Eye Surface Area Research Articles

Realistic microplastics harness bacterial presence and promote impairments in early zebrafish embryos: Behavioral, developmental, and transcriptomic approaches.

The plastisphere is a newly recognized ecosystem. However, its interaction with early life stages of aquatic vertebrates is a multifaceted issue that requires further research. This study investigated the involvement of bacteria in shaping realistic microplastics hazards in zebrafish Danio rerio embryos. Fish were exposed to bottle micro-fragments (FR) and textile micro-fibers (FI) of polyethylene terephthalate (5–15 μm), concomitant with Aeromonas salmonicida achromogenes challenge from 2h post-fertilization for 3 days. Egg chorion showed affinity for FR and FI, inducing earlier embryo hatching. However, this effect was masked by biofilm invasion. Fragments were more detrimental than fibers on developmental parameters, while bacterial presence compromised body length, eye, and yolk sac surface area. In a further finding, MPs alone increased locomotor activity in zebrafish larvae, without synergistic effect when combined with bacteria. Data showed that realistic MPs had no significant effects except for downregulated sod and cyp1a gene expression, whereas bacterial challenge inhibited larval potency for most of the evaluated mRNA levels (mpx (immune system), apoeb (lipid metabolism), nfkb and tfa (inflammation), cyp and sod (oxidative stress)). This study provides new insights into realistic microplastic effects under relevant conditions when combined with environmental pathogen within the first life stages of aquatic vertebrates.

Eye morphology and colour preferences in a semi-field test of the pine pest, Sirex noctilio (Hymenoptera: Siricidae)

The woodwasp, Sirex noctilio, is a global pest of pines. Although it is known to be attracted to light and possess sexually dimorphic body colouration, the visual ecology of S. noctilio is poorly understood. Photoreceptor sensitivity of the compound eyes in S. noctilio is not sexually dimorphic. These previous results suggest that colour tracking of one sex by the other might not be an important input for mate searching. This study aimed to expand our knowledge of the visual system of S. noctilio by means of i) morphological description of the compound eyes and ocelli; and ii) semi-field behavioural tests of the colour preference of newly emerged wasps. Eye and ocellus morphological features were investigated in 21 males and 21 females. Measurement of male and female median ocellus diameter, compound eye surface area, number of ommatidia and facet diameter varied from 0.22 to 0.40 mm, 0.589 to 2.277 mm2, 1820 to 4207 and 1.88 × 10–2 to 2.82 × 10–2 mm, respectively. In addition, all traits significantly correlated with body size. Male and female wasps emerged from infested host material in a flight cage with five traps, each reflecting a different colour. Analysis of trap captures did not identify any colour preference, but an effect of trap location was observed with traps in the north-eastern position capturing more woodwasps, suggesting that other factors, e.g., global landmarks or other non-colour visual cues might guide initial flight behaviour of S. noctilio.

Host-trailing satellite flight behaviour is associated with greater investment in peripheral visual sensory system in miltogrammine flies

Insect sensory systems are the subjects of different selective pressures that shape their morphology. In many species of the flesh fly subfamily Miltogramminae (Diptera: Sarcophagidae) that are kleptoparasitic on bees and wasps, females perch on objects close to the host nests and, once a returning host is detected, they follow it in flight at a fixed distance behind until reaching the nest. We hypothesized that such satellite (SAT) flight behaviour, which implies a finely coordinated trailing flight, is associated with an improved visual system, compared to species adopting other, non-satellite (NON-SAT) strategies. After looking at body size and common ancestry, we found that SAT species have a greater number of ommatidia and a greater eye surface area when compared to NON-SAT species. Ommatidium area is only affected by body size, suggesting that selection changes disproportionately (relative to body size variation) the number of ommatidia and as a consequence the eye area, instead of ommatidium size. SAT species also tend to have larger ocelli, but their role in host-finding was less clear. This suggests that SAT species may have a higher visual acuity by increasing ommatidia number, as well as better stability during flight and motion perception through larger ocelli. Interestingly, antennal length was significantly reduced in SAT species, and ommatidia number negatively correlated with antennal length. While this finding does not imply a selection pressure of improved antennal sensory system in species adopting NON-SAT strategies, it suggests an inverse resource (i.e. a single imaginal disc) allocation between eyes and antennae in this fly subfamily.

