Visual Quality, Motility Behavior, and Retinal Changes Associated with Reading Tasks Performed on Electronic Devices

Background: The purpose of this study was to objectively evaluate visual discomfort using an eye tracker and aberrometer after a 21-min reading session on an iPad and an Ebook. Additionally, retinal changes were analyzed using optical coherence tomography (OCT). Methods: A total of 31 young subjects (24 ± 4 years) participated in this study. They read for 21 min on an Ebook and for another 21 min on an iPad under controlled lighting conditions while their eye movements were monitored using an eye tracker. Aberrometry and retinal OCT measurements were taken before and after each reading session. Parameters such as pupil diameter, fixations, saccades, blinks, total aberration, high-order aberration, low-order aberration, and central and peripheral retinal thickness in the nine early treatment diabetic retinopathy study (ETDRS) areas were measured for each reading situation. Statistical analysis was performed on the collected data. Results: No statistically significant differences (p > 0.05) between the two devices were observed in terms of the different types of eye movements or the changes in retinal thickness. However, the aberrometric analysis showed variations in post-reading situations depending on the device used. Conclusion: Reading speed and visual discomfort resulting from electronic device usage can be objectively assessed using an eye tracker and aberrometer. Additionally, changes found in central and peripheral retinal thickness between the two devices and the baseline measurements were not significant and remained relatively stable

Method to Calculate Melanopic Light Reaching the Retina Depending on the Optical Density of an Aging Crystalline Lens

Lighting studies that take into account the age of the inhabitants of an area and are related to circadian light are difficult to find. This study aims to simplify a method to approximately compute the circadian light reaching the retina based on photopic illuminance reaching the corneal plane and considering the optical density of an aging crystalline lens. As an example of this proposed method, calculations were performed with both the D65 and A standard illuminants, showing how the spectral power distribution is modified by the optical density of the crystalline lens, mainly at short wavelengths. Due to these selective wavelength absorptions of the aged lens, a significant variation in the level of daylight equivalent melanopic illuminance (EDI) is present in the retina. With levels of 200 lux at the corneal plane, these variations ranged from 204 EDI lux to 178 EDI lux for the D65 standard illuminant, and from 99 EDI lux to 101 EDI lux for the A standard illuminant for observers aged 10 and 90, respectively. In this work, we aimed to simplify the greatest possible level of calculation of melanopic light, while describing simple protocols that are easy to translate into practice. Our results will allow researchers to carry out optimized lighting designs from both the photometric and circadian perspectives considering the optical density of an aging lens

Optical and motor changes associated with lighting and near vision tasks in electronic devices

Purpose: To assess optical and motor changes associated with near vision reading under different controlled lighting conditions performed with two different types of electronic screens. Methods: Twenty-four healthy subjects with a mean age of 22.9±2.3 years (18-33) participated in this study. An iPad and an e-ink reader were chosen to present calibrated text, and each task lasted 5 minutes evaluating both ambient illuminance level and luminance of the screens. Results:Eye-tracker data revealed a higher number of saccadic eye movements under minimum luminance than under maximum luminance. The results showed statistically significant differences between the iPad (p=0.016) and the e-ink reader (p=0.002). The length of saccades was also higher for the minimum luminance level for both devices: 6.2±2.8 mm and 8.2±4.2 mm (e-ink max vs min), 6.8±2.9 mm and 7.6±3.6 mm (iPad max vs min), and blinking rate increased significantly for lower lighting conditions. Conclusions: Performing reading tasks on electronic devices is highly influenced by both the configuration of the screens and the ambient lighting, meanwhile, low differences in visual quality that are transient in healthy young people, were found

Lighting-Induced Changes in Central and Peripheral Retinal Thickness and Shape after Short-Term Reading Tasks in Electronic Devices

Background: To assess retinal and optical changes associated with near vision reading for different lighting conditions in electronic screens. Methods: Twenty-four young healthy subjects participated in the study; an iPad and an Ebook were chosen as stimuli for 5 min of reading task with different lighting conditions. Central and peripheral retinal thicknesses in the macular ETDRS areas by optical coherence tomography were analyzed. Results: Significant differences were found between basal retinal thickness and retinal thickness after reading with iPad and high illumination, in the N6 (p = 0.021) and I6 (p = 0.049) areas, and low illumination (S3: p = 0.008, N3: p = 0.018, I3: p = 0.021, N6: p = 0.018 and I6: p = 0.020), being thinner after reading. The same trend was observed after reading with an Ebook and high lighting in the N3 (p = 0.037) and N6 (p = 0.028). For low lighting conditions, only retinal thinning was observed. After reading, retinal shape analysis revealed significant changes from computed basal eccentricity for high lighting conditions only. At the periphery, those differences in eccentricity values were statistically significant for both lighting conditions. Conclusions: Young people can recover visual quality after 5 min of reading tasks at different lighting levels on electronic devices, while peripheral retinal expansion remains altered, especially at low lighting levels

