Chromatic and achromatic visual fields in relation to choroidal thickness in patients with high myopia: A pilot study.

PURPOSE: To analyse the relationship between the choroidal thickness and the visual perception of patients with high myopia but without retinal damage. METHODS: All patients underwent ophthalmic evaluation including a slit lamp examination and dilated ophthalmoscopy, subjective refraction, best corrected visual acuity, axial length, optical coherence tomography, contrast sensitivity function and sensitivity of the visual pathways. RESULTS: We included eleven eyes of subjects with high myopia. There are statistical correlations between choroidal thickness and almost all the contrast sensitivity values. The sensitivity of magnocellular and koniocellular pathways is the most affected, and the homogeneity of the sensibility of the magnocellular pathway depends on the choroidal thickness; when the thickness decreases, the sensitivity impairment extends from the center to the periphery of the visual field. CONCLUSIONS: Patients with high myopia without any fundus changes have visual impairments. We have found that choroidal thickness correlates with perceptual parameters such as contrast sensitivity or mean defect and pattern standard deviation of the visual fields of some visual pathways. Our study shows that the magnocellular and koniocellular pathways are the most affected, so that these patients have impairment in motion perception and blue-yellow contrast perception.

Abacavir usage patterns and hypersensitivity reactions in the EuroSIDA cohort.

OBJECTIVES: Five to eight per cent of HIV-positive individuals initiating abacavir (ABC) experience potentially fatal hypersensitivity reactions (HSRs). We sought to describe the proportion of individuals initiating ABC and to describe the incidence and factors associated with HSR among those prescribed ABC. METHODS: We calculated the proportion of EuroSIDA individuals receiving ABC-based combination antiretroviral therapy (cART) among those receiving cART after 1 January 2009. Poisson regression was used to identify demographic, and current clinical and laboratory factors associated with ABC utilization and discontinuation. RESULTS: Between 2009 and 2016, of 10 076 individuals receiving cART, 3472 (34%) had ever received ABC-based cART. Temporal trends of ABC utilization were also heterogeneous, with 28% using ABC in 2009, dropping to 26% in 2010 and increasing to 31% in 2016, and varied across regions and over time. Poisson models showed lower ABC utilization in older individuals, and in those with higher CD4 cell counts, higher cART lines, and prior AIDS. Higher ABC utilization was associated with higher HIV RNA and poor renal function, and was more common in Central-East and Eastern Europe and lowest during 2014. During 779 person-years of follow-up (PYFU) in 2139 individuals starting ABC after 1 January 2009, 113 discontinued ABC within 6 weeks of initiation for any reason [incidence rate (IR) 14.5 (95% confidence interval (CI) 12.1, 17.5) per 100 PYFU], 13 because of reported HSR [IR 0.3 (95% CI 0.1, 1.0) per 100 PYFU] and 35 because of reported HSR/any toxicity [IR 4.5 (95% CI 3.2, 6.3) per 100 PYFU]. There were no factors significantly associated with ABC discontinuation because of reported HSR/any toxicity. CONCLUSIONS: ABC remains commonly used across Europe and the incidence of discontinuation because of reported HSR was low in our study population.

Photoprotection and photoreception of intraocular lenses under xenon and white LED illumination.

OBJECTIVE: To analyze the photoprotection and phototransmission that various intraocular lenses (IOLs) provide under the illumination of a xenon (Xe) lamp and white LEDs (light emitting diode). METHODS: The spectral transmission curves of six representative IOLs were measured using a Perkin-Elmer Lambda 35 UV/VIS spectrometer. Various filtering simulations were performed using a Xe lamp and white LEDs. The spectral emissions of these lamps were measured with an ILT-950 spectroradiometer. RESULTS: The IOLs analyzed primarily show transmission of nearly 100% in the visible spectrum. In the ultraviolet (UV) region, the filters incorporated in the various IOLs did not filter equally, and some of them let an appreciable amount of UV through. The Xe lamp presented a strong emission of ultraviolet A (UVA), and its emission under 300nm was not negligible. The white LED did not present an appreciable emission under 380nm. CONCLUSIONS: The cut-off wavelength of most filters is between 380 and 400nm (Physiol Hydriol60C(®), IOLTECH E4T(®), Alcon SA60AT(®), Alcon IQ SN60WF(®)), so that their UV protection is very effective. Nonetheless, the IOL OPHTEC Oculaid(®) contains a filter that, when a Xe lamp is used, lets through up to 20% for 350nm and up to 15% for 300nm, which at this point is ultraviolet B (UVB). The OPHTEC(®) Artisan IOL has a transmission peak below 300nm, which must be taken into account under Xe illumination. White LEDs do not emit energy below 380nm, so no special protection is required in the UV region.

