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Lens refilling and endocapsular polymerization of an injectable intraocular lens: In vitro and in vivo study of potential risks and benefits

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Endocapsular cataract removal and injection of a liquid artificial lens has several advantages, including restitution of accommodation, small corneoscleral incision, a more physiological position of the intraocular lens, and a reduced rate of secondary opacification. Our technique consists of bimanual phacofragmentation followed by injection of a fluid monomeric material that can be polymerized inside the capsular bag by short light exposure. Our study assessed the potential risks of the technique (e.g., heat damage to ocular tissue, light damage to the retina) and investigated the technique in vivo. We performed in vitro experiments on porcine cadaver eyes and an in vivo study on 15 rabbits. After a clinical follow-up of at least 12 weeks, the eyes were investigated histopathologically. During the polymerization process, the highest temperature measured at the posterior lens capsule was 45.1 degrees Celsius for a few seconds. The measured irradiance (0.065 watts per cm2) and the risk of photochemical damage to the retina during 20 seconds of polymerization were comparable to that caused by 1.5 minutes of standard coaxial illumination with the operating microscope. In vivo there were no serious inflammatory reactions except in four cases in which there had been intraoperative problems. The rate of secondary opacification appeared less than in conventional intraocular lens implantation in rabbits, especially when the capsule refilled completely. Retinal damage could not be detected histopathologically. In conclusion, refilling techniques may be successful once appropriate refilling materials become available.
... In order to overcome the long polymerization time of silicon containing polymers, some researchers proposed photopolymerization compounds. Hettlich's research team developed a liquid monomer, which can be polymerized in situ by exposure to blue light with a wavelength of 400-500 nm in only 20 seconds [30][31][32]. Moreover, the substance itself had the characteristics of contact inhibition, which significantly reduced the incidence of the rate of secondary opacification in rabbits, especially when the capsule refilled completely [31]. ...
... Hettlich's research team developed a liquid monomer, which can be polymerized in situ by exposure to blue light with a wavelength of 400-500 nm in only 20 seconds [30][31][32]. Moreover, the substance itself had the characteristics of contact inhibition, which significantly reduced the incidence of the rate of secondary opacification in rabbits, especially when the capsule refilled completely [31]. However, the refractive index was 1.532, and there was no elasticity after polymerization, so it was abandoned. ...
... Hettlich et al. made a smaller corneal incision and used a bimanual phacofragmentation through two opposing 1.0 mm corneal incisions and two 1.0 mm diameter peripheral anterior capsule openings. ey removed the capsular contents completely by using curved needles and suction tips [30][31][32]43] (Figure 2). During the operation of Han et al., a 2.5 mm clear corneal incision at 12 : 00 was made for phacoemulsification [33,34]. ...
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The ultimate goal of cataract surgery is to restore the accommodation while restoring distance visual acuity. Different kinds of accommodative intraocular lens (IOLs) and surgical techniques have been suggested to apply during the surgery, but they showed poor postoperative accommodation. It is possible to achieve this goal by refilling the lens with an injectable polymer. We present a summary of the existing materials, methods, results, and some obstacles in clinical application that remain of lens refilling for restoration of accommodation. Two main problems have restricted the clinical application of this technique. One was the formation of postoperative secondary capsule opacification and the other was the different accommodative power after surgery.
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