Tear-Based Vibrational Spectroscopy Applied to Amyotrophic Lateral Sclerosis.

Biofluid analysis by optical spectroscopy techniques is attracting considerable interest due to its potential to revolutionize diagnostics and precision medicine, particularly for neurodegenerative diseases. However, the lack of effective biomarkers combined with the unaccomplished identification of convenient biofluids has drastically hampered optical advancements in clinical diagnosis and monitoring of neurodegenerative disorders. Here, we show that vibrational spectroscopy applied to human tears opens a new route, offering a non-invasive, label-free identification of a devastating disease such as amyotrophic lateral sclerosis (ALS). Our proposed approach has been validated using two widespread techniques, namely, Fourier transform infrared (FTIR) and Raman microspectroscopies. In conjunction with multivariate analysis, this vibrational approach made it possible to discriminate between tears from ALS patients and healthy controls (HCs) with high specificity (∼97% and ∼100% for FTIR and Raman spectroscopy, respectively) and sensitivity (∼88% and ∼100% for FTIR and Raman spectroscopy, respectively). Additionally, the investigation of tears allowed us to disclose ALS spectroscopic markers related to protein and lipid alterations, as well as to a reduction of the phenylalanine level, in comparison with HCs. Our findings show that vibrational spectroscopy is a new potential ALS diagnostic approach and indicate that tears are a reliable and non-invasive source of ALS biomarkers.

Care System Versus Transmitted Light Wavefront Pattern of Contact Lenses.

OBJECTIVES: This article compares the optical performance of soft contact lenses (CLs) treated with multipurpose or hydrogen peroxide care systems. METHODS: The investigated care systems were (1) 3% hydrogen peroxide solution Oxysept (Abbot Medical Optics, Abbott Park, IL) and (2) multipurpose solution Regard (Vita Research, Ariccia, Italy). Three types of silicone hydrogel CLs were studied (comfilcon A, lotrafilcon B, and balafilcon A), unworn and exposed for 30 times to the solutions, which were replaced every 8 hr. The optical performance of the CLs was evaluated through the on-eye transmitted light wavefront patterns by considering new CLs as references. The surface morphology of the CLs was investigated by scanning electron microscopy. RESULTS: Statistically significant modifications in the range 0.1 to 0.3 µm of Zernicke coefficients and modifications of the root mean square of the wavefront aberration function were found for CLs treated with multipurpose solution, in agreement with the observed modifications of the surface morphology. Statistically significant changes were also found after exposure to the hydrogen peroxide solution, but the variation of the Zernicke coefficients was found lower than 0.1 µm, thus being negligible in CL optical performances. CONCLUSIONS: In addition to disinfection ability and ocular surface reactions, CL care systems are different in solution-related CL optical performance. Multipurpose solutions may affect the CL surface morphology with significant modifications of the transmitted light wavefront pattern.

The development of an augmented reality device for the autonomous management of the electric bed and the electric wheelchair for patients with amyotrophic lateral sclerosis: a pilot study.

PURPOSE: The main aim of this Human Centred Design project was to develop the Environment COntrol in Amyotrophic Lateral Sclerosis (ECO-ALS) System, a new device which could improve ALS patient's autonomy in controlling the environment. Moreover, we verified the feasibility and usability of this technology in ALS patients in advanced stages of the disease. MATERIAL AND METHODS: Twelve ALS patients in advanced disease stage were recruited, two patients for the development phase and ten patients and their caregivers for the two weeks' trial phase. We evaluated the impact of the ECOALS system by administering the Psychosocial Impact of Assistive Devices Scale (PIADS), the Individual Prioritised Problem Assessment (IPPA), the McGill Quality of Life Questionnaire (MQOL) and the Caregiver Burden Inventory (CBI). RESULTS: In the trial phase, patients were very satisfied for having recovered their autonomy in the management of the EAB, that enabled patients to reduce calls to their caregivers to change their bed position. The IPPA questionnaire showed a significant improvement in patients' participation and management of the system. Moreover, the PIADS questionnaire showed that patients perceived a progress in competence, adaptability and areas of self-esteem, confirming a positive psychosocial impact of the patients' assistance device. CONCLUSION: The project has collected some useful information for technological system development to face the need for autonomy ALS patients. Patients were satisfied with the tested aids and were interested in the future developments. Further studies are needed to improve the system and overcome some technical problems that occurred during the project.IMPLICATIONS FOR REHABILIATIONThe ECO-ALS system seems to improve the patients' perceived autonomy.The ECO-ALS system seems to improve the patients' perceived progress in competence, adaptability and areas of self-esteem, confirming a positive psychosocial impact of the assistance device.The ECO-ALS system seems to improve the patients' perceived quality of life.Patients were satisfied with the tested aids and were interested in the future developments.

