The successful use of a search strategy improves with visuospatial working memory in 2- to 4.5-year-olds.

Using spatial cues such as shape, orientation, and pattern aids visuospatial working memory because it allows strategies that reduce the load on this cognitive resource. One such strategy, namely taking advantage of patterned spatial distributions, remains understudied to date. This strategy demands keeping track of already-searched locations and excluding them from further search and so correlates with visuospatial working memory. The use of such strategies should, in principle, develop in early childhood, but because most studies focus on chunking, the development of other strategies reducing the load on working memory is understudied in young children. Therefore, in this study we tested whether children aged 2 to 4.5 years (N = 97) could take advantage of spatial cues in their search and whether this ability correlated with their age, verbal ability, and visuospatial working memory. The results showed that the ability to use a patterned spatial distribution (searching a row of locations from one side to the other instead of a random search) significantly improved with visuospatial working memory but not with age or verbal ability. These results suggest that visuospatial abilities may rapidly develop from 2 to 4.5 years of age, and given their impact on later mathematic achievement, demand increased attention in cognitive developmental research and early childhood education.

Single-cell RNA sequencing unravels the transcriptional network underlying zebrafish retina regeneration.

In the lesioned zebrafish retina, Müller glia produce multipotent retinal progenitors that generate all retinal neurons, replacing lost cell types. To study the molecular mechanisms linking Müller glia reactivity to progenitor production and neuronal differentiation, we used single-cell RNA sequencing of Müller glia, progenitors and regenerated progeny from uninjured and light-lesioned retinae. We discover an injury-induced Müller glia differentiation trajectory that leads into a cell population with a hybrid identity expressing marker genes of Müller glia and progenitors. A glial self-renewal and a neurogenic trajectory depart from the hybrid cell population. We further observe that neurogenic progenitors progressively differentiate to generate retinal ganglion cells first and bipolar cells last, similar to the events observed during retinal development. Our work provides a comprehensive description of Müller glia and progenitor transcriptional changes and fate decisions in the regenerating retina, which are key to tailor cell differentiation and replacement therapies for retinal dystrophies in humans.

Preschool teachers' pedagogical content knowledge predicts willingness to scaffold early science learning.

BACKGROUND: The importance of diagnostic and scaffolding activities for early science learning has been shown consistently. However, preschool teachers scarcely engage in them. We developed an instrument to assess preschool teachers' willingness to engage in diagnostic and scaffolding activities in science learning situations and examined its relation with teachers' knowledge, beliefs and practice. AIMS: We validate an instrument to assess willingness to engage in scaffolding and diagnostic activities and study the interplay between willingness, learning beliefs, content knowledge (CK) and pedagogical content knowledge (PCK) in the context of science learning, particularly block play. SAMPLE(S): A total of N = 151 preschool teachers from 41 kindergartens in Germany participated in our study. METHODS: Preschool teachers completed a questionnaire, which took approximately 1 hour of time. We drew a subsample of N = 73 teachers and observed their practice during a 30 min block play episode. RESULTS: With our instrument, we were able to distinguish between preschool teachers' willingness to diagnose and to scaffold. Preschool teachers' co-constructivist beliefs and PCK predicted willingness to engage in diagnosing, PCK also predicted willingness to engage in scaffolding. Associations between learning beliefs and practice were inconsistent. CONCLUSIONS: Our study highlights aspects of the association between preschool teachers' PCK and their willingness to engage in diagnosing and scaffolding. However, we found inconsistencies between preschool teachers' beliefs and practice, which call for further clarification.

Fostering preservice teachers' expectancies and values towards computational thinking.

