Introduction and Validation of Low-Cost Ocular Biometry in Healthy and Cataractous Eyes Using a Thermally Tunable Swept-Source Laser.

PURPOSE: To introduce and validate a novel substantially lower-priced and rapid swept-source investigational optical biometer in healthy and cataractous eyes, using a thermally tuned laser diode used extensively in cell phones and data communication as an alternative swept source. DESIGN: Prospective accuracy, validity, and reliability analysis. METHODS: A total of 60 eyes of 59 subjects (29 eyes of 29 healthy subjects and 31 eyes of 30 cataract patients) were enrolled in a prospective comparative study at the Vienna General Hospital between August 2021 and April 2023. Averaged intraocular distances were acquired in 2.5 seconds from datasets consisting of 5000 consecutive A-scans at a single position by a low-cost swept-source optical biometry (SSOB) system. Instrument repeatability was assessed via standard deviations (SDs) and coefficients of variation (CoVs) of parameters such as axial length (AL), anterior chamber depth (ACD), lens thickness (LT), and central corneal thickness (CCT). Healthy subjects and cataract patients were subsequently measured on the same day with the SSOB and a referential partial coherence interferometry (PCI) biometer (IOLMaster 500) to establish AL inter-device correlation (r) for instrument calibration. AL and ACD as shared parameters between both biometers were evaluated for their limits of agreements (LoA) using Bland-Altman analysis. RESULTS: Repeated measurements of AL, ACD, LT, and CCT revealed SDs of 18 µm, 12 µm, 12 µm, and 10 µm, respectively. All parameters except for CCT had a COV <1%. Except for 1 eye with white cataract, 59 eyes of 59 study participants with various degrees and types of cataract could be measured with both devices. The AL inter-device correlation was excellent (r > 0.99). The 95% LoAs between both biometers were -0.14 to 0.13 mm for AL and -0.28 to 0.25 mm for ACD. CONCLUSIONS: Optical biometry using a thermally tunable VCSEL swept-source light source has the potential to provide clinically relevant biometric parameters at an unprecedented 100-fold lower price point than currently used state-of-the-art optical biometers, paving the way for compact devices in remote care settings.

Clinical outcomes after implantation of a novel binocular complementary extended depth of focus intraocular lens compared to bilateral low near-add multifocal intraocular lenses.

INTRODUCTION: Aim of this study was to assess the clinical outcomes of two diffractive intraocular lenses (IOL): a novel binocular complementary IOL compared to a conventional low near-add multifocal IOL (MIOL). METHODS: Patients scheduled for cataract surgery were randomly allocated into two groups receiving either binocular complementary optical systems (ARTIS SYMBIOSE Mid and Plus, Cristalens, France) or low near-add MIOL (AT LARA, Carl Zeiss Meditec AG, Germany). Patients had visual acuity (VA) assessment at distance, intermediate, and near as well as evaluation of contrast sensitivity, halometry and reading performance. RESULTS: In total, 56 eyes of 28 patients were enrolled. At 6 months, there were no statistically significant differences in visual acuity between the ARTIS SYMBIOSE and the AT LARA. Contrast sensitivity at 1.5 cycles per degree under photopic conditions without glare was 1.54 logCS with the ARTIS SYMBIOSE and 1.43 logCS with the AT LARA (p=0.046), under mesopic conditions with glare at 1.5 and 3 cycles per degree 1.31 logCS and 1.28 logCS with the ARTIS SYMBIOSE, respectively, compared to 0.58 logCS and 0.51 logCS with the AT LARA (p=0.002; p=0.006). Halos and reading performance between both groups were similar. CONCLUSION: There were no significant differences between both groups in visual acuity at different distances, reading ability or halometry. The contrast sensitivity at low spatial frequencies was better in the ARTIS SYMBIOSE group under photopic conditions with and without glare as well as mesopic conditions with glare.

Occurrence of Corneal Staining after Cataract Surgery with and without Chitosan-N-Acetylcysteine Eye Drops.