Pupil changes in persons aged 8 to 79 during text reading – an eye-tracking study

Summary The Eye Tribe eye-tracker was used to capture pupil sizes and fixation times of 40 people aged 8 to 79 years during text reading. The dependence of the number of readable lines on the participants’ age was determined. A function describing the dependence of the eye surface area on age was also derived. Visual perception of the maximum number of consecutive lines with decreasing text font size is best for people aged 30–40. For the studied age group, the pupil area decreased with age by approximately 300%. An approximately two-fold increase in average fixation times was recorded.

The eyes have it: dim-light activity is associated with the morphology of eyes but not antennae across insect orders

Abstract The perception of cues and signals in visual, olfactory and auditory modalities underpins all animal interactions and provides crucial fitness-related information. Sensory organ morphology is under strong selection to optimize detection of salient cues and signals in a given signalling environment, the most well-studied example being selection on eye design in different photic environments. Many dim-light active species have larger compound eyes relative to body size, but little is known about differences in non-visual sensory organ morphology between diurnal and dim-light active insects. Here, we compare the micromorphology of the compound eyes (visual receptors) and antennae (olfactory and mechanical receptors) in representative pairs of day active and dim-light active species spanning multiple taxonomic orders of insects. We find that dim-light activity is associated with larger compound eye ommatidia and larger overall eye surface area across taxonomic orders but find no evidence that morphological adaptations that enhance the sensitivity of the eye in dim-light active insects are accompanied by morphological traits of the antennae that may increase sensitivity to olfactory, chemical or physical stimuli. This suggests that the ecology and natural history of species is a stronger driver of sensory organ morphology than is selection for complementary investment between sensory modalities.

A simplified index to quantify the irritation/corrosion potential of chemicals – Part II: Eye

Eye irritation is a key human health endpoint assessed by in vitro and in vivo methods. One of the commonly used scoring methods to quantify the eye irritation potential of chemicals is the Modified Maximum Average Score (MMAS). It is dependent on the eye irritation effects (e.g. corneal opacity) originally proposed by Draize and then partially adopted by the OECD TG 405. These scores are not always fully reported in regulatory dossiers and lead to several drawbacks, 1) the difficulty to translate MMAS into a classification within the existing EU CLP/UN GHS criteria, 2) the absence of corrosion (serious eye damage), and 3) the dependency on input parameters which are usually not required under the OECD TGs (e.g. eye surface area). This study determined if classification can be driven by a maximum of two observed effects thereby simplifying the scoring calculation. The Simplified Irritation Index (SIIEYE), based only on corneal opacity and conjunctival redness, was developed using validated studies representing multiple chemical groups. A correlation was observed between the MMAS and the SIIEYE allowing harmonisation of the classification for the existing data. This index proved to be useful in the development of in silico model.

Photogrammetric analysis of patients with facial palsy and its correlation with the Sunnybrook facial grading system

No consensus has been reached on an ideal method to objectively measure facial palsy, especially for patients with synkinesis.1,2 We previously reported the use of landmarks to photogrammetrically assess ocular synkinesis3 and smile excursion in healthy individuals.4 These include: the angle between the commissure, contralateral commissure, and ipsilateral endocanthion (CCE); eye surface area (ESA); and midline to commissure distance (MCD). The aim of this study was to compare affected and non-affected hemi-faces of patients with facial palsy using these landmarks and assess its correlation with Sunnybrook facial grading system scores.

