Changes in Anterior Segment Morphology and Intraocular Pressure after Cataract Surgery in Non-glaucomatous Eyes.

BACKGROUND: It is known that cataract extraction is associated with a significant reduction in intraocular pressure, especially in narrow angled eyes; however, the modifications of anterior segment parameters associated with this phenomenon have still not been completely defined. The purpose of this study was to evaluate changes in anterior segment anatomy and intraocular pressure after cataract surgery in non-glaucomatous eyes. METHODS AND MATERIAL: This retrospective case series study included 64 eyes of 64 consecutive patients who underwent phacoemulsification with intraocular lens implantation. Anterior segment parameters and intraocular pressure were assessed and compared before and 6 months after surgery. Anterior segment imaging was performed using Casia SS-1000 anterior segment optical coherence tomography (Tomey, Nagoya, Japan). Anterior segment measurements included anterior chamber depth, anterior chamber width, anterior chamber volume, angle opening distance at 500 µm anterior to the scleral spur, angle recess area 750 µm from the scleral spur, lens vault, trabecular iris space area at 500 µm from the scleral spur, and trabecular iris angle at 500 µm from the scleral spur. Intraocular pressure was measured using the Goldmann applanation tonometer (Model AT 900 C/M, Haag-Streit, Bern, Switzerland). Anterior segment parameters and the relationship of changes in intraocular pressure were also evaluated. RESULTS: All anterior segment parameters increased significantly after surgery (p < 0.05). Both angle opening distance at 500 µm anterior to the scleral spur and anterior chamber depth changes were positively correlated with the preoperative lens vault. The mean intraocular pressure significantly decreased from 14.91 mmHg (± 2.8 SD) to 12.91 mmHg (± 3.13 SD) (p < 0.001). Changes in intraocular pressure correlated negatively with values for the width of the preoperative anterior chamber (r = - 0.533; p = 0.001). CONCLUSION: Cataract surgery led to significant widening of the anterior chamber angle and lowering of intraocular pressure. Further investigations are needed to better understand whether anterior chamber width may be a new independent predictive factor for reduction in postoperative intraocular pressure.

Humidity Responsive Reflection Grating Made by Ultrafast Nanoimprinting of a Hydrogel Thin Film.

The response time of state-of-the-art humidity sensors is ≈8 s. A faster tracking of humidity change is especially required for health care devices. This research is focused on the direct nanostructuring of a humidity-sensitive polymer thin film and it is combined with an optical read-out method. The goal is to improve the response time by changing the surface-to-volume ratio of the thin film and to test a different measurement method compared to state-of-the-art sensors. Large and homogeneous nanostructured areas are fabricated by nanoimprint lithography on poly(2-hydroxyethyl methacrylate) thin films. Those thin films are made by initiated chemical vapor deposition (iCVD). To the author's knowledge, this is the first time nanoimprint lithography is applied on iCVD polymer thin films. With the imprinting process, a diffraction grating is developed in the visible wavelength regime. The optical and physicochemical behavior of the nanostructures is modeled with multi-physic simulations. After successful modeling and fabrication a first proof of concept shows that humidity dependency by using an optical detection of the first diffraction order peak is observable. The response time of the structured thin film results to be at least three times faster compared to commercial sensors.

Study on Porosity in Zinc Oxide Ultrathin Films from Three-Step MLD Zn-Hybrid Polymers.

