THE NOVEL USE OF HIGH-FLOW POLYIMIDE CANNULAS TO IMPROVE SILICONE OIL INJECTABILITY IN VITREORETINAL SURGERY.

PURPOSE: The injection of high-viscosity silicone oil lengthens injection time. New polyimide cannulas offer a greater inner diameter than conventional metal cannulas at the same gauge. We compared the injection time for polyimide and metal cannulas at 23 G for a variety of silicone oils including a 12,500-mPas prototype oil. METHODS: In this laboratory study, injection time was measured three times per cannula and per oil. Warming the oil before injection to up to 42°C was also evaluated. Finally, the feasibility of polyimide cannulas was tested in vitrectomized porcine eyes. RESULTS: The 23-G polyimide cannula mostly decreased injection times. The time to inject 5 mL of Siluron Xtra and Siluron 5000 decreased by 6:02 (76.9%) minutes (483 vs. 121 seconds) and 12:01 (74.7%) minutes (973 vs. 252 seconds), respectively. Although the 23-G metal cannula failed to inject 12,500 mPas oil, 5 mL was injected in 10:21 minutes using the polyimide cannula. Prewarming Siluron 5000 to 42°C lowered the injection time by 9.0% and by 12.1% when using the metal or polyimide cannula, respectively. CONCLUSION: Polyimide cannulas allow a clinically relevant decrease in injection time. They may not only shorten surgery time but could also ease the use of next-generation ultra-high-viscosity silicone oils. Prewarming silicone oil leads to decreased injection times.

Glistening formation in a new hydrophobic acrylic intraocular lens.

BACKGROUND: The formation of fluid-filled microvacuoles, termed glistenings, is a common complication of intraocular lenses (IOLs) made from hydrophobic acrylate. Using our well-established in-vitro laboratory method, we evaluated a new IOL material's resistance to glistening formation. METHODS: An in-vitro stress test for glistening induction was performed on 20 samples of hydrophobic acrylic IOLs: ten of the new Eyecryl ASHFY600 (Biotech Vision Care, Ahmedabad, India) compared with ten samples of AcrySof IQ SN60WF (Alcon, Fort Worth, USA). The number of microvacuoles per square millimetre (MV/mm2) was evaluated in five sections of each IOL. The results for each model were compared and rated on a modified Miyata Scale for grading glistening severity. RESULTS: In all cases, glistening number was higher in the central section of the IOL optic than in the periphery. Mean number of MV/mm2 was highest in the central part of the AcrySof IQ SN60WF, with 41.84 (±27.67) MVs/mm2. The lowest number of glistenings was found in the five sections of the Eyecryl ASHFY600 with 0.52 (±0.24) MVs/mm2. Mean value of the Eyecryl ASHFY600 IOL, using the Miyata Scale, was Zero. CONCLUSION: In this in-vitro laboratory study, the new hydrophobic acrylic IOL showed a high resistance to microvacuole formation. Results from this in-vitro study suggest that glistening numbers will be low in clinical use in the Eyecryl ASHFY600.

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.

Material Analysis of Explanted Calcified Silicone Intraocular Lenses in Association with Asteroid Hyalosis.

INTRODUCTION: The aim of this study was to analyze posterior surface opacification in explanted silicone intraocular lenses (IOLs) with clinicopathologic correlation to asteroid hyalosis. METHODS: In a laboratory setup, 12 explanted silicone IOLs underwent laboratory analyses, including light microscopy, scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy for elemental composition (EDX). Relevant clinical data were obtained for each case, including gender, age at IOL implantation, dates of implantation and explantation, as well as history of neodymium-dopped yttrium aluminum garnet (Nd:YAG) laser treatments or other opacification removal attempts. High-resolution optical coherence tomography (OCT) images were obtained in vitro with an anterior segment OCT device (Anterion, Heidelberg Engineering, Heidelberg, Germany). RESULTS: Calcification located at the posterior optic surface of each lens was identified through SEM and EDX analyses, revealing deposits composed of hydroxyapatite. In all cases, IOL polishing using Nd:YAG laser had been attempted prior to IOL exchange. The clinical functional data showed that this type of IOL opacity led to increase in straylight and subjective symptoms of glare. CONCLUSIONS: Silicone IOLs can develop posterior surface calcification in eyes with asteroid hyalosis. There are mechanical techniques of cleaning the IOL surface but in many cases, IOL explantation is the only sustainable way to reduce the patients' straylight levels and glare symptoms. Due to the risk of posterior surface calcification, silicone IOL implantation should be avoided in eyes with asteroid hyalosis.

