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.

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.

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.

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.

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.].