João Pedro Marques

The role of the time step and overshooting in the modelling of PMS evolution: The case of EK Cephei

EK Cephei (HD 206821) is a unique candidate to test predictions based on stellar evolutionary models. It is a double-lined detached eclipsing binary system with accurate absolute dimensions available and a precise determination of the metallicity. Most importantly for our work, its low mass (1.12 M� ) component appears to be in the pre-main sequence (PMS) phase. We have produced detailed evolutionary models of the binary EK Cep using the CESAM stellar evolution code (Morel 1997). A χ 2 -minimisation was performed to derive the most reliable set of modelling parameters (age, αA, αB and Yi). We have found that an evolutionary age of about 26.8 Myr fits both components in the same isochrone. The positions of EK Cep A and B in the HR diagram are consistent (within the observational uncertainties) with our results. Our revised calibration shows clearly that EK Cep A is in the beginning of the main sequence, while EK Cep B is indeed a PMS star. Such a combination allows for a precise age determination of the binary, and provides a strict test of the modelling. In particular we have found that the definition of the time step in calculating the PMS evolution is crucial to reproduce the observations. A discussion of the optimal time step for calculating PMS evolution is presented. The fitting to the radii of both components is a more difficult task; although we managed to do it for EK Cep B, EK Cep A has a lower radius than our best models. We further studied the effect of the inclusion of a moderate convective overshooting; the calibration of the binary is not signifi- cantly altered, but the effect of the inclusion of overshooting can be dramatic in the approach to the main sequence of stars with masses high enough to burn hydrogen through the CNO cycle on the main sequence.

Treatment of Retinal Vein Occlusion with Ranibizumab in Clinical Practice: Longer-Term Results and Predictive Factors of Functional Outcome.

Purpose: To evaluate long-term results and predictors of efficacy in patients with macular edema due to retinal vein occlusion (RVO) treated with intravitreal ranibizumab in a clinical practice setting. Methods: The clinical records of patients with a minimum follow-up of 3 years were retrospectively analyzed. Sixteen eyes with branch RVO (BRVO) and 16 with central RVO (CRVO) were included. All patients performed cross-sectional evaluation with best-corrected visual acuity (BCVA), spectral domain optical coherence tomography and fluorescein angiography. The foveal avascular zone (FAZ) was assessed and microstructural morphology of the retina was characterized. Results: Follow- up was 42.9 ± 9.0 and 44.8 ± 8.0 months in the CRVO and BRVO groups, respectively. Patients with CRVO received on average 6.9 injections, with a final VA gain of 8.3 ± 15.0 letters (p = 0.05). BRVO eyes had on average 5.9 injections, with a final VA gain of 1.6 ± 21.0 letters (p > 0.05). The FAZ area remained stable in both groups (p > 0.05). Baseline BCVA and disruption of the retinal pigment epithelium (RPE) were predictors of final BCVA (p = 0.001 and 0.011, respectively). Conclusion: Although functional outcomes were inferior to those reported in clinical trials, ranibizumab was satisfactory in the long-term treatment of macular edema secondary to RVO and was not associated with increased macular ischemia. Final BCVA depends on baseline BCVA and RPE integrity.

A theoretical approach for the interpretation of pulsating PMS intermediate-mass stars

Context. The investigation of the pulsation properties of pre-main-sequence intermediate-mass stars is a promising tool to evaluate the intrinsic properties of these stars and to constrain current evolutionary models. Many new candidates of this class have been discovered during the last decade and very accurate data are expected from space observations obtained for example with the CoRoT satellite. Aims. In this context we aim at developing a theoretical approach for the interpretation of observed frequencies, both from the already available ground-based observations and from the future more accurate and extensive CoRoT results. Methods. To this purpose we have started a project devoted to the computations of fine and extensive grids of asteroseismic models of intermediate mass pre-main-sequence stars. The obtained frequencies are used to derive an analytical relation between the large frequency separation and the stellar luminosity and effective temperature and to develop a tool to compare theory and observations in the echelle diagram. Results. The predictive capabilities of the proposed method are verified through the application to two test stars. As a second step, we apply the procedure to two true observations from multisite campaigns and we are able to constrain their stellar parameters, in particular the mass, in spite of the small number of frequencies. Conclusions. We expect that with a significantly higher number of frequencies both the stellar mass and age could be constrained and, at the same time, the physics of the models could be tested.

Age-related macular degeneration in Portugal: prevalence and risk factors in a coastal and an inland town. The Coimbra Eye Study - Report 2.