INTRODUCTION: The objective of this study was to evaluate the prevalence of ocular surface damage assessed by corneal staining scores right after cataract surgery and whether it can be prevented using chitosan-N-acetylcysteine (C-NAC) eye drops. METHODS: We included patients scheduled for routine cataract surgery. Each patient was randomly assigned to one of three groups. Patients in group 1 underwent routine cataract surgery with no additional eye drops. In group 2, patients received C-NAC eye drops after cataract surgery, and in group 3, C-NAC was applied both before and after surgery. Both groups continued the treatment once daily for 4 days. Ocular surface alteration was assessed using the National Eye Institute (NEI) score, and the visual analog scale (VAS) was used to evaluate subjective complaints. RESULTS: Thirty-six patients were included in the final analyses. One hour after cataract surgery, a statistically significant increase in corneal fluorescein staining was observed in all groups, which decreased again after 1 week. There was no significant difference between the groups 1 h after cataract surgery, though a tendency toward lower NEI scores was observed during this time point in group 3. DISCUSSION: Cataract surgery induced ocular surface staining and subjective complaints after 1 h. However, the increase in VAS score was small and probably not clinically relevant. The application of perioperative C-NAC eye drops did reduce the rate of corneal staining after cataract surgery in a clinically relevant manner.

Comparison of corneal aberrations from anterior segment swept source OCT versus Placido-topography combined spectral domain OCT in cataract patients.

BACKGROUND: To comprehensively evaluate the agreement of component corneal aberrations from the newly updated wavefront analysis software of a swept-source optical coherence tomographer (SS-OCT) and a referential Placido-topography combined OCT device in elderly cataract patients. METHODS: Retrospective study including 103 eyes from 103 elderly patients scheduled for cataract surgery that were measured on the same day with a SS-OCT (Heidelberg Engineering, Germany) device and a Placido-topography combined OCT device (CSO, Italy). Anterior, total, and posterior corneal wavefront aberrations were evaluated for their mean differences and limits of agreement (LoA) via Bland-Altman plots. Vector analysis was additionally employed to compare corneal astigmatism measurements in dioptric vector space. RESULTS: Mean differences of all corneal aberrometric parameters did not exceed 0.05 µm. Total corneal aberrations were not significantly different from 0 except for vertical coma (- 0.04 µm; P = 0.003), spherical aberration (- 0.01 µm, P < 0.001), and root mean square (RMS) higher-order aberration (HOA) (0.03 µm, P = 0.04). The 95% LoA for total corneal aberration parameters between both devices were - 0.46 to 0.42 µm for horizontal astigmatism, - 0.37 to 0.41 µm for oblique astigmatism, - 0.19 to 0.17 µm for oblique trefoil, - 0.33 to 0.25 µm for vertical coma, - 0.20 to 0.22 µm for horizontal coma, - 0.22 to 0.20 µm for horizontal trefoil, - 0.11 to 0.08 µm for spherical aberration, and - 0.22 to 0.28 µm for RMS HOA. Vector analysis revealed no statistically significant mean differences for anterior, total, and posterior corneal astigmatism in dioptric vector space. CONCLUSION: In eyes undergoing cataract surgery with a regular elderly cornea, corneal wavefront analysis from the SS-OCT device showed functional equivalency to the reference device. Nevertheless, clinically relevant higher order aberration parameters should be interpreted with caution for surgical decision-making.

Surface Photovoltage Study of Metal Halide Perovskites Deposited Directly on Crystalline Silicon.

Perovskite (PVK) films deposited directly on n-type crystalline Si substrates were investigated by two operating modes of the surface photovoltage (SPV) method: (i) the metal-insulator-semiconductor (MIS) mode and (ii) the Kelvin probe force microscopy (KPFM). By scanning from 900 to 600 nm in the MIS mode, we consecutively studied the relatively fast processes of carrier generation, transport, and recombination first in Si, then on both sides of the PVK/Si interface, and finally in the PVK layer and its surface. The PVK optical absorption edge was observed in the range of 1.61-1.65 eV in good agreement with the band gap of 1.63 eV found from photoluminescence spectra. Both SPV methods evidenced an upward energy band bending at the PVK/n-Si interface generating positive SPV. Drift-diffusion modeling allowed us to analyze the shape of the wavelength dependence of the SPV. It was also observed that the intense illumination in the KPFM measurements induces slow SPV transients which were explained by the creation and migration of negative ions and their trapping at the PVK surface. Finally, aging effects were studied by measuring again SPV spectra after one-year storage in air, and an increase in the concentration of shallow defect states at the PVK/n-Si interface was found.

