Prenatal monocular enucleation induces a selective loss of low-spatial-frequency cortical responses to the remaining eye.

During early development, interactions between the two eyes are critical in the formation of eye-specific domains within the lateral geniculate nucleus and the visual cortex. When monocular enucleation is done early in prenatal life, it induces remarkable anatomical and functional reorganizations of the visual pathways. Behavioral data have shown a loss in sensitivity to low-spatial-frequency gratings in cats. To correlate the behavioral observations with a possible change in the analysis of contrast at the level of primary visual areas we recorded visual evoked potentials at the 17/18 border in two cats enucleated prenatally (gestational age at enucleation, 39-42 days), three neonatal, two control animals, and one animal with a surgical removal of Y-ganglion fibers. Our results show a strong attenuation in the amplitude of response at all contrast values for gratings of low spatial frequency in prenatally enucleated cats, whereas neonatally enucleated and control animals present responses of comparable amplitude. We conclude that the behavioral results reflect the reduced sensitivity for low frequencies of visual cortical neurons. In addition, we define a critical period for the development of the contrast-sensitivity function that seems to be limited to the prenatal gestation period. We suggest that the prenatal interruption of binocular interactions leads to a functional elimination of the Y-ganglion system.

Células-tronco de membrana amniótica de cão como terapia alternativa para o tratamento de ceratoconjuntivite seca em cães

A Ceratoconjuntivite Seca (KCS Keratoconjunctivitis Sicca) é uma desordem imunomediada e resulta de alterações do componente aquoso do filme lacrimal e da deficiência dos componentes lipídicos e mucoso.Seu diagnóstico é baseado no Teste Lacrimal de Schirmer (TLS) e no Teste de Ruptura do Filme Lacrimal (TRFL) e tem como sinais clínicos: secreção mucopurulenta, hiperemia conjuntival, blefaroespasmos, fotofobia, incômodo, dor, vascularização, opacidade corneana e pigmentação, além de cegueira em casos avançados. O tratamento convencional consiste em aplicações diárias de Ciclosporina 0,2% ou Tacrolimus 0,03% (pomada ou colírio oftálmicos), que apesar de controlar a doença, são custosos, não curativos e exigem alto comprometimento da interação paciente-proprietário. A terapia celular usando células-tronco (CT) traz uma nova esperança para doenças sem tratamento efetivo. Neste trabalho utilizamos CT mesenquimais (CTM) obtidas a partir de membrana amniótica (CTMA) de cães obtidas a partir do descarte destes tecidos em campanhas de castrações em diferentes tempos gestacionais, sem formação tumoral quando submetidas ao teste tumorigênico durante 60 dias. Dois animais com KCS crônica foram tratados com duas injeções de CTMA com intervalo de 30 dias, sendo a primeira de 0,5x106 células e a segunda de 1x106 células em cada glândula. Na segunda semana após a terapia foi observado aumento da TLS sugerindo um benéficio da terapia que foi diminuindo com o passar das semanas. O TRFL oscilou durante os testes e não apresentou diferenças significativas. A terapia celular utilizando CTMA de cães melhorou a condição ocular nos dois casos em momentos e parâmetros variados, com repercussão na melhoria da superfície, mas não houve regressão do quadro clínico. Investigações futuras em estágios menos avançados da doença podem ajudar a elucidar os mecanismos pelos quais esse efeito foi obtido

Privy Private Eye: A Guidebook for Travelers Who Have to Go

This creative Capstone project, Privy Private Eye: A Guidebook for Travelers Who Have to Go, contains a nonfiction compendium of brief reviews of public restrooms in the Dallas, Texas area. To inform readers about facilities that are safe (and a few that should be avoided), Privy Private Eye contains reviews and ratings of restrooms in gas stations, restaurants, and retail centers. These appraisals will be featured in a full-length manuscript that may be published in the near future as a travel guide. Also contained herein, before the creative portion of the project itself, is a reflective paper describing the project, its creation, and its position within the context of published travel guides.

Kinematics of eyelid movement and eye retraction in the blinking

Resumen del póster expuesto en el 6th EOS Topical Meeting on Visual and Physiological Optics (EMVPO 2012), Dublín, 20-22 Agosto 2012.

Kinematics of eyelid movement and eye retraction in the blinking [Poster]

Póster presentado en el 6th EOS Meeting on Visual and Physiological Optics (EMVPO 2012), Dublín, 20-22 Agosto 2012.