Theory: Digital technologies have become an integral part of everyday life that children are exposed to. Therefore, it is important for children to acquire an understanding of these technologies early on by teaching them computational thinking (CT) as a part of STEM. However, primary school teachers are often reluctant to teach CT. Expectancy-value theory suggests that motivational components play an important role in teaching and learning. Thus, one hindrance to teachers' willingness to teach CT might be their low expectancies of success and high emotional costs, e.g., anxiety towards CT. Thus, introducing preservice teachers to CT during their university years might be a promising way to support their expectancies and values, while simultaneously alleviating their emotional costs. Prior CT competences might contribute to these outcomes. Aims: We investigated whether a specifically designed seminar on CT affected preservice teachers' expectancies and values towards programming.Method: A total of 311 German primary school and special education preservice teachers took part in the study. The primary school preservice teachers received a seminar on CT and programming with low-threshold programming tasks, while the special education teachers served as a baseline group. The seminar was specifically designed to enhance expectancies and values and decrease emotional costs, following implications of research on expectancy-value theory. Results: The preservice teachers who visited the seminar gained higher expectancies and values towards CT and programming compared to the baseline group. Moreover, their emotional costs decreased. CT was positively related to change in expectancies and values and negatively related to emotional costs. Discussion: Interventions with low-threshold programming tasks can support primary school preservice teachers in finding trust in their abilities and values towards CT. Moreover, their anxiety towards CT and programming can be alleviated. Thus, first steps in preparing preservice teachers to teach CT in their future classrooms can be taken in university.

[Avoidable mortality-a new indicator version for prevention reporting]. / Vermeidbare Sterblichkeit ­ Neufassung eines Indikators für die Präventionsberichterstattung.

BACKGROUND: "Avoidable mortality" is used as an indicator in health reporting. The indicator aggregates selected causes of death. In Germany two versions exist, both of which are no longer up to date. A new version is proposed. METHODS: The new version is based on preparatory work on the European level. The feasibility and plausibility of a common OECD Eurostat list are examined using official statistics data from Bavaria from 2016 to 2018. The analysis includes an examination of the variability over time and within the Bavarian administrative districts, as well as possible systematic errors through regional differences in coding behaviour or changes over time. RESULTS: The OECD Eurostat list can be implemented at the regional level with only minor modifications. The age-standardized avoidable mortality in Bavaria in 2018 is almost 23 deaths per 10,000 inhabitants, with preventable deaths by far outweighing treatable deaths. For men, the death rate due to avoidable causes is 30 per 10,000 male inhabitants, which is almost twice as high as that for women (16 per 10,000 female inhabitants). The regional findings on avoidable mortality are consistent with findings on regional health from other studies. DISCUSSION AND CONCLUSION: The results do not indicate a threat to reliability due to random fluctuation or systematic methodological errors. The new version is recommended for application in health reporting.

Visual Function is Gradually Restored During Retina Regeneration in Adult Zebrafish.

In comparison to mammals, zebrafish are able to regenerate many organs and tissues, including the central nervous system (CNS). Within the CNS-derived neural retina, light lesions result in a loss of photoreceptors and the subsequent activation of Müller glia, the retinal stem cells. Müller glia-derived progenitors differentiate and eventually restore the anatomical tissue architecture within 4 weeks. However, little is known about how light lesions impair vision functionally, as well as how and to what extent visual function is restored during the course of regeneration, in particular in adult animals. Here, we applied quantitative behavioral assays to assess restoration of visual function during homeostasis and regeneration in adult zebrafish. We developed a novel vision-dependent social preference test, and show that vision is massively impaired early after lesion, but is restored to pre-lesion levels within 7 days after lesion. Furthermore, we employed a quantitative optokinetic response assay with different degrees of difficulty, similar to vision tests in humans. We found that vision for easy conditions with high contrast and low level of detail, as well as color vision, was restored around 7-10 days post lesion. Vision under more demanding conditions, with low contrast and high level of detail, was regained only later from 14 days post lesion onwards. Taken together, we conclude that vision based on contrast sensitivity, spatial resolution and the perception of colors is restored after light lesion in adult zebrafish in a gradual manner.

The Impact of a Construction Play on 5- to 6-Year-Old Children's Reasoning About Stability.

