate). The hydroxyl group in poly-HEMA significantly increases this polymer's hygroscopy.
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Abstract An introduction to the history of intraocular lenses (IOLs) is given, leading up to modern hydrophobic examples. The roles of hydrophobicity, hygroscopy, materials chemistry, and edge design are discussed in the context of IOLs. The four major types of IOL materials are compared in terms of their chemistry and biocompatibility. An example...
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Context 1
... substituent groups attached directly to the backbone are added as a prefix to the ''acrylate'' base, while substituents attached further away from the backbone to the oxygen are separately designated. Note, for example, the differences between poly(methyl acrylate; PMA), poly(methyl methacrylate), and poly(ethyl methacrylate) are shown in Figure 3. When more than one type of monomer is polymerized together, the resulting plas- tic can be called a copolymer. ...
Context 2
... Their contact angle measurements do not necessarily correspond to their hygroscopy, as the surface of the lenses could be modified to alter their hydrophobicity. Hygroscopic acrylic polymers are made by modifying the side- chains connected to the methacrylate backbone of regular PMMA to contain hydroxyl components that attract water, most commonly poly(2-hydroxyethyl methacrylate), poly-HEMA, or just HEMA as shown in Figure 3. The folding of poly-HEMA chains depends significantly on the level of hydration, and so the physical and optical properties of the polymer change as a function of water content. ...
Similar publications
The first clinical application of intraocular lens (IOL) goes back to 1949 when Dr. Harold Ridley successfully implanted a PMMA IOL into an eye on 29 November 1949. This innovation is a big step forward for cataract surgery. With development of the IOL material and biocompatibility, more and more IOL types have been used in clinical ophthalmology....
Citations
... However, the unique attribute of this lens material is its water content. The Eternity IOL is a novel hydrophobic IOL, manufactured by combining the optimal features of conventional hydrophobic and hydrophilic polymers to create a 'glistening-free' lens [14,15]. Consequently, the water content of this IOL is 4%, which is higher than that of other hydrophobic IOLs. ...
In this retrospective case series, we investigated factors associated with posterior capsule aperture (PCA) reclosure following neodymium-yttrium aluminum garnet (Nd:YAG) laser posterior capsulotomy. The study encompassed patients who underwent cataract surgery with intraocular lens (IOL) implantation or a combined vitrectomy, cataract surgery, and IOL implantation between 2009 and 2022. PCA reclosure was observed in 22 eyes of 17 patients: 45% (10 eyes) underwent the triple procedure, and 55% (12 eyes) received cataract surgery with IOL implantation. In our clinic, 14% of patients were given IOLs with a 4% water content, while 73% (13 eyes) of those experiencing PCA reclosure had IOLs with a 4% water content. The mean interval between Nd:YAG capsulotomies was notably shorter than that between the initial cataract surgery and the first Nd:YAG laser capsulotomy. We also identified five stages of PCA reclosure progression. In conclusion, IOL water content may be linked to PCA reclosure, and the time to recurrence is shorter with each successive reclosure. Further research is needed to verify these findings and uncover additional contributing factors.
... The indentation elastic modulus (E IT ) and other mechanical properties such as the creep were obtained from the force displacement curve. The analysis of this curve is done automatically according to the ISO 14577 standard [10][11][12][13]. ...
IntroductionIntraocular lenses (IOL) should remain in the eye for life after implantation into the capsular bag during cataract surgery. The material must meet various requirements. It is crucial that the material has the best biocompatibility, and it should be flexible and soft for best possible implantation process but also sufficiently stable and stiff for good centering in the eye and posterior capsule opacification prevention.Methods
In this laboratory experiment, we used nano-indentation for the mechanical assessment of three hydrophobic acrylic (A, B, C), three hydrophilic acrylic (D, E, F), and one silicone (G) intraocular lens. We wanted to determine whether some react more sensitively to touching/handling than others. The indentation elastic modulus and the creep were obtained from the force displacement curve. For measuring penetration depth and testing of possible damage to the intraocular lenses, the samples were measured at room temperature. A 200-µm-diameter ruby spherical tipped indenter was used for all the tests. Indentations were made to three different maximum loads, namely 5 mN (milli Newton), 15 mN, and 30 mN and repeated three times.ResultsThe lowest penetration depth (12 µm) was observed with IOL B. However, IOL A, D, and F showed similar low penetration depths (20, 18, and 23 µm, respectively). Lenses C and E showed slightly higher penetration depths of 36 and 39 µm, respectively. The silicone lens (G) showed the greatest penetration depth of 54.6 µm at a maximum load of 5 mN. With higher maximal loads (15 and 30 mN) the penetration depth increased significantly. Lens C, however, showed the same results at both 15 and 30 mN with no increase of penetration depth. This seems to fit well with the material and manufacturing process of the lens (lathe-cut). During the holding time of 30 s at constant force all six acrylic lenses showed a significant increase of the creep (CIT 21–43%). Lens G showed the smallest creep with 14%. The mean indentation modulus (EIT) values ranged from 1 to 37 MPa. IOL B had the largest EIT of 37 MPa, which could be caused by the low water content.Conclusion
It was found that results correlate very well with the water content of the material in the first place. The manufacturing process (molded versus lathe-cut) seems to play another important role. Since all included acrylic lenses are very similar, it was not surprising that the measured differences are marginal. Even though hydrophobic materials with lower water content showed higher relative stiffness, penetration and defects can also occur with these. The surgeon and scrub nurse should always be aware that macroscopic changes are difficult to detect but that defects could theoretically lead to clinical effects. The principle of not touching the center of the IOL optic at any time should be taken seriously.