Analysis of fixational eye micromovements through pupil tracking

Póster presentado en OPTYKA Optical Fair 2012, Poznan, Polonia, 9-10 noviembre 2012.

Intrasubject repeatability in keratoconus-eye measurements obtained with a new Scheimpflug photography–based system

Purpose: To evaluate in keratoconus eyes the intrasubject repeatability of anterior and posterior corneal curvature and of other anterior segment anatomic measurements obtained with a new topography system combining Scheimpflug-photography and Placido-disk technology. Setting: Vissum Corporation, Alicante, Spain. Design: Evaluation of technology. Methods: All keratoconus eyes had a comprehensive ophthalmologic examination including analysis with the Sirius system. Three consecutive measurements were obtained to assess the intrasubject repeatability of the following parameters: anterior and posterior corneal curvature and shape factor, white-to-white (WTW) corneal diameter, central and minimum corneal thickness, and anterior chamber depth (ACD). The within-subject standard deviation (Sw) and intraclass correlation coefficient (ICC) were calculated. Results: This study comprised 61 eyes of 61 patients ranging in age from 14 to 64 years. For anterior and posterior corneal curvatures and power vector components, the Sw was 0.29 mm or less in all cases. The ICC was above 0.990 in all cases except the flattest curvature of the posterior corneal surface at 3.0 mm, which was 0.840 (moderate agreement), and the posterior power vector J0, which was 0.665 (poor agreement), 0.752, and 0.758 (moderate agreement) for 3.0 mm, 5.0 mm, and 7.0 mm, respectively. In shape factor measurements, the Sw was 0.12 or less in all cases and the ICC ranged between 0.989 and 0.999. Pachymetry, ACD, and WTW had ICC values very close to 1. Conclusion: The new topography system provided repeatable measurements of corneal shape and other anatomic parameters in eyes with keratoconus.

Correlation of the Corneal Toricity Between Anterior and Posterior Corneal Surfaces in the Normal Human Eye

Purpose: To evaluate the correlation of the magnitude of corneal toricity and power vector components of both corneal surfaces measured with a Scheimpflug photography-based system. Methods: A total of 117 healthy normal eyes of 117 subjects selected randomly with ages ranging from 7 to 80 years were included. All eyes received an anterior segment and corneal analysis with the Sirius system (CSO) evaluating the anterior and posterior mean toricity for 3 and 7 mm (aAST and pAST). The vector components J0 and J45 as well as the overall strength blur (B) were calculated for each keratometric measurement using the procedure defined by Thibos and Horner. Results: The coefficient of correlation between aAST and pAST was 0.52 and 0.62 and the mean anteroposterior ratio for toricity was 0.46 ± 0.39 and 0.57 ± 0.75 for 3 and 7 mm, respectively. These ratios correlated significantly with aAST, anterior corneal J0, and manifest refraction J0 (r ≥ 0.39, P < 0.01). The coefficient of correlation was 0.69 and 0.81 between anterior and posterior J0 for 3 and 7 mm, respectively. For J45, the coefficients were 0.62 and 0.71, respectively. The linear regression analysis revealed that the pAST and power vectors could be predicted from the anterior corneal data (R2 ≥ 0.40, P < 0.01). Conclusions: The toricity and astigmatic power vector components of the posterior corneal surface in the human healthy eye are related to those of the anterior and therefore can be predicted consistently from the anterior toricity and astigmatic power vectors.

Modeling the role of fixational eye movements in real-world scenes

Our eyes never remain still. Even when we stare at a fixed point, small involuntary movements take place in our eyes in an imperceptible manner. Researchers agree on the presence of three main contributions to eye movements when we fix the gaze: microsaccades, drifts and tremor. These small movements carry the image across the retina stimulating the photoreceptors and thus avoiding fading. Nowadays it is commonly accepted that these movements can improve the discrimination performance of the retina. In this paper, several retina models with and without fixational eye movements were implemented by mean of RetinaStudio tool to test the feasibility of these models to be incorporated in future neuroprostheses. For this purpose each retina model has been stimulated with natural scene images in two experiments. Results are discussed from the point of view of a neuroprosthesis development.

Advanced techniques for the human eye study: ocular aberrometry

Lectures about the course module "Advanced techniques for the human eye study: ocular aberrometry".