Deriving mesoporous ZnO from calcinated, molecular layer deposited (MLD) metal-organic hybrid thin films offers various advantages, e.g., tunable crystallinity and porosity, as well as great film conformality and thickness control. However, such methods have barely been investigated. In this contribution, zinc-organic hybrid layers were for the first time formed via a three-step MLD sequence, using diethylzinc, ethanolamine, and maleic anhydride. These zinc-organic hybrid films were then calcinated with the aim of enhancing the porosity of the obtained ZnO films. The saturation curves for the three-step MLD process were measured, showing a growth rate of 4.4 ± 0.2 Å/cycle. After initial degradation, the zinc-organic layers were found to be stable in ambient air. The transformation behavior of the zinc-organic layers, i.e., the evolution of the film thickness and refractive index as well as the pore formation upon heating to 400, 500, and 600 °C were investigated with the help of spectroscopic ellipsometry and ellipsometric porosimetry. The calculated pore size distribution showed open porosity values of 25%, for the sample calcinated at 400 °C. The corresponding expectation value for the pore radius obtained from this distribution was 2.8 nm.

Deposition of Ion-Conductive Membranes from Ionic Liquids via Initiated Chemical Vapor Deposition.

In this study, liquid droplets of 1-allyl-3-methylimidazolium dicyanamide have been processed by initiated chemical vapor deposition (iCVD) with a cross-linked polymer film consisting of (hydroxyethyl)methacrylate and ethylene glycol dimethacrylate to develop free-standing, ion-conductive membranes. We found that the obtained films are solids and have a conductivity of up to 18 ± 6 mS/cm, associated with the negatively charged counterion, indicating no loss of conductivity, compared to the ionic liquid in the liquid state. The membranes were conductive within a large process window and in air, thanks to the fact that the iCVD process does not affect the mobility of the anion in the ionic liquid. Furthermore, we demonstrate that varying the deposition conditions can influence the homogeneity and conductivity of the resulting membranes. The promising results of this study represent an important stepping stone on the way to novel ion-conductive membranes.

Initiated Chemical Vapor Deposition of Crosslinked Organic Coatings for Controlling Gentamicin Delivery.

A coating consisting of a copolymer of methacrylic acid and ethylene glycol dimethacrylate was deposited over a gentamicin film by initiated chemical vapor deposition with the aim of controlling the drug release. Gentamicin release in water was monitored by means of conductance measurements and of UV-vis Fluorescence Spectroscopy. The influence of the polymer chemical composition, specifically of its crosslinking density, has been investigated as a tool to control the swelling behavior of the initiated chemical vapor deposition (iCVD) coating in water, and therefore its ability to release the drug. Agar diffusion test and microbroth dilution assays against Staphylococcus aureus and Pseudomonas aeruginosa on cellulose coated substrates confirmed that the antibacterial activity of the drug released by the coating was retained, though the release of gentamicin was not complete.

Polarized Raman spectroscopy to elucidate the texture of synthesized MoS2.

Texture has a significant impact on several key properties of transition-metal dichalcogenides (TMDs) films. Films with in-plane oriented grains have been successfully implemented in nano- and opto-electronic devices, whereas, films with out-of-plane oriented material have shown excellent performance in catalytic applications. It will be demonstrated that the texture of nanocrystalline TMD films can be determined with polarized Raman spectroscopy. A model describing the impact of texture on the Raman response of 2D-TMDs will be presented. For the specific case of MoS2, the model was used to quantify the impact of texture on the relative strength of the A1g and E12g modes in both the unpolarized and polarized Raman configuration. Subsequently, the capability to characterize texture by polarized Raman was demonstrated on various MoS2 films grown by atomic-layer deposition (ALD) and validated by complementary transmission electron microscopy (TEM) and synchrotron based 2D grazing-incidence X-ray diffraction (GIXD) measurements. This also revealed how the texture evolved during ALD growth of MoS2 and subsequent annealing of the films. The insights presented in this work allow a deeper understanding of Raman spectra of nanocrystalline TMDs and enable a rapid and non-destructive method to probe texture.

Interlink between Tunable Material Properties and Thermoresponsiveness of Cross-Linked Poly(N-vinylcaprolactam) Thin Films Deposited by Initiated Chemical Vapor Deposition.