Manejo diagnóstico del cólico renal / Diagnostic management of renal colic

El cólico renal es un motivo frecuente de consulta en los Servicios de Urgencias y la imagen diagnóstica se ha convertido en una herramienta fundamental del diagnóstico y manejo clínico. La ecografía y, fundamentalmente, la tomografía computarizada sin contraste permiten diagnosticarlo con un rendimiento elevado. El manejo radiológico va a depender de la disponibilidad del centro y de las características de la población. Es imprescindible usar técnicas de baja dosis de radiación en la tomografía computarizada y técnicas alternativas como la ecografía en embarazadas y niños. En este artículo hacemos una revisión epidemiológica, clínica, radiológica y del manejo clínico de la litiasis ureteral (AU)

Renal colic is a common reason for presentation to emergency departments, and imaging has become fundamental for the diagnosis and clinical management of this condition. Ultrasonography and particularly noncontrast computed tomography have good diagnostic performance in diagnosing renal colic. Radiologic management will depend on the tools available at the center and on the characteristics of the patient. It is essential to use computed tomography techniques that minimize radiation and to use alternatives like ultrasonography in pregnant patients and children. In this article, we review the epidemiology, clinical and radiologic presentations, and clinical management of ureteral lithiasis (AU)

Diagnostic management of renal colic.

Renal colic is a common reason for presentation to emergency departments, and imaging has become fundamental for the diagnosis and clinical management of this condition. Ultrasonography and particularly noncontrast computed tomography have good diagnostic performance in diagnosing renal colic. Radiologic management will depend on the tools available at the center and on the characteristics of the patient. It is essential to use computed tomography techniques that minimize radiation and to use alternatives like ultrasonography in pregnant patients and children. In this article, we review the epidemiology, clinical and radiologic presentations, and clinical management of ureteral lithiasis.

Spectral transmission of the pig lens: effect of ultraviolet A+B radiation.

OBJECTIVE: To determine the spectral transmission curve of the crystalline lens of the pig. To analyse how this curve changes when the crystalline lens is irradiated with ultraviolet A+B radiation similar to that of the sun. To compare these results with literature data from the human crystalline lens. PROCEDURES: We used crystalline lenses of the common pig from a slaughterhouse, i.e. genetically similar pigs, fed with the same diet, and slaughtered at six months old. Spectral transmission was measured with a Perkin-Elmer Lambda 35 UV/VIS spectrometer. The lenses were irradiated using an Asahi Spectra Lax-C100 ultraviolet source, which made it possible to select the spectral emission band as well as the intensity and exposure time. RESULTS: The pig lens transmits all the visible spectrum (95%) and lets part of the ultraviolet A through (15%). Exposure to acute UV (A+B) irradiation causes a decrease in its transmission as the intensity or exposure time increases: this decrease is considerable in the UV region. CONCLUSIONS: We were able to determine the mean spectral transmission curve of the pig lens. It appears to be similar to that of the human lens in the visible spectrum, but different in the ultraviolet. Pig lens transmission is reduced by UV (A+B) irradiation and its transmission in the UV region can even disappear as the intensity or exposure time increases. An adequate exposure intensity and time of UV (A+B) radiation always causes an anterior subcapsular cataract (ASC).

Ultraviolet radiation at Mediterranean latitudes and protection efficacy of intraocular lenses.