Structure-Function Analysis of MP-3 Microperimetry versus Octopus Perimetry in Central Glaucomatous Visual Field Defects.

INTRODUCTION: The aim of this study was to compare the structure-function relationship with microperimetry and Octopus perimetry in primary open-angle glaucoma (POAG) patients with central visual field (VF) defects. METHODS: Forty eyes of 24 patients with POAG were enrolled. Circumpapillary retinal nerve fiber layer (cpRNFL) analysis measured by spectral-domain optical coherence tomography (SD-OCT) of the superotemporal, temporal, and inferotemporal optic-nerve head sectors were related to corresponding microperimetric and Octopus VF clusters using the G2 grid-pattern with dynamic strategy, respectively. The structure-function relationships of both devices were assessed via a segmented regression, as well as linear regression across overall SD-OCT cpRNFL values and outside normative (<1%) SD-OCT cpRNFL values. RESULTS: Linear and segmented regression fits were similar with both devices. Across overall cpRNFL sectorial values, structure-function relations for the superotemporal, temporal, and inferotemporal sectors were R2 = 0.176 (p = <0.001), R2 = 0.008 (p = 0.069), and R2 = 0.294 (p = <0.001) for microperimetry and R2 = 0.189 (p = <0.001), R2 = 0.020 (p = 0.002), and R2 = 0.326 (p = <0.001) for Octopus perimetry. For corresponding values outside normative limits (<1%), the relationships were R2 = 0.113 (p = <0.001), R2 = 0.001 (p = 0.836), and R2 = 0.420 (p = <0.001) for microperimetry and R2 = 0.192 (p = <0.001), R2 = 0.002, (p = 0.336), and R2 = 0.366 (p = <0.001) for Octopus perimetry. DISCUSSION/CONCLUSION: Structure-function analysis was similar for both devices. Fundus-tracking should be further evaluated in a longitudinal setting in patients affected by glaucoma.

Clinical implementation of a 3D4K-exoscope (Orbeye) in microneurosurgery.

Exoscopic surgery promises alleviation of physical strain, improved intraoperative visualization and facilitation of the clinical workflow. In this prospective observational study, we investigate the clinical usability of a novel 3D4K-exoscope in routine neurosurgical interventions. Questionnaires on the use of the exoscope were carried out. Exemplary cases were additionally video-documented. All participating neurosurgeons (n = 10) received initial device training. Changing to a conventional microscope was possible at all times. A linear mixed model was used to analyse the impact of time on the switchover rate. For further analysis, we dichotomized the surgeons in a frequent (n = 1) and an infrequent (n = 9) user group. A one-sample Wilcoxon signed rank test was used to evaluate, if the number of surgeries differed between the two groups. Thirty-nine operations were included. No intraoperative complications occurred. In 69.2% of the procedures, the surgeon switched to the conventional microscope. While during the first half of the study the conversion rate was 90%, it decreased to 52.6% in the second half (p = 0.003). The number of interventions between the frequent and the infrequent user group differed significantly (p = 0.007). Main reasons for switching to ocular-based surgery were impaired hand-eye coordination and poor depth perception. The exoscope investigated in this study can be easily integrated in established neurosurgical workflows. Surgical ergonomics improved compared to standard microsurgical setups. Excellent image quality and precise control of the camera added to overall user satisfaction. For experienced surgeons, the incentive to switch from ocular-based to exoscopic surgery greatly varies.

Digital ocular swept source optical coherence aberrometry.

Ocular aberrometry is an essential technique in vision science and ophthalmology. We demonstrate how a phase-sensitive single mode fiber-based swept source optical coherence tomography (SS-OCT) setup can be employed for quantitative ocular aberrometry with digital adaptive optics (DAO). The system records the volumetric point spread function at the retina in a de-scanning geometry using a guide star pencil beam. Succeeding test-retest repeatability assessment with defocus and astigmatism analysis on a model eye within ± 3 D dynamic range, the feasibility of technique is demonstrated in-vivo at a B-scan rate of >1 kHz in comparison with a commercially available aberrometer.