Ocular Involvement Occurs Frequently at All Stages of Amyotrophic Lateral Sclerosis: Preliminary Experience in a Large Italian Cohort.

BACKGROUND AND PURPOSE: The study aimed to obtain optometric findings of amyotrophic lateral sclerosis (ALS) patients in different stages of the disease, and to determine the relation between ocular data and ALS-related features; that is, functional and cognitive impairment and staging. METHODS: The optometric protocol included tests of the ocular motility [broad-H test and Northeastern State University College of Optometry (NSUCO) test], near point of convergence (NPC), error refraction, best-corrected visual acuity, and binocular visual alignment, and an ocular symptoms questionnaire. The functional measures included the Amyotrophic Lateral Sclerosis Functional Rating Scale-revised (ALSFRS-r) and Milano-Torino staging (MiToS), and cognitive impairment was assessed using the Edinburgh Cognitive and Behavioural ALS Screen (ECAS). Demographic and clinical features were also collected, including whether the patients used an eye-tracking communication device (ETCD). RESULTS: Two-hundred consecutive ALS patients (median age of 64 years, 118 males and 82 females) in different stages of disease were recruited. Nearly 70% of patients reported at least one ocular symptom, and the use of an ETCD was found to be significantly related to the presence of most symptoms. Moreover, the severely symptomatic group was characterized by significantly lower ALSFRS-r total and subscale scores, and higher MiToS. Abnormal NPC values were significantly related to lower ALSFRS-r total and bulbar-subscale scores. Patients with acceptable NSUCO test values exhibited significantly higher ECAS scores. CONCLUSIONS: The presence of ocular alteration in patients in different stages of ALS supports the idea that this is a multisystem disorder and emphasizes the importance of optometric evaluations in multidisciplinary assessments to address ocular impairment early in the disease process.

Association of Clinically Evident Eye Movement Abnormalities With Motor and Cognitive Features in Patients With Motor Neuron Disorders.

BACKGROUND AND OBJECTIVES: Although oculomotor abnormalities (OMAs) are not usually considered prominent features of amyotrophic lateral sclerosis (ALS), they may represent potential clinical markers of neurodegeneration, especially when investigated together with cognitive and behavioral alterations. The aim of our study was to identify patterns of clinically evident OMAs in patients with ALS and to correlate such findings with cognitive-behavioral data. METHODS: Three consecutive inpatient cohorts of Italian patients with ALS and controls were retrospectively evaluated to assess the frequency of OMAs and cognitive-behavioral alterations. The ALS population was divided into a discovery cohort and a replication cohort. Controls included a cohort of cognitively impaired individuals and patients with Alzheimer disease (AD). Participants underwent bedside eye movement evaluation to determine the presence and pattern of OMAs. Cognitive assessment was performed with a standard neuropsychological battery (discovery ALS cohort and AD cohort) and the Italian Edinburgh Cognitive and Behavioural ALS Screen (ECAS) (replication ALS cohort). RESULTS: We recruited 864 individuals with ALS (635 discovery, 229 replication), 798 who were cognitively unimpaired and 171 with AD. OMAs were detected in 10.5% of our ALS cohort vs 1.6% of cognitively unimpaired controls (p = 1.2 × 10-14) and 11.4% of patients with AD (p = NS). The most frequent deficits were smooth pursuit and saccadic abnormalities. OMA frequency was higher in patients with bulbar onset, prominent upper motor neuron signs, and advanced disease stages. Cognitive dysfunction was significantly more frequent in patients with OMAs in both ALS cohorts (p = 1.1 × 10-25). Furthermore, OMAs significantly correlated with the severity of cognitive impairment and with pathologic scores at the ECAS ALS-specific domains. Last, OMAs could be observed in 35.0% of cognitively impaired patients with ALS vs 11.4% of patients with AD (p = 6.4 × 10-7), suggesting a possible involvement of frontal oculomotor areas in ALS. CONCLUSION: Patients with ALS showed a range of clinically evident OMAs, and these alterations were significantly correlated with cognitive, but not behavioral, changes. OMAs may be a marker of neurodegeneration, and bedside assessment represents a rapid, highly specific tool for detecting cognitive impairment in ALS.

