SciCombinator

Discover the most talked about and latest scientific content & concepts.

Concept: Human eye

262

We tested whether eye color influences perception of trustworthiness. Facial photographs of 40 female and 40 male students were rated for perceived trustworthiness. Eye color had a significant effect, the brown-eyed faces being perceived as more trustworthy than the blue-eyed ones. Geometric morphometrics, however, revealed significant correlations between eye color and face shape. Thus, face shape likewise had a significant effect on perceived trustworthiness but only for male faces, the effect for female faces not being significant. To determine whether perception of trustworthiness was being influenced primarily by eye color or by face shape, we recolored the eyes on the same male facial photos and repeated the test procedure. Eye color now had no effect on perceived trustworthiness. We concluded that although the brown-eyed faces were perceived as more trustworthy than the blue-eyed ones, it was not brown eye color per se that caused the stronger perception of trustworthiness but rather the facial features associated with brown eyes.

Concepts: Eye, Photoreceptor cell, Color, Qualia, Rod cell, Cone cell, Human eye, Eye color

163

Multispectral imaging is a powerful tool that extends the capabilities of the human eye. However, multispectral imaging systems generally are expensive and bulky, and multiple exposures are needed. Here, we report the demonstration of a compact multispectral imaging system that uses vertical silicon nanowires to realize a filter array. Multiple filter functions covering visible to near-infrared (NIR) wavelengths are simultaneously defined in a single lithography step using a single material (silicon). Nanowires are then etched and embedded into polydimethylsiloxane (PDMS), thereby realizing a device with eight filter functions. By attaching it to a monochrome silicon image sensor, we successfully realize an all-silicon multispectral imaging system. We demonstrate visible and NIR imaging. We show that the latter is highly sensitive to vegetation and furthermore enables imaging through objects opaque to the eye.

Concepts: Eye, Demonstration, Image sensor, Imaging, Visible spectrum, Human eye, Eye color, Multi-spectral image

7

Human eyes serve two key functions in face-to-face social interactions: they provide cues about a person’s emotional state and attentional focus (gaze direction). Both functions critically rely on the morphologically unique human sclera and have been shown to operate even in the absence of conscious awareness in adults. However, it is not known whether the ability to respond to social cues from scleral information without conscious awareness exists early in human ontogeny and can therefore be considered a foundational feature of human social functioning. In the current study, we used event-related brain potentials (ERPs) to show that 7-mo-old infants discriminate between fearful and nonfearful eyes (experiment 1) and between direct and averted gaze (experiment 2), even when presented below the perceptual threshold. These effects were specific to the human sclera and not seen in response to polarity-inverted eyes. Our results suggest that early in ontogeny the human brain detects social cues from scleral information even in the absence of conscious awareness. The current findings support the view that the human eye with its prominent sclera serves critical communicative functions during human social interactions.

Concepts: Brain, Human brain, Cerebral cortex, Eye, Mind, Consciousness, Event-related potential, Human eye

3

Vascularized composite allotransplantation of the eye is an appealing, novel method for reconstruction of the nonfunctioning eye. The authors' group has established the first orthotopic model for eye transplantation in the rat. With advancements in immunomodulation strategies together with new therapies in neuroregeneration, parallel development of human surgical protocols is vital for ensuring momentum toward eye transplantation in actual patients.

Concepts: Eye, Organ transplant, Ophthalmology, Rat, Human eye, Eye color, 2004 films

3

To quantify changes in ocular dimensions associated with age, refractive error, and accommodative response, in vivo, in 30- to 50-year-old human subjects.

Concepts: Refraction, In vivo, Eye, Ophthalmology, Myopia, Human eye, Eye color

1

Cells are minute-typically too small to be seen by the human eye. Even so, the cellular world encompasses a range of scales, from roughly a tenth of a nanometer (10(-10) m) to a millimeter (10(-3) m) or larger, spanning seven orders of magnitude or more. Because they are so far from our experience, it is difficult for us to envision such scales. To help our imagination grasp such dimensions, I propose the adoption of a ‘perceptive scale’ that can facilitate a more direct experience of cellular sizes. From this, as I argue below, will stem a new perception also of biological shape, cellular space and dynamic processes.

Concepts: Biology, Organism, Species, Cell biology, Orders of magnitude, Eye, Perception, Human eye

1

The human eye has typically more optical aberrations than conventional artificial optical systems. While the lower order modes (defocus and astigmatism) are well studied, our purpose is to explore the influence of genes versus the environment on the higher order aberrations of the optical components of the eye.