... The hygroscopic nature of a polymer changes depending on the temperature and ionic strength of the surrounding solution [22]. As water diffuses into the polymer due to equilibrium driving forces, discreetly visible vacuoles can develop [23]. However, why some IOLs are more prone to form glistenings than others is poorly disclosed in the literature. ...
... In fact, although water molecules can freely diffuse within the lens, they can be stuck in low-density regions, acting as cavities, with subsequent formation of water micro-droplets. Such a phenomenon is the already cited "glistenings" effect [23]. Baillif et al. [85] studied IOLs produced by different manufacturers made of the following six biomaterials: collamer, hydrophilic acrylic, hydrophobic acrylic, silicone, polymethylmethacrylate (PMMA), and heparin surface-modified PMMA (HSM-PMMA). ...
... The mechanical properties of polymers strongly change with temperature. In particular, they appear soft and are able to flow at temperatures higher than the so-called glass transition temperature (T g ) [23,40]. Instead, they appear hard for T < T g . ...
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.
... According to various authors, IOL glistening is influenced by the manufacturing process, the packaging system, the changes in temperature, the equilibrium water content, the IOL model, the IOL power, the breakdown of the blood-retina or blood-water barrier and the postoperative inflammation, especially in combined surgeries [3,6,8,9]. This glistening, or hydration-related phenomenon, has been observed in a variety of materials, including silicone, hydrogel and poly methyl methacrylate (PMMA) IOLs, but it is particularly common in hydrophobic acrylic IOLs [1,6,10,11]. ...
Purpose:
To propose a classification of the glistening in intraocular lenses (IOL) using swept-source optical coherence tomography (SS-OCT) by means of a simple, objective and reproducible method that allows the quantification of the presence and severity of glistening.
Methods:
A cross-sectional study on a sample of 150 eyes of 150 patients who underwent cataract surgery in at least 600 days before the exam and attended a routine examination. Each subject was examined by SS-OCT after pupil dilation, identifying the presence of glistening or hyperreflective foci (HRF) in the central area of the IOL. The degree of glistening was classified into four categories: 0: ≤5 HRF; 1: 6 to 15 HRF; 2: 16 to 30 HRF; and 3: >30 HRF. The intra and interobserver reproducibility (intraclass correlation coefficient, ICC) in the quantification and classification of the glistening were calculated. The correlation between the horizontal and vertical scan of the IOL was also assessed.
Results:
Glistening was present in the IOL in 42.7% of the patients. The mean number of HRF or glistening microvacuoles was 10.4 ± 26.2 (range 0 to 239). In total, 63.3% of the IOLs had a grade 0, 20% grade a 1, 6.7% grade a 2 and 10% a grade 3. The intraobserver and interobserver reproducibility were very high, both for the absolute quantification of the glistening (ICC ≥ 0.994) and for the severity scale (ICC ≥ 0.967). There was an excellent correlation in the quantification of the IOL glistening between the horizontal and vertical scans (R ≥ 0.834; p < 0.001).
Conclusions:
The use of SS-OCT makes it possible to identify, quantify and classify IOL glistening in a simple, objective and reproducible way. This technique could provide relevant information for the study of the glistening on IOLs.
... Water can be deposited in these free spaces, which promote the agglomeration and formation of water-filled microvacuoles ( Fig. 1). [4] In this work, the influence of higher amounts of different diacrylate crosslinkers on the reduction up to the prevention of glistening in a hydrophobic, aromatic copolymer is presented. This is accomplished by the reduction of the internal free volume. ...