Slit-lamp based assessment of peripheral versus central regions of the human corneal endothelium.

PURPOSE: To compare the central and peripheral (< 2 mm from the limbus) endothelial regions of the human cornea of young contact lens (CL) neophytes, in terms of endothelial cell density (ECD), polymorphism through cell hexagonality (HEX), and polymegethism through the coefficient of variation of cell areas (CoV). MATERIALS AND METHODS: In vivo, central, temporal, and nasal ECDs, HEXs, and CoVs were determined for thirty healthy right eyes (age: 22-30 years) using a Takagi 700 G L LED slit-lamp biomicroscope equipped with the centre-dot EndoKer© for the analysis of endothelium images. RESULTS: The mean central ECD (2586 ±â€¯233 mm-2) was lower than peripheral ECDs (nasal 2733 ±â€¯225 mm-2, temporal 2674 ±â€¯260 mm-2) (p = 0.03 and p = 0.02, respectively). The mean central HEX (53.0 ±â€¯4.6%) was lower than peripheral HEXs (nasal 57.2 ±â€¯4.3%, temporal 57.1 ±â€¯4.5%) (both p < 0.005), while the mean central CoV (28.2 ±â€¯2.5%) was higher than peripheral CoVs (nasal 25.8 ±â€¯2.2%, temporal 26.1 ±â€¯2.2%) (both p ≤ 0.001). CONCLUSIONS: In young healthy non-CL wearers, the peripheral corneal endothelium displays a higher ECD and significantly better cell regularity (higher HEX and lower CoV) compared to the central cornea. A clinical evaluation of the corneal endothelium requires, therefore, a full characterization of the different areas.

Improvement or Worsening of Human Contrast Sensitivity Due to Blue Light Attenuation at 450 nm.

PURPOSE: The work was aimed at comparing contrast sensitivity performance in an indoor environment with two filters, which differ only in the presence of a band at 450±20 nm in the transmittance spectrum. PATIENTS AND METHODS: Thirty-nine subjects participated. The filters were the Standard (ST) and Professional (PRO) Drive lenses (Hoya, Japan), the latter showing the attenuation band at 450 nm. Photopic contrast sensitivity (CS) was measured at different spatial frequencies from 1.5 to 18 cpd through Functional Acuity Contrast Test with both lenses (LogCSST and LogCSPRO, respectively). The areas under the curves of LogCSST and LogCSPRO as a function of the spatial frequency were also considered. RESULTS: In the range of the measured values of LogCSST for the thirty-nine participants, at each spatial frequency and also for the areas, the difference Δ = LogCSPRO - LogCSST was found to decrease and change sign from positive to negative as a function of LogCSST, thus allowing to deduce a threshold (LogCSthreshold) for LogCSST corresponding to Δ=0. Significant CS worsening was found with the PRO compared to the ST lens for the subjects showing LogCSST > LogCSthreshold. Vice versa, CS improvement was found when LogCSST < LogCSthreshold. CONCLUSION: In the choice of a blue-filtering lens, practitioners should take into consideration that the attenuation of light in the range 420-470 nm is expected to produce a CS worsening in subjects showing a relatively high initial CS (higher than a threshold CS). For these subjects, the general reduction of transmitted light intensity prevails on possible advantages. On the contrary, subjects showing a relatively low initial CS are expected to show a CS improvement because the attenuation of light in the range 420-470 nm is expected to reduce intraocular scattering and to mimic the effect as an optical filter of the human macular pigment, advantages which prevail on the reduction of the transmitted light intensity.

The effects of two longpass filters on visual performance.