The relationship between microhabitat use, allometry and functional variation in the eyes of Hawaiian Megalagrion damselflies

Summary The evolution of visual systems is guided by visual requirements imposed by the environment, the size of the animal's eyes, and physical limitations imposed by the resolution‐sensitivity trade‐off. Given a particular eye surface area, resolution and sensitivity cannot be simultaneously maximized: gains in resolution, the ability of the eye to detect detail, will come at the cost of sensitivity, the ability to capture photons, and vice versa, without an increase to eye size. How this constraint interacts with ecology and whether it allows the fine‐tuning of the visual system to smaller scale habitat heterogeneity remains an understudied question in visual ecology. Here, we use closely‐related species of damselflies in the Hawaiian genus Megalagrion which differ in ecology to test whether variation in the resolution‐sensitivity trade‐off is the evolutionary result of scaling or differences in microhabitat use. We use regression analyses and phylogenetic comparative methods to examine the effects of size and microhabitat use on traits related to light sensitivity and visual resolution. We find that eye size is tightly associated with body size in these damselflies, but other visual morphology traits related to light sensitivity and resolution are associated with microhabitat type. Furthermore, size and morphology relationships vary across microhabitats, and performance related to resolution tends to be more conserved than to variation in light sensitivity. Additionally, smaller species in visually challenging microhabitats have more regionalized eyes than species with larger eyes in open, well‐lit areas. Thus, regionalization of the eye allows a decoupling of size and morphology/performance so that even small insect species can exploit visually challenging habitats. These results suggest that variation in visual performance results from changes in eye geometry as well as size. These morphological changes are likely adaptive to differences in microhabitat, indicating that variation in microhabitat use, even at small scales, can play an important role in the evolution of visual systems.

How do eye size and facet lens size vary by age and sex inAcheta domesticus?

Abstract. Vision is essential to interactions with the environment and survival of many animals. House crickets, Acheta domesticus, are nocturnal insects with compound apposition eyes, and thus may have a specialized visual system selected for low-light vision. Here, an analysis of regional variation in facet diameter around the eye of a cricket was conducted. Eye surface area was estimated and facet diameter was spot-sampled across the eyes of 13 adults and 13 juveniles. Juveniles had smaller facets than adults, and there was significant variation among eye regions in facet size. Specifically, larger facets were found in the posterior eye region. Overall, facets were large given the size of this animal's eye, which is consistent with what one might expect from a nocturnal insect under selection for high sensitivity. Furthermore, juveniles had proportionally larger facets than adults, which may indicate that the insects maximize the sensitivity of their ommatidia early in development, prior to increasing ...

Orbit Orientation and Eye Morphometrics in Giraffes (Giraffa camelopardalis)

Giraffe are thought to have excellent vision. We measured eye size, orbit orientation and retina surface area in 27 giraffes of both sexes ranging in age from neonates to mature adults (>10 yrs), to assess how it changes with growth, whether their eye anatomy correlates with their apparently excellent vision and lifestyle, and we have compared our findings with those for other large mammals to assess whether giraffe eye anatomy is unique. We found that giraffe eye volume increases from 33 cm3 at birth to approximately 65 cm3 in adults. The focal (axial) length increases from c. 40 to 48 mm in adults and retina surface area from c. 3000 mm2 at birth to 4320 mm2 in adults. The orbital axis angle at birth is c. 73° and the horizontal visual field mainly monocular and panoramic. With age the axis angle becomes more acute to c. 50° in adults and the visual field more binocular, changes that occur concurrently with increasing neck length. These results show that the giraffe eye and retinal surface area are larger than in all other ungulates, and their visual fields more binocular, attributes which are consistent with the idea that they have excellent vision.

Orbit orientation and eye morphometrics in giraffes (Giraffa camelopardalis)

Giraffe are thought to have excellent vision. We measured eye size, orbit orientation and retina surface area in 27 giraffes of both sexes ranging in age from neonates to mature adults (>10 yrs), to assess how it changes with growth, whether their eye anatomy correlates with their apparently excellent vision and lifestyle, and we have compared our findings with those for other large mammals to assess whether giraffe eye anatomy is unique. We found that giraffe eye volume increases from 33 cm3 at birth to approximately 65 cm3 in adults. The focal (axial) length increases from c. 40 to 48 mm in adults and retina surface area from c. 3000 mm2 at birth to 4320 mm2 in adults. The orbital axis angle at birth is c. 73° and the horizontal visual field mainly monocular and panoramic. With age the axis angle becomes more acute to c. 50° in adults and the visual field more binocular, changes that occur concurrently with increasing neck length. These results show that the giraffe eye and retinal surface area are larger than in all other ungulates, and their visual fields more binocular, attributes which are consistent with the idea that they have excellent vision.

