Characterisation of Intraocular Lens Injectors.

In modern ophthalmic surgery, an intraocular lens (IOL) is commonly implanted into the patient's eye with an IOL injector. Many injectors are available, showing various technological differences, from the early manually loaded injector systems to the modern preloaded injectors. This review aims to give a concise overview of the defining characteristics of injector models and draws attention to complications that may occur during IOL implantation. One can differentiate injectors according to their preoperative preparation (manually loaded or preloaded), their implantation mechanism (push-type or screw-type or combined or automated), the size of the nozzle tip, the presence of an insertion depth control feature, and the injector's reusability. Potential complications are IOL misconfigurations such as a haptic-optic adhesion, adherence of the IOL to the injector plunger, an overriding plunger, uncontrolled IOL rotation, a trapped trailing haptic, or damage to the IOL. Additionally, during IOL implantation, the nozzle can become damaged with scratches, extensions, cracks, or bursts to the tip. While these complications rarely produce long-term consequences, manufacturers should try to prevent them by further improving their devices. Similarly, surgeons should evaluate new injectors carefully to ensure the highest possible surgical safety.

Reasons for explantation of phakic intraocular lenses and associated perioperative complications: cross-sectional explant registry analysis.

BACKGROUND: We discuss the safety, since their introduction, of phakic intraocular lenses (pIOLs) to correct refractive errors in healthy eyes. We investigated the reasons for pIOL explantation and the associated perioperative complications. METHODS: This retrospective, cross-sectional study included 69 pIOLs, explanted at a single tertiary center between July 2005 and March 2020: 34 angle-supported (G1), 28 iris-fixated (G2) and seven posterior chamber (G3) pIOLs. Case data including the reason for explantation was taken from the patient records. Intra- and postoperative complications were evaluated for an association with the pIOL. RESULTS: The mean duration in the eye was 10.4 (0.2-28) years. Cataractogenesis and subsequent surgery that required pIOL explantation was the reason in 42% of all cases. In 22%, cataract in combination with endothelial damage prompted explantation, with 26, 18 and 14% for G1, G2 and G3 respectively. The second most common reasons were corneal damage alone in the angle-supported group (26%), IOL subluxation in the iris-fixated group (18%), and photopic disturbance in the posterior chamber group (29%). In 68% of all explantations, the surgical course was unremarkable, while in the remaining cases perioperative complications were associated with the lens in 45.7%. CONCLUSION: Overall, the need for cataract surgery was the most common reason for pIOL explantation. Corneal complications were more frequent in the angle-supported pIOLs and their removal was associated with higher rates of complication compared to the other groups.

In-vitro assessment of a novel intraocular lens made of crosslinked polyisobutylene.

PURPOSE: To describe and analyse the particularities of the material and the optical quality of the first intraocular lens (IOL) (Eyedeal® lens) made of crosslinked polyisobutylene (xPIB). METHODS: We assessed the material quality using an accelerated ageing process (to provoke glistenings) and compared values with a control, AcrySof® lens. Using the sessile drop method, the contact angle of the new IOL was measured. Images of the lens surface were recorded by scanning electron microscopy (SEM). Optical quality was assessed by measuring the labeled power and modulation transfer function (MTF) using standard metrology equipment (OptiSpheric IOL PRO2). RESULTS: The Eyedeal® lens had an average glistening density result of 7.46 ± 3.78 MV/mm2 compared to the control AcrySof® whose glistenings number was 142.42 ± 72.47 MV/mm2. The contact angle was 97.2° whereas the angle of AcrySof material is between 73.3 ± 2.4° and 84.4 ± 0.1°. Using SEM, Eyedeal® lenses were examined and all appeared to be comparable to modern IOLs made of acrylic materials. The power and MTF values were normal and conformed to ISO standards. CONCLUSIONS: In the laboratory, the new Eyedeal® lens showed equivalence to current hydrophobic- or hydrophilic-acrylic lens models. It showed superiority in its glistening density result compared to the control lens.

Physicochemical Properties of Explanted Silicone Oil After Use as an Intraocular Tamponade.