To determine the age‐ and sex‐specific prevalence of early and late age‐related macular degeneration (AMD) in two Portuguese population‐based samples and to identify its risk factors.

Ocular Risk Factors for Exudative AMD: A Novel Semiautomated Grading System

Purpose. To evaluate the contribution of the ocular risk factors in the conversion of the fellow eye of patients with unilateral exudative AMD, using a novel semiautomated grading system. Materials and Methods. Single-center, retrospective study including 89 consecutive patients with unilateral exudative AMD and ≥3 years of followup. Baseline color fundus photographs were graded using an innovative grading software, RetmarkerAMD (Critical Health SA). Results. The follow-up period was 60.9 ± 31.3 months. The occurrence of CNV was confirmed in 42 eyes (47.2%). The cumulative incidence of CNV was 23.6% at 2 years, 33.7% at 3 years, 39.3% at 5 years, and 47.2% at 10 years, with a mean annual incidence of 12.0% (95% CI = 0.088–0.162). The absolute number of drusen in the central 1000 and 3000 μm (P < 0.05) and the absolute number of drusen ≥125 µm in the central 3000 and 6000 µm (P < 0.05) proved to be significant risk factors for CNV. Conclusion. The use of quantitative variables in the determination of the OR of developing CNV allowed the establishment of significant risk factors for neovascularization. The long follow-up period and the innovative methodology reinforce the value of our results. This trial is registered with ClinicalTrials.gov NCT00801541.

Sequential Morphological Changes in the CNV Net after Intravitreal Anti-VEGF Evaluated with OCT Angiography

Purpose: To assess and describe sequential morphological changes in the choroidal neovascularization (CNV) net using optical coherence tomography angiography (OCTA) in patients undergoing treatment with intravitreal antivascular endothelial growth factor (VEGF). Methods: Prospective cohort study. OCTA was performed sequentially: before (t0), 1 h (t1), 1 week (t2) and 1 month after the injection (t3), using Avanti RTVue XR equipped with the AngioVue® software (Optovue, Calif., USA). All images were classified by two independent graders. Results: Ten eyes of 10 patients, with a mean age of 72.4 ± 10.5 years, were included. CNV morphology was described as tree-like in 5 eyes, glomerular in 1 and fragmented in 4. A fibrovascular capsule surrounding the CNV net was found in 4 eyes and a feeder trunk was noticed in 6. No changes were observed at t1. Loss of peripheral capillaries, vessel fragmentation and decreased vessel density were evident in 8 eyes at t2. The CNV capillary density and the peripheral anastomosis increased in all of these at t3. Two eyes remained unchanged through the whole length of follow-up. Conclusions: Significant changes in the CNV net can be observable in OCTA at least 1 week after intravitreal anti-VEGF. The safety of frequent examinations may provide a method of gauging treatment effects.

Quantitative Evaluation of Visual Function 12 Months after Bilateral Implantation of a Diffractive Trifocal IOL

Purpose To quantitatively evaluate visual function 12 months after bilateral implantation of the Physiol FineVision® trifocal intraocular lens (IOL) and to compare these results with those obtained in the first postoperative month. Methods In this prospective case series, 20 eyes of 10 consecutive patients were included. Monocular and binocular, uncorrected and corrected visual acuities (distance, near, and intermediate) were measured. Metrovision® was used to test contrast sensitivity under static and dynamic conditions, both in photopic and low-mesopic settings. The same software was used for pupillometry and glare evaluation. Motion, achromatic, and chromatic contrast discrimination were tested using 2 innovative psychophysical tests. A complete ophthalmologic examination was performed preoperatively and at 1, 3, 6, and 12 months postoperatively. Psychophysical tests were performed 1 month after surgery and repeated 12 months postoperatively. Results Final distance uncorrected visual acuity (VA) was 0.00 ± 0.08 and distance corrected VA was 0.00 ± 0.05 logMAR. Distance corrected near VA was 0.00 ± 0.09 and distance corrected intermediate VA was 0.00 ± 0.06 log-MAR. Glare testing, pupillometry, contrast sensitivity, motion, and chromatic and achromatic contrast discrimination did not differ significantly between the first and last visit (p>0.05) or when compared to an age-matched control group (p>0.05). Conclusions The Physiol FineVision® trifocal IOL provided satisfactory full range of vision and quality of vision parameters 12 months after surgery. Visual acuity and psychophysical tests did not vary significantly between the first and last visit.

Efficacy and safety of postvitrectomy intravitreal triamcinolone therapy for diabetic macular edema.