Validation of a new photogrammetric technique to monitor the treatment effect of Botulinum toxin in synkinesis

To validate a new photogrammetric technique for quantifying eye surface area and using this to quantify the degree of improvement in symmetry in patients with oral-ocular synkinesis following Botulinum toxin injection. Feasibility study and retrospective outcomes analysis Ten patients' photographs were chosen from a photographic database. Their eye surface areas were measured independently by two raters using a graphics tablet. One rater repeated the procedure after 15 days. Bland-Altman plots were computed, ascertaining inter-rater and intra-rater variability. The eye surface areas of 19 patients were then derived from photographs taken before and after Botulinum toxin injections. Paired t-tests were used to analyse the significance of the difference in pre- and post-treatment symmetry. Ninety per cent of eye surface areas derived from the two raters were within a coefficient of variation of 0.1 (95% CI: 0.05-0.15). Similarly, 90% of eye surface areas derived from one rater had a coefficient of variation of 0.08 (95% CI: 0.04-0.12). Botulinum toxin significantly reduced synkinesis resulting from lip puckering, Mona Lisa smiling and Hollywood smiling (P<0.05). We have proposed a clinically valid tool for quantifying the effects of Botulinum toxin treatment for oral-ocular synkinesis. We recommend this method be used to monitor the response of such patients when receiving Botulinum toxin treatment.

Variations in Eye Volume, Surface Area, and Shape with Refractive Error in Young Children by Magnetic Resonance Imaging Analysis

To determine variations in eye volume, surface area, and shape with refractive error in young children using a three-dimensional magnetic resonance imaging (MRI) model. A subset of Singaporean Chinese boys enrolled in the population-based Strabismus, Amblyopia, and Refractive Error in Singapore (STARS) study underwent MRI using a 3-Tesla whole body scanner with a 32-channel head coil. Eye volume and surface area were measured. Eye shape was assessed qualitatively from the three-dimensional models and quantitatively by measurement of the longitudinal axial length (LAL), horizontal width, and vertical height along the cardinal axes. One hundred thirty-four eyes of 67 subjects (mean age, 77.9 ± 3.9 months) were analyzed. The mean spherical equivalent (SE) refraction was 0.65 ± 0.92 D (range, -2.31 to 4.13 D). More myopic SE was associated with larger surface area (-20.59 [-37.09 to -4.10] mm²/D; P = 0.01) but not volume. In age-height adjusted models, more myopic SE was associated with longer LAL (-1.94 [-2.47 to -1.41] mm/D; P < 0.001) and greater width (-1.12 [-1.26 to -0.99] mm/D; P < 0.001) but not height (0.64 [-2.55 to 3.82] mm/D; P = 0.70). In nonmyopic subjects, less hyperopic SE was associated with longer AL (-0.40 [-0.71 to -0.10] mm/D; P = 0.01), width (-0.59 [-0.84 to -0.34] mm/D; P < 0.001), and height (-0.40 [-0.64 to -0.17] mm/D; P = 0.001). In three-dimensional models, myopic eyes conformed to an axial elongation model with a prolate profile in the axial plane, whereas nonmyopic eyes showed global expansion. Eye surface area increases with myopia in young children. Eye shape is different in myopia, even in its early stages. Axial globe enlargement occurs in myopic eyes leading to a prolate shape, whereas nonmyopic eyes enlarge globally in length, width, and height.