PURPOSE: We studied the effects of exposure to biological media within the eye, such as contamination with lipophilic and amphiphilic substances, on the physicochemical parameters of silicone oil used as an intraocular tamponade. METHODS: We removed silicone oil with visible emulsification from 15 patients and measured each sample for shear viscosity and surface tension. We induced in vitro emulsification with balanced salt solution. Using the zeta-potential, we evaluated the emulsion droplet's electrochemical stability. We repeated all experiments in a control group of unused oil. Electrochemical stability and viscosity were additionally measured in oils with high-molecular-weight components. RESULTS: We recovered silicone oils implanted between 30 and 506 days (mean, 196 days). Viscosity did not differ between explanted and control groups. Surface tension and zeta potential remained unchanged (P = 0.61 and P = 0.84, respectively). All oils showed a significant correlation of viscosity with temperature (P < 0.01 for all). Oils with added high-molecular-weight components showed a lower emulsion stability. CONCLUSIONS: Prolonged contact to hydrophilic biological media does not alter high-viscosity silicone oil's physicochemical parameters. During typical durations of intraocular use, lipophilic and amphiphilic molecules had no deleterious effect. The addition of high-molecular-weight components might decrease the silicone oil's electrochemical emulsion stability, possibly easing the confluence of emulsion droplets. TRANSLATIONAL RELEVANCE: Although the physicochemical parameters of silicone oils are not altered after clinically relevant durations within the eye, emulsion stability significantly differs between oil types.

Quantification of the In Vitro Predisposition to Glistening Formation in One Manufacturer's Acrylic Intraocular Lenses Made in Different Decades.

INTRODUCTION: Foldable hydrophobic acrylic intraocular lenses (IOLs) are prone to develop a long-term postoperative material change called glistenings. The aim of this study was to investigate the changes in the predisposition for glistening formation in one type of hydrophobic acrylic IOL material from its introduction to the present day. METHODS: In a laboratory setup, an in vitro model was used to induce glistenings in hydrophobic acrylic IOLs manufactured by one company (Alcon, Fort Worth, TX, USA) in different years: 23 1990s-manufacture hydrophobic acrylic three-piece IOLs (MA30BA/MA60AC) that were explanted in 1996 and 1997, and five of each of the newer AcrySof IOL models (MA60AC, SA60AT, TFNT00 and SN60WF) from 2014 to 2017. Furthermore, five Clareon (SY60WF) IOLs were put through the same accelerated aging procedure. The number of microvacuoles per square millimeter (MV/mm2) was determined in the central part of each IOL optic and compared between the groups. RESULTS: The mean number of MV was highest in the 1990s-manufacture Alcon acrylic IOLs, with 1289 (± 738) MV/mm2. The number decreased to 650 (± 101), 192 (± 105), 175 (± 112) and 47 (± 26) for MA60AC, SA60AT, TFNT00 and SN60WF, respectively. The lowest count was obtained in the Clareon group, with 1 (± 1) MV/mm2. CONCLUSIONS: A high number of glistenings was induced in the explanted IOLs from the 1990s. The propensity for glistening formation decreased considerably after that decade and now in current use. Even though in vitro glistening formation in today's AcrySof material was low, the Clareon material was essentially glistenings-free.

Variation in intraocular lens calcification under different environmental conditions in eyes with supplementary sulcus-supported lenses.

PURPOSE: Analysis of explanted intraocular lenses (IOLs) from pseudophakic eyes with supplementary sulcus-supported IOLs. METHODS: In this laboratory investigation, ten supplementary and capsular bag IOLs were analyzed. All lenses were received between January 2012 and March 2018. Explants were examined morphologically with histological and electron microscopic techniques and patients' medical history was evaluated. Additionally, we used a technique new to this field: Transmission Electron Microscopy and electron diffraction pattern analysis was performed to investigate the structure of the opacifying crystals in detail. RESULTS: Eleven lenses were explanted due to IOL opacification from seven polypseudophakic eyes: In three cases the supplementary lens calcified, in three cases the capsular bag IOL (both lenses analyzed) and in one case both IOLs (only the supplementary was received). Additional surgical procedures and comorbidities included pars plana vitrectomy or Descemet stripping endothelial keratoplasty and diabetes mellitus. For each opacified lens, a varying layer of a Calcium phosphate beneath the optic surface was apparent. Crystal characterization revealed its composition to be Hydroxyapatite. CONCLUSIONS AND IMPORTANCE: We report on a series of secondary calcification in lenses explanted from polypseudophakic eyes. In some cases, calcification occurred in the capsular bag lens, in other cases in the supplementary lens, or in both. The severity of the morphological change could be related to the comorbidities and the presence of surgery subsequent to the lens implantations. Detailed morphology of the opacifying crystals was revealed.