THEORY: Young children have an understanding of basic science concepts such as stability, yet their theoretical assumptions are often not concerned with stability. The literature on theory theory and theory-evidence coordination suggests that children construct intuitive theories about their environment which can be adjusted in the face of counterevidence that cannot be assimilated into the prior theory. With increasing age, children acquire a Center theory when balancing objects and try to balance every object at their middle, succeeding with symmetrical objects. Later, they acquire the basic science concept of stability through learning that the weight distribution of an object is of importance. Thus, they acquire a Mass theory and succeed in balancing asymmetrical objects as well. Fluid and crystallized intelligence might contribute to children's acquisition of Mass theory. Moreover, their Mass theory might be supported by implementing a playful intervention including (a) material scaffolds and (b) verbal scaffolds. AIMS: We investigated which theories children have about stability and whether these theories can be adjusted to Mass theory by implementing a playful intervention. METHOD: A total of 183 5- to 6-year-old children took part in the study with a pre-post-follow-up intervention design. Children's Mass theory was assessed with an interview in which children explained constructions' stabilities. The children received a playful intervention with two differing degrees of scaffolding (material scaffolds or material + verbal scaffolds) or no scaffolding. RESULTS: At first few children used a Mass theory to explain their reasoning. However, after being confronted with counterevidence for the asymmetrical constructions, children changed their explanation and applied a Mass theory. More children in the play group with the highest degree of scaffolding, i.e., material + verbal scaffolds, acquired a Mass theory compared to the other groups. Fluid as well as crystallized intelligence contributed to children's acquisition of a Mass theory. DISCUSSION: Counterevidence can support children in their acquisition of a Mass theory. A playful intervention with scaffolding supports children even more.

Single cell sequencing of radial glia progeny reveals the diversity of newborn neurons in the adult zebrafish brain.

Zebrafish display widespread and pronounced adult neurogenesis, which is fundamental for their regeneration capability after central nervous system injury. However, the cellular identity and the biological properties of adult newborn neurons are elusive for most brain areas. Here, we have used short-term lineage tracing of radial glia progeny to prospectively isolate newborn neurons from the her4.1+ radial glia lineage in the homeostatic adult forebrain. Transcriptome analysis of radial glia, newborn neurons and mature neurons using single cell sequencing identified distinct transcriptional profiles, including novel markers for each population. Specifically, we detected two separate newborn neuron types, which showed diversity of cell fate commitment and location. Further analyses showed that these cell types are homologous to neurogenic cells in the mammalian brain, identified neurogenic commitment in proliferating radial glia and indicated that glutamatergic projection neurons are generated in the adult zebrafish telencephalon. Thus, we prospectively isolated adult newborn neurons from the adult zebrafish forebrain, identified markers for newborn and mature neurons in the adult brain, and revealed intrinsic heterogeneity among adult newborn neurons and their homology with mammalian adult neurogenic cell types.

Measuring preschool children's knowledge of the principle of static equilibrium in the context of building blocks: Validation of a test instrument.

BACKGROUND: Preschoolers' knowledge of the principle of static equilibrium is an important research focus for understanding children's science content knowledge. Hitherto studies have mainly used behavioural observation with small samples. Thus, extending these studies with a validated test instrument is desirable. AIMS: The aim was to validate an instrument (the Centre-of-Mass Test), which is concerned with preschoolers' knowledge of the principle of static equilibrium, using item response theory. In Study 1, the construct structure was tested, and in Study 2, its relationship with stabilities of symmetrical blocks, figural reasoning, figural perception, mental rotation, level of interest, self-concept, motivation, and language capacity was investigated. SAMPLES: A total of 217 five- and six-year-old children participated in Study 1 and 166 five- and six-year-old children in Study 2. METHODS: All tests were administered as paper-pencil picture tests in groups and single interviews. RESULTS: In Study 1, the Centre-of-Mass Test's conformity with a 1PL-testlet model with an overall knowledge of static equilibrium and with two subtests, estimation of stable and unstable constructions, was confirmed. Using a 95% binomial distribution, children were categorized into three knowledge categories: geometrical-centre, centre-of-mass, and undifferentiated knowledge. In Study 2, knowledge of the principle of static equilibrium showed positive correlations with figural perception and reasoning, language capacity, and estimation of the stabilities of symmetrical objects. CONCLUSIONS: The Centre-of-Mass Test measures knowledge of the principle of static equilibrium as a unidimensional construct and mirrors preschoolers' estimations found in previous studies. The acquisition of a more sophisticated static equilibrium knowledge is related to spatial knowledge and language capacity.