In this contribution, we report on the thin-film synthesis of a novel thermoresponsive polymer, namely, poly(N-vinylcaprolactam) cross-linked by di(ethylene glycol)divinyl ether [p(NVCL-co-DEGDVE)] by initiated chemical vapor deposition (iCVD). Its transition between swollen and shrunken states in film thickness and the corresponding lower critical solution temperature (LCST) was investigated by spectroscopic ellipsometry in water. Water contact angle measurements and nano-indentation experiments reveal that the transition is accompanied by a change in wettability and elastic modulus. The amount of cross-linking was used to tune the thermoresponsive behavior of the thin films, resulting in higher swelling and LCST, increased surface rearrangement, and lower stiffness for less cross-linked polymers. For the first time, the filament temperature during iCVD synthesis was used to vary the chain length of the resulting polymeric systems and, thus, the position of their thermoresponsive transition. With that, swelling of up to 250% compared to the dry thickness and transition temperatures ranging from 16 to 40 °C could be achieved.

Intraocular Pressure Changes during Femtosecond Laser-Assisted Cataract Surgery: A Comparison between Two Different Patient Interfaces.

PURPOSE: The aim of this retrospective cohort study was to evaluate intraocular pressure (IOP) changes during femtosecond laser-assisted cataract surgery (FLACS) using two different patient interface systems. METHODS: 116 eyes of 116 patients scheduled for cataract surgery were divided into 2 groups: group 1 (61 eyes) and group 2 (55 eyes) underwent FLACS using Catalys Laser with fluid interface (liquid optics interface, LOI) and LenSx Laser with curved interface and soft contact lens (SoftFit), respectively. IOP was assessed using a portable rebound tonometer (Icare®) preoperatively, after docking, immediately after surgery, at one and seven days postoperatively. RESULTS: In group 1, the mean IOP (±SD) was 14.1 ± 0.4 mmHg before surgery, 33.2 ± 1.1 mmHg after docking, and 21.4 ± 0.9 mmHg immediately after surgery. In group 2, the mean IOP was 13.8 ± 0.4 mmHg before surgery, 24.2 ± 1.4 mmHg after docking, and 20.2 ± 1.2 mmHg immediately after surgery. After the docking procedure, a statistically significant increase in IOP from the baseline was found in both groups (p < 0.001). Moreover, no statistically significant difference in IOP measured at 1 and 7 days postoperatively was observed compared with the preoperative values (p > 0.05) using both laser platforms. No intraoperative and postoperative complications were observed. CONCLUSIONS: FLACS suction phase resulted in a transient increase of IOP in both groups, especially with the LOI system, and it is probably related to the greater pressure of a suction ring and suction generated through the vacuum, independently from the effect of femtosecond laser itself.

Mesoporous ZnO thin films obtained from molecular layer deposited "zincones".

The delivery of porous ZnO thin films represents a challenge due to the low porosity achievable by conventional thin film deposition methods. In this contribution, the synthesis of mesoporous ZnO thin films is demonstrated through calcination in air of hybrid Zn-based polymers (zincone) obtained by molecular layer deposition (MLD). The calcination process was followed as a function of temperature using X-ray reflectivity and diffraction, together with spectroscopic ellipsometry. Temperature ranges were identified for the removal of the organic ligands (120 °C) and ZnO crystallization (340 °C). The total porosity and open porosity were also determined by ellipsometric porosimetry (EP) and grazing incidence small-angle X-ray scattering (GISAXS). The calcination temperature was identified as a control parameter for obtaining different (open) porosity contents and pore size distributions (PSDs). Open porosity values of 12.6% and 19.6% were obtained by calcining the zincones up to 600 °C and 400 °C, respectively. Open PSDs with a mean value of 3.2 nm (400 °C) and 4.6 nm (600 °C) were obtained. The formation of larger slit-shaped pores was demonstrated at higher temperatures, due to the growth and coalescence of ZnO crystallites.

On the transformation of "zincone"-like into porous ZnO thin films from sub-saturated plasma enhanced atomic layer deposition.