PURPOSE: This study compared visual performance and optical properties of three filters. METHOD: Two groups of twenty adults were recruited: wearers of progressive addition lenses (PAL, 46-73 years) and wearers of single vision lenses (SVL, 26-55 years). Three spectacle filters (Hoya, Japan) were compared: clear control, Standard Drive (STD), and Professional Drive (PRO) lenses. Optical transmittance was measured by a Jasco V-650 spectrophotometer. Best corrected visual acuity (BCVA) was measured in photopic (BCVAphotopic) and mesopic (BCVAmesopic) conditions and under glare (BCVAglare). Photopic contrast sensitivity (CS) was also measured. RESULTS: The three longpass filters show cutoff at 426±2nm (STD/PRO) and 405±2nm (clear lens). BCVAglare improved with Drive filters compared to the clear one (p<0.05) from 0.03 to -0.02 (STD) and to -0.01 (PRO) for PAL and from -0.08 to -0.12 (STD and PRO) for SVL. For PAL, BCVAmesopic improved from 0.15 to 0.12 (STD, p<0.05) and 0.13 (PRO), while no substantial difference was observed for SVL. CS showed some improvements with Drive lenses at some angular frequencies between 6 and 18 cycles/deg, mainly for the PAL group. No BCVAphotopic differences were found. After testing all filters, each for two weeks, 79% (PAL) and 60% (SVL) of participants preferred Drive lenses. CONCLUSIONS: Drive lenses are found to maintain or improve some visual functions compared to the clear lens. The improvement of mesopic visual acuity, visual acuity under glare, and contrast sensitivity is mainly attributed to the reduction of intraocular light scattering as a consequence of the total light attenuation in the spectral range below the cutoff.

Criticality of the measurement of corneal thickness in specular reflection by digital biomicroscope.

PURPOSE: The aim was to evaluate the effects on corneal thickness (t) measurement, of asymmetry of the CCD position for a digital biomicroscope in specular reflection. METHODS: t was deduced from the distance between reflexes from anterior and posterior corneal surfaces using a biomicroscope (Takagi SM70 N), with the illuminator either, (a) farther from sensor side (150 eyes) or, (b) closer to it (134 eyes). The distance between reflexes was also measured on a glass slide and a reference lens, with nominal thicknesses of 1580 and 520 µm, respectively. Corneal thickness (tPACH) was also measured by pachymeter (Canon TX-20 P). RESULTS: When biomicroscope asymmetry was ignored, t for the glass slide was (a) 1760 and (b) 1404 µm. Correcting for the asymmetry provided corresponding values of 1588 and 1591 µm. For the lens, t was (a) 696 and (b) 543 µm, or 642 and 497 µm, when using the approximation of parallel surfaces (APS). Correcting for the asymmetry gave 565 and 552 µm (578 and 564 µm, with APS). Mean corneal t was (a) 560 and (b) 467 µm, (564 and 468 µm, with APS). Correcting for asymmetry gave (a) 506 and (b) 529 µm (508 and 530 µm, with APS). Mean tPACH was 552 µm. CONCLUSION: Biomicroscope asymmetry critically affects corneal thickness measurement in specular reflection. Induced errors can be accounted for and corrected, however. While the correction to the curvature radius is clinically relevant, it plays a minor role compared to asymmetry.

Variable-Size Bead Layer as Standard Reference for Endothelial Microscopes.

PURPOSE: For morphometric analysis of the cell mosaic of corneal endothelium, checking accuracy and precision of instrumentation is a key step. In this study, a standard reference sample is proposed, developed to reproduce the cornea with its shape and the endothelium with its intrinsic variability in the cell size. METHODS: A polystyrene bead layer (representing the endothelium) was deposited on a lens (representing the cornea). Bead diameters were 20, 25, and 30 µm (fractions in number 55%, 30%, and 15%, respectively). Bead density and hexagonality were simulated to obtain the expected true values and measured using a slit-lamp endothelial microscope applied to 1) a Takagi 700GL slit lamp at 40× magnification (recommended standard setup) and 2) a Takagi 2ZL slit lamp at 25× magnification. RESULTS: The simulation provided the expected bead density 2001 mm and hexagonality 47%. At 40×, density and hexagonality were measured to be 2009 mm (SD 93 mm) and 45% (SD 3%). At 25× on a different slit lamp, the comparison between measured and expected densities provided the factor 1.526 to resize the image and to use the current algorithms of the slit-lamp endothelial microscope for cell recognition. CONCLUSIONS: A variable-size polystyrene bead layer on a lens is proposed as a standard sample mimicking the real shape of the cornea and the variability of cell size and cell arrangement of corneal endothelium. The sample is suggested to evaluate accuracy and precision of cell density and hexagonality obtained by different endothelial microscopes, including a slit-lamp endothelial microscope applied to different slit lamps, also at different magnifications.

Morphometric Analyses by a New Slit-Lamp Endothelial Biomicroscope.