The Restorative Value of the Urban Environment: A Systematic Review of the Existing Literature.

BACKGROUND: Stress poses a major issue in our modern society, making restoration an important research focus. Restoration likelihood has mostly been observed in nature, which was compared with urban environments that have little restorative potential, eg, industrial areas. However, many people reside in and need to find restoration in cities. The main aim of this review is to summarize research that has focused on investigating restoration possibilities in urban environments and the environmental elements interacting with the restoration likelihood of an urban environment. METHOD: This review focuses on studies addressing the topic of restoration possibilities in urban settings in built and human-made natural urban environments. The studies were searched via Google Scholar, PsycINFO, PsycARTICLES, and PSYNDEX. All studies concerned with restoration in urban environments were included. However, studies concerned with nonoriginal data, solely investigating effects of natural environments or treating urban environments as a control for restoration in nature, were excluded from the review. Overall, 39 studies corresponded to the criteria and were included. RESULTS: Natural elements in urban environments have a restorative potential and can increase the restorativeness of urban settings. Furthermore, built urban environments vary in their restorative potential, but promising results have been uncovered as well. Architectural elements, cultural, and leisure areas had a restorative value, whereas the findings on streets and residential areas differ. In sum, many urban locations can have restorative effects, but these effects may be influenced by factors such as cultural background, age, social components, and individual dispositions. DISCUSSION: Certain urban environments hold a restorative potential. However, the literature on restoration in urban environments is still quite scarce and therefore has been of little practical use. Even though applying the findings to real-life environments is desirable, it might prove difficult, considering the overall sparse evidence. More research on the predictors of restoration likelihood (eg, social factors), generational and cultural differences, and comparisons between natural and urban environments is recommended.

Deaths amenable to health care: Converging trends in the EU?

Amenable mortality has been recently included in the joint monitoring tool by the European Commission and Member States to assess a country's health system performance. Amenable deaths are premature deaths, which should not have occurred at this stage in the light of timely and effective health care. This paper recalculated annual amenable mortality rates for 28EU countries and the EU for the period 1994-2013 based on the recently published list of deaths amenable to health care by Eurostat. Thereby, it offers a consistent calculation of amenable mortality across European Member States and provides time series data on amenable mortality. In addition, a sensitivity analysis of the amenable mortality indicator for varying age limits and attributional weights of circulatory system diseases is carried out. While large improvements were made in reducing amenable deaths in all European countries, great variations persist among Member States. Most of the decreases in amenable mortality are explained by a substantial reduction of deaths due to circulatory system diseases. In addition, even in countries with good national performance on amenable mortality, sub-national analysis shows that great regional disparities exist. The sensitivity analysis revealed that for the large majority of countries results are stable across different attributional weights used for ischaemic heart diseases and cerebrovascular diseases.

Henle fiber layer phase retardation changes associated with age-related macular degeneration.

PURPOSE: To quantify and compare phase retardation amplitude and regularity associated with the Henle fiber layer (HFL) between nonexudative AMD patients and age-matched controls using scanning laser polarimetry (SLP) imaging. METHODS: A scanning laser polarimeter was used to collect 15 × 15° macular-centered images in 25 patients with nonexudative AMD and 25 age-matched controls. Raw image data were used to compute macular phase retardation maps associated with the HFL. Consecutive, annular regions of interest from 0.5 to 3.0° eccentricity, centered on the fovea, were used to generate intensity profiles from phase retardation data and analyzed with two complementary techniques: a normalized second harmonic frequency (2f) of the fast Fourier Transform (FFT) analysis and a curve fitting analysis using a 2f sine function. Paired t-tests were used to compare the normalized 2f FFT magnitude at each eccentricity between the two groups, the eccentricity that yielded the maximum normalized 2f FFT between paired individuals across the two groups, and curve fitting RMS error at each eccentricity between the two groups. RESULTS: Normalized 2f FFT components were lower in the AMD group at each eccentricity, with no difference between the two groups in the maximum normalized 2f FFT component eccentricity. The root-mean-square (RMS) error from curve fitting was significantly higher in the AMD group. CONCLUSIONS: Phase retardation changes in the central macula indicate loss and/or structural alterations to central cone photoreceptors in nonexudative AMD patients. Scanning laser polarimetry imaging is a noninvasive method for quantifying cone photoreceptor changes associated with central macular disease.