The synthesis of nanoporous ZnO thin films is achieved through annealing of zinc-alkoxide ("zincone"-like) layers obtained by plasma-enhanced atomic layer deposition (PE-ALD). The zincone-like layers are deposited through sub-saturated PE-ALD adopting diethylzinc and O2 plasma with doses below self-limiting values. Nanoporous ZnO thin films were subsequently obtained by calcination of the zincone-like layers between 100-600 °C. Spectroscopic ellipsometry (SE) and X-ray diffraction (XRD) were adopted in situ during calcination to investigate the removal of carbon impurities, development of controlled porosity, and formation and growth of ZnO crystallites. The layers developed controlled nanoporosity in the range of 1-5%, with pore sizes between 0.27 and 2.00 nm as measured with ellipsometric porosimetry (EP), as a function of the plasma dose and post-annealing temperature. Moreover, the crystallinity and crystallite orientation could be tuned, ranging from a powder-like to a (100) preferential growth in the out-of-plane direction, as measured by synchrotron-radiation grazing incidence XRD. Calcination temperature ranges were identified in which pore formation and subsequent crystal growth occurred, giving insights in the manufacturing of nanoporous ZnO from Zn-based hybrid materials.

Controlled drainage of subretinal fluid during scleral buckling surgery for rhegmatogenous retinal detachment: the pigment stream sign.

PURPOSE: To describe the macroscopic characteristics of the subretinal fluid (SRF) and its spilling modality during evacuative puncture in scleral buckling (SB) surgery for rhegmatogenous retinal detachment. METHODS: We retrospective reviewed all the SB surgeries performed over a period of 26 months at the University Eye Clinic of Trieste, Italy. We selected a cohort of 102 patients in which SRF drainage by means of evacuative puncture was performed. A high-definition video was recorded during the whole duration of the procedures, and the macroscopic characteristics of the SRF leakage were assessed. RESULTS: Pigmented dark-brownish deposits spilling in the fluid outcoming from the evacuative puncture was observed during the surgeries. In all cases, this macroscopic feature was detected during the late phases of the drainage. Moreover, indirect ophthalmoscopic evaluation showed the almost complete SRF drainage and a flattened retina at that moment. CONCLUSIONS: The pigment stream sign, easily detectable by the surgeon, allows to understand, during the evacuative puncture, when the SRF has been drained almost completely and that the drainage procedure is therefore close to the end.

Thickness-Dependent Swelling Behavior of Vapor-Deposited Smart Polymer Thin Films.

In this contribution, the temperature-dependent swelling behavior of vapor-deposited smart polymer thin films is shown to depend on cross-linking and deposited film thickness. Smart polymers find application in sensor and actuator setups and are mostly fabricated on delicate substrates with complex nanostructures that need to be conformally coated. As initiated chemical vapor deposition (iCVD) meets these specific requirements, the present work concentrates on temperature-dependent swelling behavior of iCVD poly(N-isopropylacrylamide) thin films. The transition between swollen and shrunken state and the corresponding lower critical solution temperature (LCST) was investigated by spectroscopic ellipsometry in water. The films' density in the dry state evaluated from X-ray reflectivity could be successfully correlated to the position of the LCST in water and was found to vary between 1.1 and 1.3 g/cm3 in the thickness range 30-330 nm. This work emphasizes the importance of insights in both the deposition process and mechanisms during swelling of smart polymeric structures.

Scanning Electron Microscopy Analysis of the Anterior Capsulotomy Edge: A Comparative Study between Femtosecond Laser-Assisted Capsulotomy and Manual Capsulorhexis.