Concepts: Biology, Optics, Natural environment, Eye, Lens, Geometrical optics, Human eye, Eye color

0

The brown planthopper ATP-binding cassette (ABC) proteins White (W), Scarlet (St) and Brown (Bw) belong to the ABC transporter superfamily and are responsible for the transportation of guanine and tryptophan precursors of eye pigments. In the present study, the brown planthopper White (NlW), S t(NlSt) and Bw (NlBw) genes were cloned, and subsequent phylogenetic analysis showed that these genes are clustered with their respective homologues, with a genetic relationship observed between NlW and its Bemisia tabaci homologue having the highest similarity. Sequence alignments showed that these three proteins have a highly conserved Walker A domain, an ABC “signature sequence” and a Walker B domain. QRT-PCR demonstrated that W, St and Bw are highly expressed in the head of long-winged males and are highly expressed in both egg and male. Adult eye colour was altered after the downregulation of NlW, NlSt and NlBw in the 1st to 3rd instar nymph. The eye colours of emerged adults became white, dark and red after injection of dsNlW, dsNlSt and dsNlBw, respectively. The eye pigment content assay revealed that xanthommatin and pteridine were significantly decreased after the injection of dsRNAs, and the range of variation was inversely correlated with nymph age. The present study provides a theoretical basis for understanding the function of ABC transporters at the molecular and biochemical levels.

Concepts: Gene, Eye, Color, Melanin, Pigment, Human eye, Eye color, ATP-binding cassette transporter

0

Our goal was to quantify and characterize how the collagen fiber crimp waviness of the lamina cribrosa (LC) and peripapillary sclera (PPS) changes with intraocular pressure (IOP). Thirteen sheep (ovine) eyes were immersion and perfusion fixed while maintaining IOP at 0, 10, 15, 20, or 50mmHg. Coronal optic nerve head (ONH) sections (30 µm) were imaged with polarized light microscopy (PLM) and analyzed for collagen fiber orientation and waviness (SD of fiber orientation). In the LC, the waviness of every LC beam was measured. In the PPS, at least 900 collagen bundles were measured per eye. Using the waviness at 50mmHg IOP, we defined tissue-specific thresholds to determine the fraction of loaded or recruited fibers. We found that fiber waviness decreased with IOP (P<0.001). At every IOP, the waviness of the collagen fibers, and the fraction of fibers recruited in the LC were smaller or equal than those of the PPS (P<0.001). At 15mmHg IOP, both LC and PPS had ¾ recruited fibers and ¼ left in reserve. The decreased waviness with IOP and associated fiber recruitment is experimental evidence of fiber-based nonlinear biomechanical behavior of the ONH. At all IOPs the PPS had an equal or larger fraction of fibers recruited than the LC. That both LC and PPS had the same fraction of recruited and reserve fibers at normal IOP suggests that this may be an optimal fraction of recruitment for healthy eyes. Whether this extends to human eyes remains unknown. STATEMENT OF SIGNIFICANCE [109/120]: Collagen fibers exhibit a natural waviness or crimp that largely determine the nonlinear biomechanics of soft tissue. Experimental measurements of crimp morphology in the sheep eye, and how it changes with intraocular pressure (IOP), however, are exceedingly sparse. We quantified how posterior eye crimp changes with increasing IOP. We found that the lamina cribrosa and peripapillary sclera have fundamentally different crimp, and with increasing IOP, have different proportions of fibers that straighten, or get recruited, versus remaining wavy, or in reserve. Interestingly, at physiologic IOP of 15 mmHg, both tissues had about ¾ fibers recruited and ¼ fibers in reserve, indicating there may be an optimal fraction of fibers.

Concepts: Retina, Eye, Cornea, Fiber, Polarization, Human eye, Blind spot, Optic disc

0

With recent changes in the recommended annual limit on eye lens exposures to ionizing radiation, there is considerable interest in predictive computational dosimetry models of the human eye and its various ocular structures including the crystalline lens, ciliary body, cornea, retina, optic nerve, and central retinal artery. Computational eye models to date have been constructed as stylized models, high-resolution voxel models, and polygon mesh models. Their common feature, however, is that they are typically constructed of nominal size and of a roughly spherical shape associated with the emmetropic eye. In this study, we present a geometric eye model that is both scalable (allowing for changes in eye size) and deformable (allowing for changes in eye shape), and that is suitable for use in radiation transport studies of ocular exposures and radiation treatments of eye disease. The model allows continuous and variable changes in eye size (axial lengths from 20 to 26 mm) and eye shape (diopters from -12 to +6). As an explanatory example of its use, five models (emmetropic eyes of small, average, and large size, as well as average size eyes of -12D and +6D) were constructed and subjected to normally incident beams of monoenergetic electrons and photons, with resultant energy-dependent dose coefficients presented for both anterior and posterior eye structures. Electron dose coefficients were found to vary with changes to both eye size and shape for the posterior eye structures, while their values for the eye crystalline lens were found to be sensitive to changes in only eye size. No dependence upon eye size or eye shape was found for photon dose coefficients at energies below 2 MeV. Future applications of the model can include more extensive tabulations of dose coefficients to all ocular structures (not only the lens) as a function of eye size and shape, as well as the assessment of x-ray therapies for ocular disease for patients with non-emmetropic eyes.

Concepts: Electron, Ionizing radiation, Retina, Eye, Visual perception, Cornea, Lens, Human eye