Hess Lancaster screen test with eye tracker: an objective method for the measurement of binocular gaze direction

Background: To objectively measure with an eye tracker both eye movement conjugacy and gaze direction in different positions when performing the Hess Lancaster Screen Test (HLST) in a sample of control subjects without binocular dysfunction and compare the results with those of the traditional subjective HLST performance. Methods: The sample was selected avoiding subjects who suffered from suppression of one of the two eyes, visual acuity less than 20/25 on the Snellen chart in each eye, strabismus, or any symptom of binocular dysfunction that could alter the results. While performing the HLST, the examiner wrote down each of the points on a template in a traditional way while the eye tracker (Tobii Pro Fusion, Tobii AB, Danderyd, Sweden), placed in front of the subject, took objective measurements of the position of both eyes at each point. Of the 29 subjects recruited in this study, 13 subjects between 18 and 27 years old underwent the complete optometric examination and the HLST wearing anaglyph glasses; meanwhile, 16 people were excluded because of binocular or accommodative dysfunctions or because they didn’t give reliable eye-tracking results. Additionally, a specific program called Etracker Parse Video (University of Zaragoza, Zaragoza, Spain) was developed to analyse the prismatic deviation between both eyes at each evaluated point. Results: Similar horizontal prismatic deviations of visual axes were obtained in the different gaze positions with the Maddox rod, the manually annotated HLST, and the eye-tracker measurement. Variations were found in the magnitude of the deviation between methods but not in the direction. On the other hand, vertical deviations were more difficult for the examiner to detect and quantify, especially those with small magnitudes; more exact values were obtained when measuring objectively with the eye tracker. Conclusion: The HLST is very useful and allows the amount of heterophoria or heterotropia to be recorded in the patient’s medical record in all the main gaze positions. This test is complementary; by itself, it is not diagnostic and does not replace a complete examination of binocular vision. The eye tracker is an objective method with which we can evaluate the HLST in patients with no binocular problems, obtaining more accurate results than when it is performed in the traditional manner

Eye-tracker study of the developmental eye movement test in young people without binocular dysfunctions

Background: The purpose of this study was to evaluate ocular motility in normal young adults when performing the Developmental Eye Movement (DEM) test using an infrared eye-tracker in a sample of young subjects without visual dysfunctions. Methods: An optometric evaluation was carried out on 52 participants with a mean age of 21.00 ± 3.22 years to verify they did not have any binocular dysfunction, by completing a computerized version of the DEM test while their eye movements were recorded with an eye-tracker. A custom-written software was developed to analyse some specific parameters of ocular motility while performing each subtest (Test A, Test B and Test C) of the complete DEM test. Results: The mean duration of the fixations was shorter in Test C (243.56 ± 46.18 s) than in Test A (493.52 ± 171.41 s) and Test B (484.20 ± 156.59 s). The mean adjusted horizontal (AdjHT: 35.24 ± 6.68 s) and vertical (VT: 33.58 ± 5.56 s) times were at the 45th and at the 40th percentile, respectively. In Test C, there was a high positive significant correlation between the saccadic speed (cc: 0.77; p < 0.001) and the saccadic length (cc: 0.74; p < 0.001) of both eyes. Conclusions: The eye-tracker is an objective method to evaluate the DEM test in subjects without binocular dysfunctions, measuring and quantifying ocular motility parameters that are impossible with the traditional subjective method. The eye movements of both eyes are conjugated in each subject, having saccades of the same length and speed

Choroidal and Retinal Thicknesses in Type 2 Diabetes Mellitus with Moderate Diabetic Retinopathy Measured by Swept Source OCT

Background: To study choroidal thickness (CT) in type 2 diabetes mellitus (DM2) patients with moderate diabetic retinopathy (DR) and to correlate with changes in retinal thickness (RT) with swept-source OCT (SS-OCT) compared to healthy subjects. Methods: Fifty-four DM2 patients with moderate DR without diabetic macular edema (DME) and 73 age-matched healthy subjects were evaluated using SS-OCT to measure changes in total RT and CT in the nine areas of the Early Treatment Diabetic Retinopathy Study (ETDRS) macular grid. Results: The mean age was 64.06 ± 11.98 years and 60.79 ± 8.62 years in the diabetic and control groups, respectively. Total RT showed statistically significant differences in the temporal inner area, with higher values in the DM2 group (p = 0.010). CT did not show differences between the groups. There was a significant negative correlation between RT and age in all of the outer ETDRS areas and a positive significant correlation in the central area for the DM2 group. There was also a negative significant correlation between CT and age in all of the ETDRS areas except for the inferior inner area. In the DM2 group, a negative correlation was observed between RT and CT in the central area (p = 0.039) and in both horizontal parafoveal areas (temporal inner, p = 0.028; nasal inner, p= 0.003). Conclusion: DM2 patients with moderate DR have no changes with regard to CT. Both CT and RT decreased with age in DM2, showing a negative correlation between these factors in the central and horizontal parafoveal areas of the ETDRS grid