Experimental study on the behavior of primary human osteoblasts on laser-cused pure titanium surfaces.

Mandibular tumor resection can lead to a mandibular segmental defect. LaserCUSING® is used to produce a mandibular implant, designed to be identical to the shape of the mandibular defect. Novel microrough surfaces result from this generative technology. In the current study, the behavior of human osteoblasts on untreated laser-cused titanium specimens or on specimens conditioned with different blasting agents was analyzed. The conditioning of these specimens resulted in surfaces with graded roughness. White light confocal microscopy and single-cell force spectroscopy were used to characterize the surface of the specimens and to quantify the initial adhesion of primary human osteoblasts to the specimens, respectively. Furthermore, cell growth, viability, apoptosis as well as mineralization of the specimens were analyzed over a time-period of 2 months. Compared to specimens that were treated with blasting agents, untreated specimens had the highest surface roughness. Quantitative SCFS measurements demonstrated that the adhesion of human primary osteoblasts was the highest on these specimens. Additionally, the untreated specimens allowed the highest number of osteoblasts to colonize. Mineralization studies showed increasing calcium and phosphor elemental composition for all specimen series. It can be concluded that untreated laser-cused titanium specimens are superior to promote the initial adhesion and subsequent colonization by osteoblast cells.

Characterization of light lesion paradigms and optical coherence tomography as tools to study adult retina regeneration in zebrafish.

Light-induced lesions are a powerful tool to study the amazing ability of photoreceptors to regenerate in the adult zebrafish retina. However, the specificity of the lesion towards photoreceptors or regional differences within the retina are still incompletely understood. We therefore characterized the process of degeneration and regeneration in an established paradigm, using intense white light from a fluorescence lamp on swimming fish (diffuse light lesion). We also designed a new light lesion paradigm where light is focused through a microscope onto the retina of an immobilized fish (focused light lesion). Focused light lesion has the advantage of creating a locally restricted area of damage, with the additional benefit of an untreated control eye in the same animal. In both paradigms, cell death is observed as an immediate early response, and proliferation is initiated around 2 days post lesion (dpl), peaking at 3 dpl. We furthermore find that two photoreceptor subtypes (UV and blue sensitive cones) are more susceptible towards intense white light than red/green double cones and rods. We also observed specific differences within light lesioned areas with respect to the process of photoreceptor degeneration: UV cone debris is removed later than any other type of photoreceptor in light lesions. Unspecific damage to retinal neurons occurs at the center of a focused light lesion territory, but not in the diffuse light lesion areas. We simulated the fish eye optical properties using software simulation, and show that the optical properties may explain the light lesion patterns that we observe. Furthermore, as a new tool to study retinal degeneration and regeneration in individual fish in vivo, we use spectral domain optical coherence tomography. Collectively, the light lesion and imaging assays described here represent powerful tools for studying degeneration and regeneration processes in the adult zebrafish retina.

Retrobulbar blood flow and visual field alterations after acute ethanol ingestion.