Purpose After vitrectomy, diffusion and clearance rates of numerous drugs are increased, leading to a shorter intravitreal half-life. This raises doubts about the efficacy of intravitreal therapies, as retina specialists generally believe that a shorter half-life compromises the drugs’ therapeutic effect. We conducted a study to evaluate the functional and anatomical effect of intravitreal triamcinolone acetonide therapy (IVTA) in previously vitrectomized eyes with diabetic macular edema (DME). Methods In this retrospective, multicenter case series study including vitrectomized patients with DME who underwent IVTA injections, central macular thickness (CMT) measured with spectral-domain optical coherence tomography and best-corrected visual acuity (BCVA) in Early Treatment Diabetic Retinopathy Study letters were evaluated after each procedure. All relevant medical data were collected, including previous ophthalmologic treatments and comorbidities. Results Twenty vitrectomized eyes of 20 patients, mean age 58.1 years (range 40-72 years), were enrolled in the study. All patients presented DME and received at least one IVTA injection. Mean time between pars plana vitrectomy and IVTA was 12.9 ± 8.7 months. Mean pretreatment and posttreatment CMT was 438.8 ± 90.8 μm and 301.2 ± 76.2 μm, respectively, a difference that reached statistical significance (p<0.001). Mean gain in BCVA letter score was 7.83 ± 14.9 letters after treatment (p = 0.039). Mean intraocular pressure was significantly increased after IVTA (17.2 ± 1.9 mm Hg at baseline vs 21.2 ± 4.59 mm Hg after IVTA, p = 0.002). Conclusions A positive anatomical and functional effect was observed in our cohort. Our results suggest that, despite prior vitrectomy, triamcinolone remains a valid therapeutic approach for eyes with persistent DME. Further prospective randomized studies with larger patient samples are needed to validate this conclusion.

RETINAL ANGIOMATOUS PROLIFERATION: A Quantitative Analysis of the Fundoscopic Features of the Fellow Eye.

Purpose: To quantitatively analyze and compare the fundoscopic features between fellow eyes of retinal angiomatous proliferation and typical exudative age-related macular degeneration and to identify possible predictors of neovascularization. Methods: Retrospective case–control study. Seventy-nine fellow eyes of unilateral retinal angiomatous proliferation (n = 40) and typical exudative age-related macular degeneration (n = 39) were included. Fundoscopic features of the fellow eyes were assessed using digital color fundus photographs taken at the time of diagnosis of neovascularization in the first affected eye. Grading was performed by two independent graders using RetmarkerAMD, a computer-assisted grading software based on the International Classification and Grading System for age-related macular degeneration. Results: Baseline total number and area (square micrometers) of drusen in the central 1,000, 3,000, and 6,000 &mgr;m were considerably inferior in the fellow eyes of retinal angiomatous proliferation, with statistically significant differences (P < 0.05) observed in virtually every location (1,000, 3,000, and 6,000 &mgr;m). A soft drusen (≥125 &mgr;m) area >510,196 &mgr;m2 in the central 6,000 &mgr;m was associated with an increased risk of neovascularization (hazard ratio, 4.35; 95% confidence interval [1.56–12.15]; P = 0.005). Conclusion: Baseline fundoscopic features of the fellow eye differ significantly between retinal angiomatous proliferation and typical exudative age-related macular degeneration. A large area (>510,196 &mgr;m2) of soft drusen in the central 6,000 &mgr;m confers a significantly higher risk of neovascularization and should be considered as a phenotypic risk factor.

On the effect of overshooting as predicted by the modelling of the pre-main-sequence evolution of a 2 M⊙ star

We discuss the effects of convective overshooting in the pre-main-sequence (PMS) evolution of intermediate-mass stars, by analysing in detail the early evolution towards the main sequence of a 2 Mstellar model. These effects can be extremely important in the end of the PMS, when the abundances in CNO elements approach the equilibrium in the centre. We provide a possible physical explanation on why a moderate amount of overshooting produces, as the star approaches the zero-age main-sequence, an extra loop in the evolutionary tracks on the Hertzsprung-Russell diagram. An interesting feature is that there is a very well defined amount of overshooting (for a given stellar mass and chemical composition) beyond which a loop is produced. For smaller amounts of overshooting such a loop does not take place and the evolutionary tracks are similar to those found in the literature. The amount of overshooting needed to produce the loop decreases with stellar mass. We discuss the underlining physical reasons for the behaviour predicted by the evolution models and argue that it provides a crucial observational test for convective overshooting in the core of intermediate-mass stars.