Ophthalmic viscosurgical device interaction with two hydrophobic acrylic intraocular lenses of different equilibrium water content.

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.

Intravitreal Application: Physicochemical Properties of Drugs Dissolved in Silicone Oils of Different Density in Comparison to the Porcine Vitreous Body.

Silicone oil endotamponades provide a reservoir for drugs in the eye. Following vitrectomy surgery to treat retinal detachments, extensive diabetic retinopathy or endophthalmitis, they can be used as long-term lipophilic depots. This study aimed to investigate the physicochemical properties of intravitreally applied drugs of different lipophilicity, namely vancomycin, ceftazidime and voriconazole. For this purpose, an in vitro model of the silicone-oil-filled eye compared to porcine vitreous bodies (PVBs) was used. In a glass container, either light or heavy silicone oil or PVB was set into equilibrium with an aqueous fluid. Vancomycin, voriconazole and ceftazidime were added in concentrations commonly applied in clinical practice. The time course of the concentration of the drugs was determined in the hydrophilic phase for up to 24 h. With silicone oil present, the concentrations of vancomycin, voriconazole and ceftazidime were elevated in the aqueous humor when compared to the vitreous body (p < 0.001 for all drugs). With increasing lipophilicity, higher concentrations of the drug dissolved in silicone oil after 24 h (52.7%, 49.1% and 34.3% for vancomycin, ceftazidime and voriconazole, respectively). While no difference between lighter- and heavier-than-water silicone oil was apparent for vancomycin and ceftazidime (p = 0.17 and p = 0.72), voriconazole dissolved significantly better in the heavier-than-water silicone oil (p = 0.002). A higher-than-expected percentage of the glycopeptide vancomycin dissolved in the porcine vitreous body, possibly due to protein binding. In conclusion, silicone oils influence the drug concentration and distribution of intravitreally applied drugs depending on their lipophilicity. The addition of F6H8 used to create heavy silicone oils attenuates these effects for lipophilic drugs. Knowledge of the distribution of these intravitreally applied drugs is crucial to ensure the desired anti-infectious effect.

Quantitative evaluation of microvacuole formation in five intraocular lens models made of different hydrophobic materials.

In this laboratory study, we assessed the resistance to microvacuole (glistening) formation in hydrophobic intraocular lenses (IOLs). Glistenings were induced in five lenses each of five different hydrophobic acrylic IOL models, using an established in vitro laboratory model: 800C (Rayner, Worthing, UK), AcrySof SN60WF (Alcon, Fort Worth, USA), Tecnis ZCB00 (Johnson & Johnson Vision, Santa Ana, USA), Vivinex XY1 (Hoya, Tokyo, Japan) and CT Lucia 611P (Zeiss, Oberkochen, Germany). We evaluated the number of microvacuoles per square millimeter (MV/mm2) in the central part of each IOL. Results were analyzed statistically, and mean glistening numbers were ranked, with the highest in the SN60WF which had 66.0 (±45.5) MVs/mm, followed by the 611P with 30.7 (±8.4) MVs/mm2. The 800C and XY1 showed comparable values of 2.0 (±3.6) and 2.7 (±2.4) MVs/mm2, respectively. ZCB00 had the lowest number with 0.9 (±0.6) MVs/mm2. This study shows that the resistance to glistening formation differs depending on the hydrophobic acrylic copolymer composition of the IOL material. Some IOLs from current clinical use are still prone to develop glistenings whereas others, including the ZCB00, 800C and XY1 show high resistance to microvacuole formation.

Injection time related to intraocular pressure using a CO2 driven preloaded injector: An experimental laboratory study.