BACKGROUND: The purpose of this study was to test the effect of ethyl alcohol on the koniocellular and magnocellular pathway of visual function and to investigate the relationship between such visual field changes and retrobulbar blood flow in healthy subjects. METHODS: In 12 healthy subjects (mean age 32 ± 4 years), color Doppler imaging, short-wavelength automated perimetry, and frequency doubling perimetry was performed before and 60 minutes after oral intake of 80 mL of 40 vol% ethanol. Mean and pattern standard deviations for short-wavelength automated and frequency doubling perimetry were assessed. End diastolic velocity (EDV) and peak systolic velocity (PSV) were measured in the central retinal and ophthalmic arteries using color Doppler imaging. Systemic blood pressure, heart rate, intraocular pressure, and blood alcohol concentration were determined. RESULTS: Mean PSV and EDV in the central retinal artery showed a significant increase after alcohol intake (P = 0.03 and P = 0.02, respectively). Similarly, we found a significant acceleration of blood flow velocity in the ophthalmic artery (P = 0.02 for PSV; P = 0.04 for EDV). Mean intraocular pressure decreased by 1.0 mmHg after alcohol ingestion (P = 0.01). Retinal sensitivity in short-wavelength automated perimetry did not alter, whereas in frequency doubling perimetry, the mean deviation decreased significantly. Systolic and diastolic blood pressure did not change significantly. Mean blood alcohol concentration was 0.38 ± 0.16 g/L. CONCLUSION: Although ethanol is known to cause peripheral vasodilation, our subjects had no significant drop in systemic blood pressure. However, a significant increase of blood flow velocity was seen in the retrobulbar vessels. Regarding visual function, moderate alcohol consumption led to reduced performance in the magnocellular visual system tested by frequency doubling perimetry, but had no effect on short-wavelength automated perimetry.

A prospective 10-year study of metal ceramic single crowns and fixed dental prosthesis retainers in private practice settings.

STATEMENT OF PROBLEM: Metal ceramic restorations are widely used in prosthodontics, but long-term data on their clinical performance in private practice settings based on prospective trials are sparse. PURPOSE: This clinical trial was designed to provide realistic long-term survival rates for different outcomes related to tooth loss, crown loss, and metal ceramic defect. MATERIAL AND METHODS: Ninety-five participants were provided with 190 noble metal ceramic single crowns and 138 participants with 276 fixed dental prosthesis retainer crowns on vital posterior teeth. Follow-up examinations were scheduled 2 weeks after insertion, annually up to 8 years, and after 10 years. Kaplan-Meier survival analyses, Mantel-Cox logrank tests, and Cox regression analyses were conducted. RESULTS: Because of variations in the time of the last examinations, the maximum observation period was 12.1 years. For the primary outcome 'loss of crown or tooth', the Kaplan-Meier survival rate was 94.3% ±1.8% (standard error) at 8.0 years (last outcome event) for single crowns and 94.4% ±1.5% at 11.0 years for fixed dental prosthesis retainer crowns. The difference between the survival functions was not significant (P>.05). For the secondary outcome 'metal ceramic defect', the survival rate was 88.8% ±3.2% at 11.0 years for single crowns and 81.7% ±3.5% at 11.0 years for fixed dental prosthesis retainer crowns. In Cox regression models, the only significant covariates for the outcome event 'metal ceramic defect' were bruxism in the medical history (single crowns) and signs and symptoms of bruxism (fixed dental prosthesis retainer crowns) with hazard ratios of 3.065 (95% CI 1.063 - 8.832) and 2.554 (95% CI 1.307 - 4.992). CONCLUSIONS: Metal ceramic crowns provided in private practice settings show good longevity. Bruxism appears to indicate a risk for metal ceramic defects.

Foveal localization in non-exudative AMD using scanning laser polarimetry.

PURPOSE: To determine whether custom scanning laser polarimetry (SLP) images, differing in polarization content, can be used to accurately localize the fovea in the presence of non-exudative age-related macular degeneration (AMD). To determine whether alterations to the foveal structure in non-exudative AMD significantly disrupts the birefringent Henle fiber layer, responsible for the macular cross pattern in some SLP images. To determine whether phase retardation information, specifically color-coded information representing its magnitude and axis, allow better foveal localization than images including retardation amplitude only. METHODS: SLP images were acquired in 25 AMD subjects and 25 age-matched controls. Raw data were used to generate five custom image types differing in polarization content. The foveal location was marked by three graders in each image type for each subject. The difference in variability was compared between the AMD subjects and matched controls. We further determined whether the orientation of Henle fiber layer phase retardation improved localization in 10 subjects with the highest variability in images including only phase retardation amplitude. RESULTS: Images that differed in polarization content led to strikingly different visualizations of AMD pathology. The Henle fiber layer remained sufficiently intact to assist in fovea localization in all subjects but with more variability in the AMD group. For both the AMD and matched control group, images containing birefringence amplitude and orientation information reduced the amount of intragrader, intergrader, and interimage variability for estimating foveal location. CONCLUSIONS: The disruption in Henle fiber birefringence was evident in the eyes with AMD but nevertheless was sufficient to help in foveal localization despite macular pathology. Phase retardation amplitude and axis of orientation can be a useful tool in foveal localization in patients with AMD.

