Evaluation of Intraocular Pressure and Other Biomechanical Parameters to Distinguish between Subclinical Keratoconus and Healthy Corneas

Purpose: To assess the main corneal response differences between normal and subclinical keratoconus (SCKC) with a Corvis® ST device. (2) Material and Methods: We selected 183 eyes of normal patients, of a mean age of 33 ± 9 years and 16 eyes of patients with SCKC of a similar mean age. We measured best corrected visual acuity (BCVA) and corneal topography with a Pentacam HD device to select the SCKC group. Biomechanical measurements were performed using the Corvis® ST device. We carried out a non-parametric analysis of the data with SPSS software (Wilcoxon signed rank-test). (3) Results: We found statistically significant differences between the control and SCKC groups in some corneal biomechanical parameters: first and second applanation time (p = 0.05 and p = 0.02), maximum deformation amplitude (p = 0.016), highest concavity radius (p = 0.007), and second applanation length and corneal velocity ((p = 0.039 and p = 0.016). (4) Conclusions: Our results show that the use of normalised biomechanical parameters provided by noncontact tonometry, combined with a discriminant function theory, is a useful tool for detecting subclinical keratoconus.Cátedra FISABIO-Alcon-Universidad de ValenciaMedicin

Análisis de la visión del color de fumadores y fumadores consumidores moderados de alcohol

Existen indicios de que fumar y consumir alcohol puede afectar a la discriminación cromática, es por ello que en este estudio nos planteamos evaluar la visión del color con el test Farnsworth Munsell de 100 tonos (FM100h). Se incluyeron 64 observadores repartidos en tres grupos: sin consumo, con consumo de tabaco y con consumo de tabaco y moderado de alcohol. Se calcularon la puntuación TES y puntuaciones parciales para los mecanismos rojo-verde y azul-amarillo (PTESRG y PTESBY). Con estos datos se realizaron test de contraste de hipótesis, correlaciones, cálculo de componentes principales y curvas ROC. Los resultados mostraron que los observadores que fuman o fuman y beben tienen mayores valores de TES y de PTES comparado con los pacientes que no consumen, siendo el valor de TES o el cálculo de una componente principal los parámetros que mejor diagnostican los cambios de percepción de color entre consumidores y no consumidores

Prestaciones y limitaciones de Matlab para ilustrar fenómenos psicofísicos en laboratorios docentes: medida de la relación cromaticidad-luminosidad

El material (software, guiones, vídeos de explicación, cuestionarios, puesta en común de resultados…) que se recoge en el MOOC Prácticas de Psicofísica y Percepción Visual, de acceso libre, puede resultar atractivo no solo al alumnado interesado en Ciencias de la Visión, sino también para el profesorado que no domine los conocimientos informáticos necesarios para fabricar un test a demanda. A partir de este material básico puede también diseñar actividades para el aprendizaje y materiales para el aula, incluso en el curso de una clase, adaptándose a las necesidades de los alumnos. Sin olvidar los posibles errores de reproducción y la reducida resolución de color de las tarjetas gráficas de 8 bits, tras varios años de uso en los laboratorios de psicofísica, hemos visto que el sistema permite reproducir los resultados más sobresalientes de ciertos experimentos psicofísicos clave, como la medida de relación entre la cromaticidad y la luminancia

Prestaciones y limitaciones de Matlab para ilustrar fenómenos psicofísicos en laboratorios docentes: medida de umbrales cromáticos

Es posible desarrollar software en Matlab para realizar experimentos psicofísicos complejos. A pesar de factores de distorsión, ligados a errores de reproducción y a la reducida resolución de color de las tarjetas gráficas de 8 bits, tras varios años de uso en los laboratorios de psicofísica, hemos visto que el sistema permite reproducir los resultados más sobresalientes de ciertos experimentos psicofísicos clave, como la medida de las elipses de discriminación

The reference site collaborative network of the european innovation partnership on active and healthy ageing

Seventy four Reference Sites of the European Innovation Partnership on Active and Healthy Ageing (EIP on AHA) have been recognised by the European Commission in 2016 for their commitment to excellence in investing and scaling up innovative solutions for active and healthy ageing. The Reference Site Collaborative Network (RSCN) brings together the EIP on AHA Reference Sites awarded by the European Commission, and Candidate Reference Sites into a single forum. The overarching goals are to promote cooperation, share and transfer good practice and solutions in the development and scaling up of health and care strategies, policies and service delivery models, while at the same time supporting the action groups in their work. The RSCN aspires to be recognized by the EU Commission as the principal forum and authority representing all EIP on AHA Reference Sites. The RSCN will contribute to achieve the goals of the EIP on AHA by improving health and care outcomes for citizens across Europe, and the development of sustainable economic growth and the creation of jobs

Refractive changes and visual quality in patients with corneal edema after cataract surgery