Surgical Management of Failed Revascularization in Moyamoya Vasculopathy.

Objectives: Moyamoya vasculopathy (MMV) is a rare stenoocclusive cerebrovascular disease associated with increased risk of ischemic and hemorrhagic stroke, which can be treated using surgical revascularization techniques. Despite well-established neurosurgical procedures performed in experienced centers, bypass failure associated with neurological symptoms can occur. The current study therefore aims at characterizing the cases of bypass failure and repeat revascularization at a single center. Methods: A single-center retrospective analysis of all patients treated with revascularization surgery for MMV between January 2007 and December 2019 was performed. Angiographic data, cerebral blood flow analysis [H2O PET or single-photon emission CT (SPECT)], MRI, and clinical/operative data including follow-up assessments were reviewed. Results: We identified 308 MMV patients with 405 surgically treated hemispheres. Of the 405 hemispheres treated, 15 patients (3.7%) underwent repeat revascularization (median age 38, time to repeat revascularization in 60% of patients was within 1 year of first surgery). The most common cause of repeat revascularization was a symptomatic bypass occlusion (80%). New ischemic lesions were found in 13% of patients prior to repeat revascularization. Persistence of reduced or progressive worsening of cerebrovascular reserve capacity (CVRC) compared with preoperative status was observed in 85% of repeat revascularization cases. Intermediate-flow bypass using a radial artery graft was most commonly used for repeat revascularization (60%) followed by re-superficial temporal artery to middle cerebral artery (re-STA-MCA) bypass (26%). High-flow bypass using a saphenous vein graft and using an occipital artery to MCA bypass was each used once. Following repeat revascularization, no new ischemic events were recorded. Conclusion: Overall, repeat revascularization is needed only in a small percentage of the cases in MMV. A rescue surgery should be considered in those with neurological symptoms and decreased CVRC. Intermediate-flow bypass using a radial artery graft is a reliable technique for patients requiring repeat revascularization. Based on our institutional experience, we propose an algorithm for guiding the decision process in cases of bypass failure.

Anterior chamber depth variability between 2 hydrophobic acrylic 1-piece intraocular lenses: randomized trial.

PURPOSE: To analyze the difference in anterior chamber depth (ACD) after uneventful cataract surgery between 2 hydrophobic acrylic 1-piece intraocular lenses (IOLs) with different material properties. SETTING: Hanusch Hospital, Vienna, Austria. DESIGN: Single-center, bilateral randomized paired-eye controlled study. METHODS: Patients scheduled for bilateral cataract surgery were randomized to receive the Clareon IOL in 1 eye and the AcrySof IQ IOL (both Alcon Laboratories, Inc.) in the contralateral eye. Preoperatively, a slitlamp examination, optical biometry (IOLMaster 700, Carl Zeiss Meditec AG), refraction, and visual acuity measurements were performed. ACD was assessed 1 hour and 1 week postoperatively and with additional measurement of uncorrected (UDVA) and corrected distance visual acuity (CDVA) 6 months postoperatively. RESULTS: 80 eyes of 40 patients were analyzed in this study. ACD at the 6-month follow-up was 3.94 ± 0.30 mm for the Clareon IOL and 3.91 ± 0.32 mm for the AcrySof IQ IOL (P = .08). Statistically significant differences in the ACD shift between both IOLs were detected between 1 week and 6 months (P = .04) and 1 hour and 6 months (P = .04). There were no statistically significant differences between both IOLs in UDVA (P = .78), CDVA (P = .59), and spherical equivalent (SE, P = .39) at the 6-month visit. The mean absolute error between the measured and the aimed SE was not significant (P = .97). CONCLUSIONS: There was no clinically relevant difference in ACD between the Clareon IOL and the AcrySof IQ IOL in patients after uneventful cataract surgery. Both IOLs yielded good refraction and visual acuity outcomes.