Fgf signaling is required for photoreceptor maintenance in the adult zebrafish retina.

Fibroblast growth factors (Fgf) are secreted signaling molecules that have mitogenic, patterning, neurotrophic and angiogenic properties. Their importance during embryonic development in patterning and morphogenesis of the vertebrate eye is well known, but less is known about the role of Fgfs in the adult vertebrate retina. To address Fgf function in adult retina, we determined the spatial distribution of components of the Fgf signaling pathway in the adult zebrafish retina. We detected differential expression of Fgf receptors, ligands and downstream Fgf targets within specific retinal layers. Furthermore, we blocked Fgf signaling in the retina, by expressing a dominant negative variant of Fgf receptor 1 conditionally in transgenic animals. After blocking Fgf signaling we observe a fast and progressive photoreceptor degeneration and disorganization of retinal tissue, coupled with cell death in the outer nuclear layer. Following the degeneration of photoreceptors, a profound regeneration response is triggered that starts with proliferation in the inner nuclear layer. Ultimately, rod and cone photoreceptors are regenerated completely. Our study reveals the requirement of Fgf signaling to maintain photoreceptors and for proliferation during regeneration in the adult zebrafish retina.

Ocular pulse amplitude before and after cataract surgery.

PURPOSE: To investigate the impact of cataract surgery on the association of the ocular pulse amplitude (OPA) and intraocular pressure (IOP) with respect to the interpretation of OPA as an estimate of ocular blood flow. METHODS: Twenty-four patients with cataract were included in a clinical study. OPA was measured using dynamic contour tonometry (DCT, Pascal(®), SMT Swiss Microtechnology AG, Switzerland). IOP was measured by means of Goldmann applanation tonometry (IOP GAT) and DCT (IOP DCT). All measurements were performed before and one day after cataract surgery. RESULTS: At baseline, OPA was correlated to IOP GAT (r = 0.67, P = 0.0002) and IOP DCT (r = 0.82, P < 0.0001), but not to age or axial length. Postoperative OPA was correlated to IOP GAT (r = 0.67, P = 0.0002) and IOP DCT (r = 0.65, P = 0.0004). In 17 patients, IOP GAT decreased after surgery (IOP DCT n = 14), whereas an increase was apparent in seven patients (IOP DCT n = 10). The mean absolute deviation of IOP GAT pre- to post-surgery was 4.54 mmHg ± 2.47 (range 1-10 mmHg) and 5.4 mmHg ± 3.2 (range 1.1-13.1 mmHg) for IOP DCT. The changes of OPA were significantly correlated to changes in IOP GAT (r = 0.48, P = 0.017) and IOP DCT (r = 0.60, P = 0.001). IOP GAT and IOP DCT changes were not correlated to changes in corneal thickness. CONCLUSIONS: The OPA measured with the Pascal(®) device seems to be dependent on IOP changes. Particular caution should be taken in the interpretation of OPA in estimating pulsatile ocular blood flow.

Determination of foveal location using scanning laser polarimetry.

The fovea is the retinal location responsible for our most acute vision. There are several methods used to localize the fovea, but the fovea is not always easily identifiable. Landmarks used to determine the foveal location are variable in normal subjects and localization becomes even more difficult in instances of retinal disease. In normal subjects, the photoreceptor axons that make up the Henle fiber layer are cylindrical and the radial orientation of these fibers is centered on the fovea. The Henle fiber layer exhibits form birefringence, which predictably changes polarized light in scanning laser polarimetry imaging. In this study 3 graders were able to repeatably identify the fovea in 35 normal subjects using near infrared image types with differing polarization content. There was little intra-grader, inter-grader, and inter-image variability in the graded foveal position for 5 of the 6 image types examined, with accuracy sufficient for clinical purposes. This study demonstrates that scanning laser polarimetry imaging can localize the fovea by using structural properties inherent in the central macula.