PURPOSE: After determining the mean intensity of ultraviolet radiation to which the human eye is exposed at Mediterranean latitudes, this data is used to evaluate the efficacy of the ultraviolet filters incorporated into various intraocular lenses. METHODS: Ultraviolet radiation measured at Mediterranean latitudes was used as a reference for the theoretical calculation of the amount of radiation to which the human eye is exposed. The spectral transmission curve from 290 to 380 nm was measured for 10 IOLs using a UV/VIS Perkins-Elmer Lambda 800 spectrometer. RESULTS: At Mediterranean latitudes, at sea level, with a mean annual solar irradiation of 50 j/cm(2), the human eye receives a quantity of UVA and UVB that is lower than the threshold toxic dose for the rabbit crystalline lens (93 j/cm(2) for UVA and 6.45 j/cm(2) for UVB). However, at higher altitudes and with albedo approaching 0.9 (fresh snow), the amount of radiation increases, with duration of exposure potentially playing a significant role. The UV filters incorporated into the IOLs studied are, in general, protective against such levels of radiation. CONCLUSION: At Mediterranean latitudes, at sea level, the amount of UV radiation to which our eyes are exposed is insufficient to damage the crystalline lens; however, at higher altitudes, the risk of such damage exists. UV filters incorporated into intraocular lenses are generally effective, since they filter all radiation with wavelengths under 380 nm.

Influence of the luminance level on visual performance with a disposable soft cosmetic tinted contact lens.

The purpose of the present work was to study the effect on visual performance of wearing disposable soft tinted contact lenses for cosmetic purposes. Parameters such as contrast sensitivity (Vistech 6000), colour vision (Farnsworth-Munsell 100-Hue colour test), visual fields (static Goldmann perimetry) and subjective vision (what the wearer feels while wearing the lenses) were studied under different illumination levels in order to check for possible vision losses while wearing these contact lenses at low illumination levels. Sixteen emmetropic subjects were fitted consecutively with seven pairs of different colour lenses (Optima Colors lenses by Bausch & Lomb), and the experimental parameters were measured under four different illumination levels (60, 6, 1, and 0.1 cd/m2; but 15 and 0.3 cd/m2 for the static perimetry) The results obtained showed no statistically significant differences in visual performance between wearing the lenses and not wearing them (p > 0.01), except for the static perimetry, in which statistically significant differences (p < 0.01) occur at eccentricities greater than 30 degrees.

Perceptual feedback in multigrid motion estimation using an improved DCT quantization.

In this paper, a multigrid motion compensation video coder based on the current human visual system (HVS) contrast discrimination models is proposed. A novel procedure for the encoding of the prediction errors has been used. This procedure restricts the maximum perceptual distortion in each transform coefficient. This subjective redundancy removal procedure includes the amplitude nonlinearities and some temporal features of human perception. A perceptually weighted control of the adaptive motion estimation algorithm has also been derived from this model. Perceptual feedback in motion estimation ensures a perceptual balance between the motion estimation effort and the redundancy removal process. The results show that this feedback induces a scale-dependent refinement strategy that gives rise to more robust and meaningful motion estimation, which may facilitate higher level sequence interpretation. Perceptually meaningful distortion measures and the reconstructed frames show the subjective improvements of the proposed scheme versus an H.263 scheme with unweighted motion estimation and MPEG-like quantization.

Optic nerve aspergillosis: report of a case diagnosed by fine-needle aspiration biopsy.

The aim of this study was to describe the fine-needle aspiration biopsy (FNAB) procedure in patient with a optic nerve lesion. A case of optic nerve and brain aspergillosis, an infrequent condition that can mimic tumor or tumor-like lesions, is reported. The patient was studied by CT and MRI and definite diagnosis was established by means of an ultrasound-guided FNAB. Specimen preparation revealed the presence of multiple hyphae of Aspergillus fumigatus in the optic nerve lesion. The FNAB procedure is a safe and reliable diagnostic method for suspected intraorbitary tumors and tumor-like conditions especially when other less-invasive modalities have failed to establish the diagnosis and when cytologic confirmation is needed to implement aggressive therapy.

Characterization of the visual performance with soft daily wear disposable contact lenses.