Spectral attenuation of brain and retina tissues in the near-infrared range measured using a fiber-based supercontinuum device

A novel setup for the efficient constant optical measurements of biological tissues in the near infrared is presented. The system combines the use of a fiber-based supercontinuum source with a simple optics fiber collimator. This configuration allows a wide spectral range of measurement and, at the same time, can efficiently filter the straightforward transmitted light while avoiding scattered light. As a performance example, the optical characterization of rat brain and retina tissues are shown. The attenuation coefficient for both tissues in the near infrared region is also obtained. This technique could be applied in clinical research as a noninvasive method with several potential practical applications

Development of lactoferrin-loaded liposomes for the management of dry eye disease and ocular inflammation

Dry eye disease (DED) is a high prevalent multifactorial disease characterized by a lack of homeostasis of the tear film which causes ocular surface inflammation, soreness, and visual disturbance. Conventional ophthalmic treatments present limitations such as low bioavailability and side effects. Lactoferrin (LF) constitutes a promising therapeutic tool, but its poor aqueous stability and high nasolacrimal duct drainage hinder its potential efficacy. In this study, we incorporate lactoferrin into hyaluronic acid coated liposomes by the lipid film method, followed by high pressure homogenization. Pharmacokinetic and pharmacodynamic profiles were evaluated in vitro and ex vivo. Cytotoxicity and ocular tolerance were assayed both in vitro and in vivo using New Zealand rabbits, as well as dry eye and anti-inflammatory treatments. LF loaded liposomes showed an average size of 90 nm, monomodal population, positive surface charge and a high molecular weight protein encapsulation of 53%. Biopharmaceutical behaviour was enhanced by the nanocarrier, and any cytotoxic effect was studied in human corneal epithelial cells. Developed liposomes revealed the ability to reverse dry eye symptoms and possess anti-inflammatory efficacy, without inducing ocular irritation. Hence, lactoferrin loaded liposomes could offer an innovative nanotechnological tool as suitable approach in the treatment of DED.FCT -Fundação para a Ciência e a Tecnologia(2017SGR1477)info:eu-repo/semantics/publishedVersio

Clinical and Laboratory Development of Echinocandin Resistance in Candida glabrata: Molecular Characterization

The pathogenic yeast Candida glabrata has become a public health issue due to the increasing number of echinocandin resistant clinical strains reported. In this study, acquisition and development of resistance to this antifungal class were studied in serial C. glabrata isolates from five patients admitted in two Spanish hospitals with a resistant profile against echinocandins associated with different mutations in hot-spot 1 of FKS2 gene. For two of these patients susceptible FKS wild-type isolates obtained prior to resistant ones were also investigated. Isolates were genotyped using multilocus sequence typing and microsatellite length polymorphism techniques, which yielded comparable results. Susceptible and resistant isolates from the same patient had the same genotype, being sequence type (ST) 3 the most prevalent among them. Isolates with different FKS mutations but the same ST were present in the same patient. MSH2 gene alterations were also studied to investigate their correlation with antifungal resistance acquisition but no association was found with antifungal resistance nor with specific genotypes. In vitro exposure to increasing concentrations of micafungin to susceptible isolates developed colonies carrying FKS mutations in agar plates containing a minimum concentration of 0.06 mg/L of micafungin after less than 48 h of exposure. We investigated the correlation between development of resistance and genotype in a set of susceptible strains after being in vitro exposed to micafungin and anidulafungin but no correlation was found. Mutant prevention concentration values and spontaneous growth frequencies after selection with both echinocandins were statistically similar, although FKS mutant colonies were more abundant after micafungin exposure (p < 0.001). Mutation S663P and F659 deletion were the most common ones found after selection with both echinocandins.This work was supported by the Fondo de Investigación Sanitaria (Grant FI14CIII/00025 to OR-M and research projects PI13/02145 and PI16CIII/00035 to AA-I), and also supported by the Plan Nacional de I+D+i 2013–2016 and Instituto de Salud Carlos III, Subdirección General de Redes y Centros de Investigación Cooperativa, Ministerio de Ciencia, Innovación y Universidades, Spanish Network for Research in Infectious Diseases (REIPI RD16CIII/0004/0003) – co-financed by the European Development Regional Fund “A way to achieve Europe,” Operative Program Intelligent Growth 2014–2020.S