PURPOSE: To compare the capsule edges ultrastructure obtained by two femtosecond laser-assisted cataract surgery (FLACS) platforms and manual continuous curvilinear capsulorhexis (CCC) using scanning electron microscopy (SEM). SETTING: Eye Clinic, University of Trieste, Italy. DESIGN: Experimental comparative study. METHODS: 150 anterior capsules were collected and divided into three groups as follows: Group 1 (50 capsules) obtained with manual CCC, Groups 2 and 3 (each with 50 capsules) obtained with the Catalys Laser and the LenSx Laser, respectively. All samples were imaged by means of SEM and regularity of the cut surface, and thickness of the capsule edge were evaluated and compared. RESULTS: All femtosecond laser (FSL) capsules were perfectly circular, whereas some alteration of the circular shape was observed in the manual ones. Group 1 showed a smooth and regular capsule edge without any surface irregularity, conversely Groups 2 and 3 showed postage-stamp perforations on the capsule edge. The cut surface irregularity value in Group 2 was 1.4 ± 0.63, while it was 0.7 ± 0.49 in Group 3 (p < 0.05). Group 1 had a significantly lower thickness of the capsule edge than the FSL groups (p < 0.05). No statistically significant difference in the capsule edge thickness between the FSL groups was found (p=0.244). CONCLUSIONS: Despite the presence of slight cut surface irregularities, both FSL capsulotomies showed a better geometry and circularity than the manual ones. Capsulotomy specimens obtained using both FSL capsulotomies showed laser-induced alterations of the capsule edge when compared with smooth and regular edges obtained using manual CCC.

Growth Regimes of Poly(perfluorodecyl acrylate) Thin Films by Initiated Chemical Vapor Deposition.

Control over thin film growth (e.g., crystallographic orientation and morphology) is of high technological interest as it affects several physicochemical material properties, such as chemical affinity, mechanical stability, and surface morphology. The effect of process parameters on the molecular organization of perfluorinated polymers deposited via initiated chemical vapor deposition (iCVD) has been previously reported. We showed that the tendency of poly(1H,1H,2H,2H-perfluorodecyl acrylate) (pPFDA) to organize in an ordered lamellar structure is a function of the filament and substrate temperatures adopted during the iCVD process. In this contribution, a more thorough investigation of the effect of such parameters is presented, using synchrotron radiation grazing incidence and specular X-ray diffraction (GIXD and XRD) and atomic force microscopy (AFM). The parameters influencing the amorphization, mosaicity, and preferential orientation are addressed. Different growth regimes were witnessed, characterized by a different surface structuring and by the presence of particular crystallographic textures. The combination of morphological and crystallographic analyses allowed the identification of pPFDA growth possibilities between island or columnar growth.

Characterization of nano-porosity in molecular layer deposited films.

Molecular layer deposition (MLD) delivers (ultra-) thin organic and hybrid materials, with atomic-level thickness control. However, such layers are often reported to be unstable under ambient conditions, due to the interaction of water and oxygen with the hybrid structure, consequently limiting their applications. In this contribution, we investigate the impact of porosity in MLD layers on their degradation. Alucone layers were deposited by means of trimethylaluminium and ethylene glycol, adopting both temporal and spatial MLD and characterized by means of FT-IR spectroscopy, spectroscopic ellipsometry, and ellipsometric porosimetry. The highest growth per cycle (GPC) achieved by spatial MLD resulted in alucone layers with very low stability in ambient air, leading to their conversion to AlOx. Alucones deposited by means of temporal MLD, instead, showed a lower GPC and a higher ambient stability. Ellipsometric porosimetry showed the presence of open nano-porosity in pristine alucone layers. Pores with a diameter in the range of 0.42-2 nm were probed, with a relative content between 1.5% and 5%, respectively, which are attributed to the temporal and spatial MLD layers. We concluded that a correlation exists between the process GPC, the open-porosity relative content, and the degradation of alucone layers.

Quality of images with toric intraocular lenses.