Morphometry of eyes, antennae and wings in three species of Siagona (Coleoptera, Carabidae)

In carabid beetles, physiological and behavioural characteristics reflect specific habitat demands and there is a strong correlation between body form and habit in species with different life style. In this study, we compared the morphometry and compound eye characteristics of three species of the genus Siagona: Siagona jenissoni, Siagona dejeani and Siagona europaea. These carabids have a stenotopic lifestyle in Mediterranean clayey soils, inhabiting the ground fissure system formed during the dry season. All species have a Mediterranean distribution and are nocturnal olfactory hunters, and are strict ant predators. For morphometric measurements, we considered body length (mm), wing length (mm), antenna length (mm), head width (mm), trochanter length (mm), number of ommatidia, eye surface area (mm2), ommatidia density (number of ommatidia/mm2 of eye surface area), head height (mm), thorax height (mm) and abdomen height (mm). The data revealed intersexual and interspecific differences. The three species differ in relative length of the antennae, density and number of ommatidia and relative trochanter length. Significant differences occurred in wing sizes, which are well developed in Siagona europaea, the only species capable of flight. When eye size is compared with other ground beetles of various lifestyles, Siagona shows pronounced “microphthalmy” an adaptation to subterranean life in clayey crevices of tropical and subtropical climates with a marked dry season.

Eye Surface Area and Dosage Rates for Spray Vaccination

Spray application of Mycoplasma gallisepticum (MG) vaccines is a labor- and time-saving means of mass vaccination of layer chickens. Recent assessment of spray characteristics of nozzles commonly used to apply MG vaccine in layer chicken operations has shown that the amount of respirable droplets (< 5 microm) is negligible. Topical application of vaccine onto the eye surface has been suggested as a route of vaccination, but no estimates of vaccine load delivered via spray application were found in the literature. Estimates of eye surface area were developed using digital imaging; 24 layer pullets were used for analysis, and the mean eye surface area, corrected for corneal curvature, was found to be 0.609 cm2. This surface area was then used to estimate vaccine load for commercially available live MG vaccine sprayed through popular nozzles. Less than 3000 colony-forming units can be expected for direct deposition onto the surface of an eye.

Eye Surface Area and Dosage Rates for Spray Vaccination

Eye Surface Area and Dosage Rates for Spray Vaccination

Factors Regulating Eye Blink Rate in Young Infants

The purpose of this work was to investigate whether individual differences in eye surface area are related to the rate of spontaneous eye blinking (SB) in young infants. Rate of SB was also compared with the rate of gaze shifts. Forty-four 4-month-old infants were observed under controlled conditions for 4 to 6 min. SB, eye surface area, gaze shifts, and various background variables were measured. Individual differences in the rate of SB and in eye surface area were wide. Neither the eye surface area nor the rate of gaze shifting was related to the rate of SB in young infants. However, when SB do occur, they are more likely to coincide with a shift in gaze than immediately precede or follow a shift in gaze. Eye surface area does not explain individual differences in the rate of SB in infancy. This and other recent work suggests that central factors may play a more prominent role in the mechanisms of SB early in human development than previously reported and that the mechanisms regulating the rate of SB seem to be developmentally continuous with those of adults. To the extent that the rate and timing of SB reflects developing neurological systems, SB may be useful clinically.

3-Dimensional modelling of chick embryo eye development and growth using high resolution magnetic resonance imaging