... Influence of the crosslinker on the inhomogeneity of the polymer matrix during the swelling process, which can create free volume for the agglomeration of water. taken in modified form from [4] [5] *nima.heidary@chemie.uni-marburg.de; phone +49 6421 2825447; fax 49 6421 2825789; www.uni-marburg.de/fb15/ag-hampp ...
... Moreover,hydrophilic acrylic had insufficient uveal biocompatibility, as indicated by debris deposition on the surface of IOL [29]. Although the older generation of hydrophilic acrylic IOLs is connected to the calcification problem, the new generations of hydrophilic acrylic IOLs do not have this problem [32,33]. ...
... Hydrophobic acrylic IOLs are the most common type of lenses used worldwide [41], with AcrySof (Alcon Laboratories, Inc.) being the most widely used hydrophobic acrylic IOL. The AcrySof IOLs are made from hydrophobic acrylic that includes phenylethyl acrylate (PEA) and phenylethyl acetate (PEMA) copolymers and are cross-linked by butanediol diacrylate (BDDA) (Figure 2) [33]. The AcrySof IOLs have square optical edges, a water content lower than 0.5%, and a contact angle of 73°. ...
... [14]. Furthermore, hydrophobic acrylic is more likely to have glistening due to the formation of water pockets in the hydrophobic polymer [44] so increasing water content could reduce glistening in hydrophobic IOLs [33]. ...
... When an IOL is molded instead of lathe cut, the process allows gaps or vacuoles to form within the optic material, which then allow water to collect within the IOL, even after successful implantation. The resultant glistenings cause light to scatter as it enters the eye, which can result in reduced contrast sensitivity 31 . Glistenings develop over time, indicating that long-term outcomes are not fully known, and although some cases have resulted in IOL explantation, this is considered rare 32 . ...
To evaluate the long-term posterior capsule opacification (PCO) formation, and glistening rate of the HOYA Vivinex (XY1) IOL compared to Alcon AcrySof (SN60WF). In this prospective, multicentric, randomized, paired-eye, open-label study, we included 87 subjects that underwent cataract surgery with IOL implantation, with 67 patients completing the 3-year follow-up. The completer population consisted of 32 subjects implanted with XY1 and 35 implanted with SN60WF. Primary endpoints consisted of the evaluation of glistenings and measurement of PCO. Secondary outcomes included Best Corrected Distance Visual Acuity (BCVA), Contrast Acuity (CA), uncorrected visual acuities, subjective refraction, medical and lens complication rates, adverse events, and optical/visual symptoms. Follow-up visits occurred at 6-months, 1-, 2- and 3-years. At 3-years follow-up, mean PCO score was 0.121 ± 0.193 for eyes implanted with Vivinex versus 0.239 ± 0.463 for AcrySof (p = 0.026). The Vivinex IOL showed statistically significantly lower glistening occurrence through 3-years postoperatively (0.14 ± 0.26) compared to AcrySof (1.79 ± 1.43; p < 0.0001). Postoperative visual acuities improved from baseline in both IOL groups (p < 0.0001), and remained stable through the 3-year follow-up period. Eyes implanted with a HOYA Vivinex IOL exhibited significantly lower occurrence of glistening at 3-years versus Alcon AcrySof (p < 0.0001). Incidence of PCO was very low and comparable in both Vivinex and AcrySof eyes.
... Besides the drug delivery performance, selected formula of PUA and co-reactants (IBOMA and NVP) brought GAT-loaded IOL long-term preservation, outstanding optical properties, proper mechanical properties, along with good biocompatibility. Exhibited data of surface contact angle and MC of acrylic IOLs [64][65][66][67] suggested this novel IOL belongs to the hydrophilic kind. A drawback about drug-eluting hydrophilic acrylates (hydrogels) IOL was that the constantly diffusion of drug into soaking solution during storage reduced the drug amount [68]. ...