We investigate the visual performance associated with adaptation to a daily wear soft contact lens on the human eye. For this purpose, we used four parameters, one of which was an objective parameter, while the rest were subjective parameters. The objective parameter was a single quality parameter, a Merit function (Mf) derived from the modulation transfer function (MTF) of the overall [eye + contact lens] system The subjective parameters were the visual acuity (VA), the contrast sensitivity function (CSF) and the standard adaptation criterion of Terry et al. (1993). The normality criterion for the MTF was determined by evaluating the fluctuations of the Mf over a day in five emmetropic observers. Fluctuations with no statistically significant differences in the merit function (p > 0.05) and their standard deviation (8%) defined our standard criterion. The CSF and the VA were similarly measured (for emmetropic observers). The results obtained with emmetropic observers allowed us to establish a standard criterion for the evaluation parameters we propose. When this criterion is applied to daily soft wear disposable contact lenses, their performance proves to be good, since both the objective (MTF) and the subjective parameters (CSF, VA, adaptation criterion) always lie within the range defined by our criterion.

Spontaneous enterourachocutaneous fistula in Crohn's disease: sonographic diagnosis.

Spontaneous abdominal wall fistulas are rare in Crohn's disease. We report a case of enterourachocutaneous fistula in a woman with Crohn's disease and present the sonographic, computed tomographic, and sinographic findings.

Implementations of a novel algorithm for colour constancy.

In agreement with the principles of the relativistic model proposed by Creutzfeldt et al., with the photometric rule (lightness anchoring rule) and with the influence of simultaneous contrast in the appearance of a visual scene, we propose a first-stage mechanism yielding substantial colour constancy. We have defined a set of first-stage colour descriptors, and to test their utility, we have performed a simulation using a Machine Vision System (MVS). The statistical stability of the descriptors for Munsell samples under different illuminants is good.

[Contribution of hepatic scintigraphy with Tc99m blood cells to the imaging diagnosis of cavernous hemangioma. Results in 48 patients]. / Contribución de la gammagrafía hepática con hematíes Tc99m al diagnóstico por imagen del hemangioma cavernoso. Resultados en 48 pacientes.

Cavernous hemangiomas are the most common benign tumours of the liver, being the liver the most frequent organ affected by this lesions. We report 48 patients who underwent 99mTc-red blood cell (RBC) scintigraphy, after ultrasound or tomographic appearance of cavernous hemangioma. Scintigraphy findings in 29 of 48 patients (60.4%) were typical of cavernous hemangioma, hemangioma-positives, after scintigraphy (all true-positives). On clinical, ultrasound and in one case after surgery (exploratory laparotomy) the follow up was positive for hemangioma. Specificity of 100%. In the remaining 19 patients (39.6%) where hemangioma-negative lesions, 17 of 19 where true negatives and the remaining 2 where angiomas false-negatives, both of them were small lesions. The sensitivity for hemangiomas was 89.4%. To conclude with we would like to enhance the high specificity and sensitivity of 99mTc-red blood cell scintigraphy on the diagnosis of cavernous hepatic hemangioma (CHH). We highlight the utility of this specific imaging technique in the final diagnosis of CHH not requiring other invasive diagnosis tests, such as laparoscopy that in our study proved to be unnecessary.

Human contrast sensitivity in coherent Maxwellian view: effect of coherent noise and comparison with speckle.

Lasers have been used in vision for measuring the neural contrast sensitivity function (CSF) by forming interference fringes on the retina. We distinguish among three kinds of illumination with lasers: incoherent (without noise), Maxwellian or coherent (with coherent noise), and diffuse coherent (with speckle). The three have different characteristics and different CSF's. A coherent imaging system is designed to measure the CSF with fully coherent illumination. This is the CSF of the whole visual system, although it is measured with gratings imaged on the retina. It therefore differs from the neural CSF's measured by other authors with partially coherent illumination. However, the neural CSF's are also obtained in this study with and without noise. The effects of coherent noise and speckle on both the visual system and neural sensitivities are studied and compared. Coherent noise differs from speckle in the following ways: (1) It behaves as a high-pass filter, reducing sensitivity in the low-spatial-frequency range, whereas speckle is a low-pass filter; (2) quantitatively, coherent noise reduces neural sensitivity by a factor k(m) with a maximum value between 4 and 6, whereas speckle reduces neural sensitivity by a factor ks with a maximum value of approximately 25 (1.4 log units) for a 3-mm pupil and up to 35 (1.55 log units) for a 1-mm pupil; (3) the masking effect of the coherent noise is affected by changes in luminance but not by changes in pupil diameter; however, the pupil size is the main parameter affecting the masking effect of the speckle.