PURPOSE: A method called EndoKer was recently devised for the morphometric analysis of the cell mosaic of the corneal endothelium. Fully automatic cell recognition is performed on images acquired by a slit-lamp biomicroscope. The aim of this study was to evaluate the accuracy of the EndoKer results. METHODS: Analyses were performed on a polystyrene bead layer stratified on a contact lens and in vivo on 30 adults. Accuracy was evaluated by comparing the results of EndoKer with the true values obtained by manual counting of the cells in the same images. EndoKer results were also compared with those obtained with the Tomey EM3000 microscope. RESULTS: The accuracy of the results compared with the manual counting on the same images showed a difference of a few percent for the cell density and for hexagonality. This high accuracy derives from (1) the resolution of the slit-lamp images and (2) the improved cell recognition of the fully automatic method. A good agreement was also found between EndoKer and the Tomey EM3000 microscope results. CONCLUSIONS: Based on the investigated 30 cases, the slit-lamp biomicroscope may be a viable alternative to dedicated endothelial instruments, providing the additional advantages of a larger investigated area and the possibility to take images of different portions of the cornea. The calibration was performed during the development of the method by using polystyrene beads. The user is not required to perform this calibration. However, such a calibrated sample is suggested for those interested.

Wear effects on microscopic morphology and hyaluronan uptake in siloxane-hydrogel contact lenses.

The purpose of this study was a comparison between new and worn siloxane-hydrogel contact lenses in terms of microscopic structure, surface morphology, and loading of hyaluronan. The analyses were performed by scanning electron microscopy, with the support of the freeze-drying technique, and by fluorescence confocal microscopy. Along the depth profile of new lenses, a thin porous top layer was observed, which corresponds to the region of hyaluronan penetration inside well-defined channels. The time evolution was followed from one day to two weeks of daily wear, when a completely different scenario was found. Clear experimental evidence of a buggy surface was observed with several crests and regions of swelling, which could be filled by the hyaluronan solution. The modifications are attributed to the progressive relaxation of the structure of the polymeric network.

Mechanically triggered solute uptake in soft contact lenses.

Molecular arrangement plays a role in the diffusion of water and solutes across soft contact lenses. In particular, the uptake of solutes in hydrated contact lenses can occur as long as free water is available for diffusion. In this work, we investigated the effect of mechanical vibrations of low frequency (200 Hz) on the solute uptake. Hyaluronan, a polysaccharide of ophthalmic use, was taken as example of solute of interest. For a specific water-hydrated hydrogel material, differential scanning calorimetry experiments showed that a large fraction of the hydration water accounted for loosely-bound water, both before and after one week of daily-wear of the lenses. The size (of the order of magnitude of few hundreds of nanometers) of hyaluronan in aqueous solution was found to be less than the size of the pores of the lens observed by scanning electron microscopy. However, solute uptake in already-hydrated lenses was negligible by simple immersion, while a significant increase occurred under mechanical vibrations of 200 Hz, thus providing experimental evidence of mechanically triggered enhanced solute uptake, which is attributed to the release of interfacial loosely-bound water. Also other materials were taken into consideration. However, the effectiveness of mechanical vibrations for hyaluronan uptake is restricted to lenses containing interfacial loosely-bound water. Indeed, loosely-bound water is expected to be bound to the polymer with bonding energies of the order of magnitude of 10-100 J/g, which are compatible with the energy input supplied by the vibrations.

Hydrogen peroxide mechanosynthesis in siloxane-hydrogel contact lenses.

Drug-loaded contact lenses are emerging as the preferred treatment method for several ocular diseases, and efforts are being directed to promote extended and controlled delivery. One strategy is based on delivery induced by environmental triggers. One of these triggers can be hydrogen peroxide, since many platforms based on drug-loaded nanoparticles were demonstrated to be hydrogen-peroxide responsive. This is particularly interesting when hydrogen peroxide is the result of a specific pathophysiological condition. Otherwise, an alternative route to induce drug delivery is here proposed, namely the mechano-synthesis. The present work represents the proof-of-concept of the mechanosynthesis of hydrogen peroxide in siloxane-hydrogel contact lenses as a consequence of the cleavage of siloxane bonds at the interface between the polymer and water in aqueous phase. Their spongy morphology makes contact lenses promising systems for mechanical-to-chemical energy conversion, since the amount of hydrogen peroxide is expected to scale with the interfacial area between the polymer and water. The eyelid pressure during wear is sufficient to induce the hydrogen peroxide synthesis with concentrations which are biocompatible and suitable to trigger the drug release through hydrogen-peroxide-responsive platforms. For possible delivery on demand, the integration of piezoelectric polymers in the siloxane-hydrogel contact lenses could be designed, whose mechanical deformation could be induced by an applied wireless-controlled voltage.