Subfoveal perfluorocarbon liquid. Removal after three months. / Perfluorocarbono líquido subfoveal. Extracción después de 3 meses.

CLINICAL CASE: A case of surgical removal of a subfoveal perfluorocarbon liquid (PFCL) bubble that remained trapped inside the subretinal space. PFCL bubble extraction was performed by performing a therapeutic and vacuum PFCL bubble macular retinal detachment. DISCUSSION: The elapsed time before subfoveal PFCL extraction seems to influence the visual result. There are other factors which could influence the final visual acuity significantly, nevertheless it is possible to achieve useful vision, as long as the fovea is not damaged and iatrogenic injuries are avoided during PFCL bubble extraction.

Electrostatic heteroaggregation regimes in colloidal suspensions.

Despite of their importance for many industrial applications and the understanding of natural phenomena, heteroaggregation processes have not been in the focus of attention of the scientific community until quite recently. Still nowadays, their tremendously complex nature turns a detailed experimental and theoretical treatment of these processes into a difficult task. Hence, we have limited the scope of this review to electrostatic heteroaggregation arising in symmetric two-component systems, i.e., those with the same concentration of cationic and anionic particles. The short and long-time aggregation kinetics will be addressed not only from an experimental but also from a theoretical and simulation point of view at almost six orders of magnitude of electrolyte concentration. The different aggregation regimes will be identified and described in detail.

Stability of binary colloids: kinetic and structural aspects of heteroaggregation processes.

This review reports on recent advances in our knowledge about the stability of binary colloids. We focus not only on experimental results but also discuss theoretical and simulation studies regarding kinetic and structural aspects of heteroaggregation processes arising in such systems. In the first part of this work, heteroaggregation of oppositely charged particles is reviewed. When the interactions are short ranged, binary diffusion-limited cluster-cluster aggregation takes place. In this case, the short time behavior of the system follows the Hogg, Healy and Fuerstenau (HHF) theory. At long times, however, stable aggregates may form and remain in the system. Furthermore, cluster discrimination is observed, clusters that differ only by one constituent particle were found to behave quite differently. When the range of the interactions is increased, the latter effects become more pronounced. The fractal dimension of heteroaggregates is, in general, smaller than the values reported for fast and slow homoaggregation processes. In some cases, even values close to unity were obtained. This means that heteroaggregates have an open branched structure that may approach a chain-like morphology. In the second part of this work, we briefly discuss similar effects arising in heteroaggregation phenomena due to differences in particle size and chemical composition. The third part of this review tackles recent developments in the field of equilibrium phase diagrams of binary colloids. In the last section, the relatively small number of papers about heteroaggregation processes in two-dimensional systems is also discussed.

Formation and structure of stable aggregates in binary diffusion-limited cluster-cluster aggregation processes.

Binary diffusion-limited cluster-cluster aggregation processes are studied as a function of the relative concentration of the two species. Both, short and long time behaviors are investigated by means of three-dimensional off-lattice Brownian Dynamics simulations. At short aggregation times, the validity of the Hogg-Healy-Fuerstenau approximation is shown. At long times, a single large cluster containing all initial particles is found to be formed when the relative concentration of the minority particles lies above a critical value. Below that value, stable aggregates remain in the system. These stable aggregates are composed by a few minority particles that are highly covered by majority ones. Our off-lattice simulations reveal a value of approximately 0.15 for the critical relative concentration. A qualitative explanation scheme for the formation and growth of the stable aggregates is developed. The simulations also explain the phenomenon of monomer discrimination that was observed recently in single cluster light scattering experiments.

Cluster discrimination in electrostatic heteroaggregation processes.

Electrostatic heteroaggregation processes arising in 1:1 mixtures of oppositely charged microspheres at low and very low electrolyte concentrations were investigated by means of single-cluster light scattering. Cluster discrimination, i.e., the fact that clusters differing by only one constituent particle behave quite differently, was found for monomers and dimers. This effect was recently predicted by Brownian dynamic simulations but, to the best of our knowledge, not yet confirmed by experiments. The experimental data were confronted with the simulations and a good qualitative and quantitative agreement was obtained. The origin of the cluster discrimination phenomenon could be related to the range of the attractive electrostatic interactions.

Acute anterior ischemic optic neuropathy in birdshot retinochoroidopathy.

Visual loss in birdshot retinochoroidopathy has been reported to be produced by cystoid macular edema, optic atrophy, epiretinal macular membranes and subretinal neovascularization. We present a patient with this syndrome in whom the visual loss was due to an acute anterior ischemic optic neuropathy. The possible common pathogenesis of both diseases is discussed.

[Bilateral juxtapapillary subretinal neovascularization in a case of pseudotumor cerebri]. / Néo-vascularisation sous-rétinienne juxtapapillaire bilatérale dans un cas de pseudotumor cerebri.

A 39 year old woman presented a sudden loss of vision in her right eye due to a sero-hemorrhagic retinal detachment associated to bilateral papilledema. A bilateral juxtapapillary subretinal neovascularization was observed on fluorescein angiography. Neurologic examination was normal except for intracranial pressure that was 22 mmHg. Lowering of the intracranial pressure with acetazolamide and prednisone resulted in a rapid improvement of visual acuity, with resorption of the hemorrhages and involution of the subretinal membranes.