A high-resolution binocular video-oculography system: assessment of pupillary light reflex and detection of an early incomplete blink and an upward eye movement

Background: The pupillary light reflex characterizes the direct and consensual response of the eye to the perceived brightness of a stimulus. It has been used as indicator of both neurological and optic nerve pathologies. As with other eye reflexes, this reflex constitutes an almost instantaneous movement and is linked to activation of the same midbrain area. The latency of the pupillary light reflex is around 200 ms, although the literature also indicates that the fastest eye reflexes last 20 ms. Therefore, a system with sufficiently high spatial and temporal resolutions is required for accurate assessment. In this study, we analyzed the pupillary light reflex to determine whether any small discrepancy exists between the direct and consensual responses, and to ascertain whether any other eye reflex occurs before the pupillary light reflex. Methods: We constructed a binocular video-oculography system two high-speed cameras that simultaneously focused on both eyes. This was then employed to assess the direct and consensual responses of each eye using our own algorithm based on Circular Hough Transform to detect and track the pupil. Time parameters describing the pupillary light reflex were obtained from the radius time-variation. Eight healthy subjects (4 women, 4 men, aged 24–45) participated in this experiment. Results: Our system, which has a resolution of 15 microns and 4 ms, obtained time parameters describing the pupillary light reflex that were similar to those reported in previous studies, with no significant differences between direct and consensual reflexes. Moreover, it revealed an incomplete reflex blink and an upward eye movement at around 100 ms that may correspond to Bell’s phenomenon. Conclusions: Direct and consensual pupillary responses do not any significant temporal differences. The system and method described here could prove useful for further assessment of pupillary and blink reflexes. The resolution obtained revealed the existence reported here of an early incomplete blink and an upward eye movement.

Clinical Characterization of Asymptomatic or Minimally Symptomatic Young Patients Showing Signs Compatible With Dry Eye: A Pilot Study

Purpose: To evaluate and characterize the clinical profile of young asymptomatic or minimally symptomatic patients without diagnosis of dry eye but showing signs compatible with dry eye syndrome (DES). Methods: Prospective study including a total of 50 consecutive subjects with ages ranging from 18 to 40 years that were identified as asymptomatic or minimally symptomatic by means of the Ocular Surface Disease Index (OSDI) (score of <22). In all patients, a complete battery of tests for the diagnosis of DES was performed including the evaluation of the tear film break-up time (TFBUT), the level of corneal and conjunctival staining, and the eyelid and Meibomian morphology. Results: The OSDI score was significantly higher in women than in men (median: 12.5 vs. 5.3, P=0.01). Low grades of ocular surface staining, dysfunction of Meibomian gland expression, and alteration of quality of Meibomian secretions were observed in 56%, 58%, and 84% of eyes, respectively. More eyes with some dysfunction of Meibomian gland expressibility had a TFBUT less than 5 sec (P=0.033). A statistically significant difference in the OSDI score was found between patients with and without systemic allergies (P=0.036) and between male and female (P=0.01). Likewise, the OSDI score was significantly higher in those women wearing contact lenses compared with those not wearing them (P=0.012). Conclusions: Asymptomatic or minimally symptomatic young subjects may present low grades of clinical signs compatible with DES, with a trend to more symptomatology in women and allergic patients. These outcomes should be confirmed in future studies with larger samples.

Birds eye view of trolley routes in New England, 1904 (Raster Image)

This layer is a georeferenced raster image of the historic paper map entitled: Trolley wayfinder, birds eye view of trolley routes in New England, published by the New England Street Railway Club, 1904. This is a perspective map not drawn to scale. Covers eastern portion of New England from Lewiston, Maine, to Newport, Rhode Island. The image inside the map neatline is georeferenced to the surface of the earth and fit to the Massachusetts State Plane Coordinate System, Mainland Zone (in Feet) (Fipszone 2001). All map collar and inset information is also available as part of the raster image, including any inset maps, profiles, statistical tables, directories, text, illustrations, or other information associated with the principal map. This map shows features such as steam railroads, electric railroads, parks, buildings, drainage, and more. Relief and some features are shown pictorially. Includes 7 insets. This layer is part of a selection of digitally scanned and georeferenced historic maps of Massachusetts from the Harvard Map Collection. These maps typically portray both natural and manmade features. The selection represents a range of regions, originators, ground condition dates (1755-1922), scales, and purposes. The digitized selection includes maps of: the state, Massachusetts counties, town surveys, coastal features, real property, parks, cemeteries, railroads, roads, public works projects, etc.