Background: To assess visual quality and stabilization of refractive changes in corneal edema patients after cataract surgery, using visual acuity (VA) and contrast sensitivity measurements. Methods: Sixty-one eyes were analysed, twenty-three with and thirty-eight without corneal edema. Uncorrected and corrected distance VA (UDVA and CDVA) were determined with an EDTRS chart, the contrast sensitivity function (CSF) under photopic and mesopic illumination conditions with a CVS-1000e chart, clinical refraction, and corneal topography. Measurements were taken preoperatively, 1–2 days, 1 and 3-months after surgery. Clinical refraction was converted to vector notation (M, J0, J45) and SPSS v26.0 was used for data analysis. Results: An improvement of VA was observed through the postoperative period; changes between visits were significant for CDVA in both groups and for UDVA in the edema sample. Significant astigmatic changes ( J0,J45) between visits were not observed, but M values showed a hyperopic tendency in the edema group and a myopic shift in the control group that did not change between visits, with statistically significant differences between groups. Controls had significantly better contrast sensitivity at high spatial frequencies. Under mesopic conditions, global contrast sensitivity losses were observed in the edema group, which improved between visits in the middle frequency range. Conclusion: Corneal edema patients had a significant reduction of CDVA, and frequency-selective sensitivity losses that evidence a visual quality loss. Clinical refraction may improve visual quality, but in edema patients these losses are related to corneal changes, which did not change at three months after surgery.Medicin

Corneal Edema after Cataract Surgery

his systematic review investigates the prevalence and underlying causes of corneal edemafollowing cataract surgery employing manual phacoemulsification. A comprehensive search encom-passing databases such as PubMed, Embase, ProQuest, Cochrane Library, and Scopus was conducted,focusing on variables encompassing cataract surgery and corneal edema. Two independent reviewerssystematically extracted pertinent data from 103 articles, consisting of 62 theoretical studies and41 clinical trials. These studies delved into various aspects related to corneal edema after cataractsurgery, including endothelial cell loss, pachymetry measurements, visual performance, surgicaltechniques, supplies, medications, and assessments of endothelial and epithelial barriers. This review,encompassing an extensive analysis of 3060 records, revealed significant correlations between cornealedema and endothelial cell loss during phacoemulsification surgery. Factors such as patient age,cataract grade, and mechanical stress were identified as contributors to endothelial cell loss. Fur-thermore, pachymetry and optical coherence tomography emerged as valuable diagnostic tools forassessing corneal edema. In conclusion, this systematic review underscores the link between cornealedema and endothelial cell loss in manual phacoemulsification cataract surgery. It highlights therelevance of factors like patient demographics and diagnostic modalities. However, further researchis essential to unravel the complexities of refractive changes and the underlying mechanisms.This study was supported by the following foundations: Alcon-FOM-UVEG Cathedra, Foundation of Ophthalmology Medicine, and Universitat de València.Medicin

Spectral Transmission of the Human Corneal Layers

We have assessed the spectral transmittance of the different layers of the human cornea in the ultraviolet (UV), visible, and near-infrared (IR) spectral ranges. Seventy-four corneal sample donors were included in the study. Firstly, the corneal transmittance was measured using a spectrophotometer. Then, all samples were fixed for histopathological analysis, which allowed us to measure the thickness of each corneal layer. Finally, the absorption coefficients of the corneal layers were computed by a linear model reproducing total transmittance. The results show that corneal transmission was almost in unity at the visible and IR ranges but not at the UV range, in which the layer with higher transmission is Descemet’s membrane, whereas the stroma showed the lowest transmittance. Regarding the absorption coefficient, the most absorptive tissue was Bowman’s layer, followed by the endothelium. Variations on transmittance due to changes in the stroma, Bowman’s layer, or Descemet layer were simulated, and important transmission increases were found due to stroma and Bowman changes. To conclude, we have developed a method to measure the transmittance and thickness for each corneal layer. All corneal layers absorb UV light to a greater or lesser extent. The absorption coefficient is higher for Bowman’s layer, while the stroma is the layer with the lowest transmittance due to its thickness. Variations in stroma thickness or changes in the corneal tissue of Bowman’s layer or the endothelium layer due to some pathologies or surgeries could affect, to a greater or lesser degree, the total transmission of the cornea. Thus, obtaining accurate absorption coefficients for different layers would help us to predict and compensate these changes.Medicin

The components of adult astigmatism and their age-related changes

Purpose: To study the corneal and internal astigmatism and the age-related changes underlying the known refractive shift with-the-rule (WTR) towards against-the-rule (ATR) astigmatism. Methods: Refractive and corneal biometry data were collected for a total of 1195 healthy Caucasian subjects, recruited by ophthalmological centres across Europe. After conversion of refractive and corneal surface astigmatism to power vectors J 0 and J 45 , the total corneal and internal astigmatism were calculated. Results: Both refractive power vectors had leptokurtic distributions with a narrow peak at zero, and a broader, secondary distribution at its base, corresponding to eyes without balanced components. This may be fitted with a bigaussian function (J 0 : r² = 0.87; J 45 : r² = 0.98). Statistically significant changes in these distributions are seen with age: for refractive J 0 the narrow peak shortens progressively, while the broad peak shifts positive from to negative values, corresponding to increased astigmatism and a shift from with-the-rule towards against-the-rule. For J 45 the narrow peak shortens with age as well, while the broad peak flattens. These changes in refractive J 0 result from statistically significant negative shifts in both the corneal and internal components with age (Kruskal-Wallis, p < 0.05). Conclusion: In young participants corneal and internal astigmatism partially cancel each other out. This balance between both is gradually lost after age 50, leading to larger amounts of refractive astigmatism, as well as a reorientation of the axis. Given the small amplitude of these changes, they are unlikely to have repercussions for long term stability toric cataract or refractive surgery outcomesMedicin