PURPOSE: Experimental study to measure the intraocular lens (IOL) injection time and injection speed at different intraocular pressure (IOP) settings when using the AutonoMe® injector. METHODS: In this experimental study, following phacoemulsification in porcine cadaver eyes, a trocar was inserted at pars plana with a connected infusion and IOPs of 20, 50 and 80 mmHg were generated by altering the infusion height. Twelve CO2 gas-driven injectors were used to implant an IOL via a corneal incision of 2.2 mm. For each IOP setting, the duration of the IOL injection and the injection speed was measured by analyzing a video recording of the procedure. RESULTS: The mean ±SD injection time (seconds) was 4.47±0.50 at 20 mmHg, 4.98±0.55 at 50 mmHg and 5.47±0.20 at 80 mmHg. The mean ±SD injection speed (millimeters per seconds) was 1.36±0.15 at 20 mmHg, 1.22±0.14 at 50 mmHg and 1.10±0.04 at 80 mmHg. There was a significant (p<0.05) difference between the 20 and 80 mmHg groups in mean injection duration and injection speed. CONCLUSION: The CO2 gas driven injector allows a safe IOL injection even at elevated IOP. Although the implantation time is slightly extended at higher IOPs, this does not seem to be clinically relevant. No IOL damage was observed at these pressure settings.

A Novel Approach for Assessing Visual Impairment Caused by Intraocular Lens Opacification: High-Resolution Optical Coherence Tomography.

PURPOSE: To quantify in vitro straylight induced by intraocular lens (IOL) localized opacification using an anterior segment optical coherence tomography (OCT) device. DESIGN: Laboratory investigation. METHODS: We obtained high-resolution OCT cross-section images of 44 explanted IOLs using a new in vitro application for an anterior segment OCT device, the Anterion (Heidelberg Engineering, Heidelberg, Germany). In 24 cases, the reason for IOL explantation was a centrally localized opacification, the sequela of a secondary ocular surgery. As a control, we used 20 IOLs removed after an IOL (sub-)luxation. Using image analysis, we found a threshold area value representing a metric for the amount of opacification in a region of interest in the IOL's central optic. We used a modified C-Quant straylight meter (Oculus, Wetzlar, Germany) to quantify light scattering. We derived a linear regression from calculating the correlation between the amount of opacification and straylight. RESULTS: We visualized different amounts of IOL opacification using the OCT device. The opacified lenses showed a mean threshold area of 6.7% ± 3.3% and mean straylight was 95.1 ± 75.6 deg2/sr. The clear group's mean threshold area was 2.0% ± 0.8% and 5.0 ± 3.4 deg2/sr mean straylight. Straylight correlated statistically significantly with the threshold area, with a correlation coefficient of R2 = 0.80, P < .001. CONCLUSIONS: This high-resolution OCT imaging technique can be used to visualize IOL opacities. The amount of opacification correlated well with the straylight induced by the lens. Anterior segment OCT imaging might be used in the future as a tool for predicting the extent of visual impairment and aid clinicians to quantify patients' complaints.

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.

Impact of Primary Calcification in Segmented Refractive Bifocal Intraocular Lenses on Optical Performance Including Straylight.

PURPOSE: To describe and analyze the impact of calcification on the optical quality of segmented refractive bifocal intraocular lenses (IOLs). METHODS: Eight segmented refractive bifocal IOLs made of hydrophilic acrylic were explanted from 8 patients due to opacification (and one opacified IOL that was not explanted) and analyzed in a cross-sectional study with laboratory analysis. Nine cases comprised three IOL models: LS-313 MF30 (5 cases), LS-312 MF30 (3 cases), and LS-313 MF15 (1 case). Material analysis with scanning and transmission electron microscopy confirmed IOL calcification. Measurements of modulation transfer function (MTF) and straylight permitted assessment of the IOL optical quality. Values were compared to a control lens. RESULTS: Except for one case of Nd:YAG (neodymium:yttrium-aluminum-garnet) capsulotomy, there was no secondary surgical procedure in the patients' histories. Eight of nine patients reported deteriorated visual quality, ultimately requiring IOL exchange. Material evaluation revealed fine granules of a calcium phosphate. Despite calcification, all but one lens still showed two distinct foci on the MTF measurements. Straylight values were higher than in a cataractous lens (33.1 deg2/sr) in all cases, with an average value of 170.1 ± 71.5 deg2/sr. CONCLUSIONS: Optical quality assessment showed that IOL calcification had a small effect on the MTF of segmented refractive bifocal lenses but a large impact on the straylight levels. Accordingly, in the clinical case, straylight levels were elevated. [J Refract Surg. 2020;36(1):20-27.].

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.