PURPOSE: To objectively evaluate the image quality obtained with toric intraocular lenses (IOLs) when misaligned from the intended axis. SETTING: University Eye Clinic and the Department of Industrial and Information Engineering, University of Trieste, Trieste, Italy. DESIGN: Experimental study. METHODS: An experimental optoelectronic test bench was created. It consisted of a high-resolution monitor to project target images and an artificial eye. The system simulates the optical and geometric characteristics of the human eye with an implanted toric IOL. A 3.00 diopters corneal astigmatism was simulated. Images reproduced by the optical system were captured according to different IOL axis positions. The quality of each image was analyzed using the visual information fidelity (VIF) criterion. The VIF reduction was calculated at each IOL rotational step. RESULTS: A 5-degree IOL axis rotation from the intended position determined a decay in the image quality of 7.03%. Ten degrees of IOL rotation caused an 11.09% decay of relative VIF value. For a 30-degree rotation, the VIF decay value was 45.85%. Finally, the image decay with no toric correction was 56.70%. CONCLUSIONS: The more the objective quality of the image decays progressively, the further the axis of the IOL is rotated from its intended position. The reduction in image quality obtained after 30 degrees of toric IOL rotation was less than 50% and after 45 degrees, the image quality was the same as that of no toric correction.

Different Response Kinetics to Temperature and Water Vapor of Acrylamide Polymers Obtained by Initiated Chemical Vapor Deposition.

Thermoresponsive polymers undergo a reversible phase transition at their lower critical solution temperature (LCST) from a hydrated hydrophilic state at temperatures below the LCST to a collapsed hydrophobic state at higher temperatures. This results in a strong response to temperature when in aqueous environment. This study shows that hydrogel thin films synthesized by initiated chemical vapor deposition show fast and strong response to temperature also in water vapor environment. Thin films of cross-linked poly(N-isopropylacrylamide), p(NIPAAm), were found to have a sharp change in thickness by 200% in water vapor at temperatures above and below the LCST. Additionally, the stimuli-responsive poly(N,N-diethylacrylamide) was investigated and compared to results found for p(NIPAAm). Analysis of the swelling kinetics performed with in situ spectroscopic ellipsometry with variable stage temperature shows differences for swelling and deswelling processes, and a hysteresis in the thickness profile was found as a function of temperature and of temperature change rate.

Solution-based electrical doping of semiconducting polymer films over a limited depth.

Solution-based electrical doping protocols may allow more versatility in the design of organic electronic devices; yet, controlling the diffusion of dopants in organic semiconductors and their stability has proven challenging. Here we present a solution-based approach for electrical p-doping of films of donor conjugated organic semiconductors and their blends with acceptors over a limited depth with a decay constant of 10-20 nm by post-process immersion into a polyoxometalate solution (phosphomolybdic acid, PMA) in nitromethane. PMA-doped films show increased electrical conductivity and work function, reduced solubility in the processing solvent, and improved photo-oxidative stability in air. This approach is applicable to a variety of organic semiconductors used in photovoltaics and field-effect transistors. PMA doping over a limited depth of bulk heterojunction polymeric films, in which amine-containing polymers were mixed in the solution used for film formation, enables single-layer organic photovoltaic devices, processed at room temperature, with power conversion efficiencies up to 5.9 ± 0.2% and stable performance on shelf-lifetime studies at 60 °C for at least 280 h.

Dynamic Ellipsometric Porosimetry Investigation of Permeation Pathways in Moisture Barrier Layers on Polymers.

The quality assessment of moisture permeation barrier layers needs to include both water permeation pathways, namely through bulk nanoporosity and local macroscale defects. Ellipsometric porosimetry (EP) has been already demonstrated a valuable tool for the identification of nanoporosity in inorganic thin film barriers, but the intrinsic lack of sensitivity toward the detection of macroscale defects prevents the overall barrier characterization. In this contribution, dynamic EP measurements are reported and shown to be sensitive to the detection of macroscale defects in SiO2 layers on polyethylene naphthalate substrate. In detail, the infiltration of probe molecules, leading to changes in optical properties of the polymeric substrate, is followed in time and related to permeation through macroscale defects.