Postoperative endophthalmitis (POE) has been the most threatening complication after cataract surgery, which perhaps can be solved by the antibiotic-loaded intraocular lens (IOL). However, most drug-loaded IOLs demonstrate insufficient drug quantity, short release time, increased implantation-related difficulties or other noticeable drawbacks. To prevent POE and to address these deficiencies, a drug-loaded copolymer IOL, prepared from poly (urethane acrylate) prepolymer, isobornyl methacrylate (IBOMA), N-vinyl-2-pyrrolidone (NVP), Irgacure 819, RUVA-93, and gatifloxacin (GAT), was rapidly fabricated via photocuring and by using a 3D-printed mold. This composite displayed an outstanding and controllable GAT release behavior in vitro, a high light transmittance, and a moderate refractive index. Also, it demonstrated improved strain stress and elongation compared with the reference commercial acrylic IOL material. In vivo tests demonstrated satisfying released drug concentration at the early treatment stage. In vitro and in vivo studies further confirmed the remarkable bacterial inhibition and prevention of POE by the proposed IOL, which also displayed good biocompatibility. These findings suggested that the GAT-loaded IOL could be a promising implant to prevent and cure POE, also the proposed methods could inspire more designs for various medical applications.
... Whereas the AcrySof material composes phenylethyl acrylate (PEA) and phenylethyl methacrylate (PEMA) cross-linked with butanediol diacrylate (BDDA), in the Clareon material the PEMA monomer is replaced with the more hygroscopic monomer, 2-hydroxyethyl methacrylate (HEMA). Figure modified from Ref.8 . ...
Ophthalmic viscosurgical device (OVD) is used during intraocular surgery to protect ocular tissue. It requires complete removal from the eye by the end of surgery to avoid postoperative complications. This study compares the interaction of a cohesive OVD with two different intraocular lenses (IOLs) of different equilibrium water content. In this laboratory study on porcine cadaver eyes, the capsular bags and anterior chambers of each eye were filled with fluorescein-stained OVD. Following implantation of 10 IOLs each of Clareon CNA0T0 and AcrySof SN60WF (Alcon Laboratory, Fort Worth, USA) IOLs, the OVD was removed using the irrigation/aspiration mode. The OVD removal was timed and differences between the both IOL groups were compared. OVD removal time ranged from 18 to 40 s (mean ± SD, 26.4 ± 6.8 s) and from 16 to 39 s (mean ± SD, 23.6 ± 6.6 s) for eyes implanted with a CNA0T0 and a SN60WF IOL, respectively, without a statistically significant difference between the groups, P > 0.05. Cohesive OVD removal times were similar between the CNA0T0 and SN60WF groups. Surgeons should experience no differences regarding the interaction between cohesive OVDs and IOLs made from the new Clareon material compared to the established AcrySof material.
... The chemistry of IOL biomaterial is one of the main factors responsible for glistening. [6,7] Spinodal decomposition resulting from incompletely connected polymer chain, [8] thermal stress, [9] osmotic cavitation, [10] hydrophilic impurities, [11] aging hydrolysis, [12] and hydrolytic biodegradation [13,14] of copolymers are considered to be the possible physical mechanism of glistening formation and its subsequent optical effect. ...
... The IOL material in the present investigation was a copolymer of phenyl ethyl acrylate, phenyl ethyl methacrylate, 1-4-butanedediol diacrylate, and some cross-linkers. [8] Properties of Raman spectra of different polymers including HF IOL polymers have been documented by the researchers. Depending on the chemical composition of the material, the Raman bands appear at 800-1,800, 2,600-3,200, and at 32,00-3,700 cm -1 locations. ...
Purpose:
To study and interpret Raman spectra of six explanted acrylic hydrophobic foldable intraocular lenses (HFIOLs) with grade six microvacuoles and to understand the possible mechanism for microvacuole formation.
Methods:
Clinical data, slit-lamp photographs, and optical microphotographs of the explanted analytes were obtained. RS of the analytes were registered using a confocal Raman microscope (Lab RAM HR Evolution, Horiba Jobin Yvon) and Horiba Lab Space 6 Spectroscopy Suite software. Data were interpreted by identifying the functional group and fingerprint region of the spectra about the available literature.
Results:
IOLs were explanted for visual impairment after an average interval of 11.2 years following implantation. Each of the HFIOLs exhibited distinctive and identical Raman bands at the frequency range of 200-1,800, 2,600-3,000, and 3,200-3,700 cm-1 which were identified with those reported in the literature. The unique bands and peaks of the spectra were specific to the functional groups, its ring and other stretching variations, hydroxyl group, and water molecule. A spike at 1,640 cm-1 revealed the presence of monomer and indicated material bioincompatibility of the samples.
Conclusion:
Raman spectroscopy (RS) was found specific and an effective tool to detect the material change in the HFIOL and constituents of polymer biomaterial about microvacuole formation and also suggested modification and development of a more biocompatible and non-biodegradable polymer blend where RS could be a monitoring tool.