Magnetic resonance imaging (MRI) is a powerful tool for generating 3-dimensional structural and functional image data. MRI has already proven valuable in creating atlases of mouse and quail development. Here, we have exploited high resolution MRI to determine the parameters necessary to acquire images of the chick embryo eye. Using a 9.4 Tesla (400 MHz) high field ultra-shielded and refrigerated magnet (Bruker), MRI was carried out on paraformaldehyde-fixed chick embryos or heads at E4, E6, E8, and E10. Image data were processed using established and custom packages (MRICro, ImageJ, ParaVision, Bruker and mri3dX). Voxel dimensions ranged from 62.5 μm to 117.2 μm. We subsequently used the images obtained from the MRI data in order to make precise measurements of chick embryo eye surface area, volume and axial length from E4 to E10. MRI was validated for accurate sizing of ocular tissue features by direct comparison with previously published literature. Furthermore, we demonstrate the utility of high resolution MRI for making accurate measurements of morphological changes due to experimental manipulation of chick eye development, thereby facilitating a better understanding of the effects on chick embryo eye development and growth of such manipulations. Chondroitin sulphate or heparin were microinjected into the vitreous cavity of the right eyes of each of 3 embryos at E5. At E10, embryos were fixed and various eye parameters (volume, surface area, axial length and equatorial diameter) were determined using MRI and normalised with respect to the un-injected left eyes. Statistically significant alterations in eye volume (p < 0.05; increases with chondroitin sulphate and decreases with heparin) and changes in vitreous homogeneity were observed in embryos following microinjection of glycosaminoglycans. Furthermore, in the heparin-injected eyes, significant disturbances at the vitreo-retinal boundary were observed as well as retinal folding and detachment confirming histological observations. These data reveal the utility and superiority of MRI for producing images enabling quantification of experimentally induced changes in eye volume and structure. The results indicate that MRI is an important tool that could become a routine approach for rapid and sensitive phenotypic analysis of normal chick ocular development and morphology as well as potentially the effects of surgical or genetic manipulations of chick embryo eyes in live embryos in ovo.

A Method for Measuring the Surface Features of the Firefly (Coleoptera: Lampyridae) Compound Eye

An inexpensive miniature stage goniometer compatible with a conventional optical microscope was developed to study the size and distribution of ommatidia facets across the compound eye of fireflies (Coleoptera: Lampyridae). The goniometer device was used to take sequential overlapping images of the hemispherical surface along longitudinal great-circle arcs of each eye of Photinus carolinus firefly and Photuris sp. males and females. Images covering the entire eye required 7 great circle scans at increments of 26° rotation. Using the multiple images, we minimized distortions associated with imaging a spherical surface in 2 dimensions and measured surface features with an error of &amp;lt;1.5%. A polar plot provided a consistent display format to relate facet area with location on the surface of the eye. We tested the functionality of the goniometer on a small number of male and female fireflies. It enabled us to make accurate measurements of surface features and address whether there is sexual dimorphism in firefly eyes. Within our limited sample, our results indicated that male eyes were larger than female eyes. In both firefly species the difference between the two sexes in the eye surface area was found statistically significant (P&amp;lt; 0.0001, unpaired t-tests). Male and female eyes also exhibited regional variation in facet area. We hypothesize that the sexual dimorphism and regional variation of firefly eye reflect functional and behavioral capabilities.

Morphometry and eye morphology in three species of Carabus (Coleoptera: Carabidae) in relation to habitat demands

Morphological features of three common European olfactory hunting carabid beetles, Carabus coriaceus mediterraneus Born, 1906, Carabus lefebvrei Dejean, 1826 and Carabus preslii neumeyeri Schaum, 1856, were compared. According to eye measurements, the three species are nocturnal and/or twilight hunters. They differ, however, in relative length of the antennae, relative surface area of the compound eyes, density of ommatidia and relative head width. These differences can be correlated with the species-specific habitat demands (light intensity, open land or shaded places). In particular, the greater lateral eye protrusion in C. lefebvrei corresponds to its tree-climbing habits, while the larger relative eye surface area and ommatidia density in C. coriaceus correspond to its choice of open habitats. Sono state investigate le caratteristiche morfometriche e dei componenti degli occhi di tre specie di coleotteri carabidi predatori olfattivi, Carabus coriaceus mediterraneus Born (1906), C. lefebvrei Dejean (1826) e C. presliineumeyeri Schaum (1856). Le differenze dei parametri considerati, nelle tre specie in esame, sono riconducibili con le diverse caratteristiche dei diversi habitat sfruttati. In particolare, sono state riscontrate differenze nella protrusione laterale degli occhi, che è maggiore in C. lefebvrei, probabilmente perchéè l'unica delle tre specie che si arrampica sugli alberi, e nell'area delle cornee e numero di ommatidi, maggiore in C. coriaceus, specie che predilige habitat aperti.