[Virtual simulation for learning cataract surgery]. / Simulation virtuelle pour l'apprentissage de la chirurgie de cataracte.

INTRODUCTION: The training in phacoemulsification cataract surgery in our context requires a long learning curve for a novice surgeon starting from the observation period to the realization of the different operating stages being supervised by a senior surgeon, all under stressful conditions. Topical or locoregional anesthesia limits the communication in the operating room between the novice surgeon and his mentor; thus, increasing the risk of having more operative complications. To reduce the teaching time of cataract surgery, our department has introduced virtual simulator trainings for phacoemulsification. PURPOSE OF THE STUDY: To assess the impact of surgical simulator training on residents' performances. MATERIAL AND METHODS: We conducted a prospective comparative study in our department in partnership with a private ophthalmology clinic where the simulator is installed. Twelve residents were included in this study, six of them were randomly selected to participate in the phacoemulsification surgical simulator training while the others never used the simulator. The training lasted 30 hours in total. No residents had previous training in phacoemulsification. The parameters studied were: the operating time, the achievement of a circular capsulorhexis of 5-6mm in diameter and well centered, the number of capsular breaks with or without an anterior vitrectomy and finally the accumulated dissipated energy (EDC). The cataract surgery was performed on an Alcon Centurion platform. RESULTS: In the operating room, each resident operated 25 cataracts; we compared the two user groups including the simulator and non simulator user and we noticed a statistically significant difference (P<0.05) in terms of average operating time respectively 20 minutes and 37 minutes. Regarding the realization of capsulorhexis; 22 cases of rhexis wandering and 12 poorly centred rhexis on 150 operated cataracts were identified (22.7%) in the group of residents who received no simulator training versus 10 cases in the simulator user group (6.7%). The cumulative dissipated energy (EDC) was significantly lower in the simulator user group (8.1 versus 18.7). The same is true for the rate of posterior capsular rupture, which is higher in the non-user group of simulator 37 cases (24.6%) versus 10 cases (8%) in the second group. DISCUSSION: Ophthalmic surgery has benefited from the introduction of endo-ocular surgical simulation tools through simulators of vitreoretinal surgery and phacoemulsification; whose main role is primarily pedagogical because a simulator allows young residents to acquire dexterity and autonomy over a shortened period of time in addition to minimizing the risk of complications. CONCLUSION: Initial learning of phacoemulsification cataract surgery should be an integral part of the virtual simulator program before moving to the real conditions of the operating room as it allows for better operative performance with a minimal complication rate.

Flocculation monitoring of wastewater by using impedance spectroscopy.

The aim of the present work is to monitor the flocculation process using the analysis of the electric and dielectric properties. Therefore the dielectric and electrical characteristics of wastewater with different cationic polymer concentrations were investigated via the impedance spectroscopy (IS) method. Impedance measurements were carried at different concentration of cationic polymer in the frequency range from 0.1 Hz to 100 kHz. The analysis of complex permittivity spectra was described by the superposition of a power law at a low frequency related to the diffusion process and Cole-Cole relaxation behavior at high frequency. Moreover, an equivalent circuit model was developed in order to analyze the experimental data and to further investigate both processes. The variation of the parameters extracted from the equivalent circuit with the increase of cationic polymer concentrations has shown a net transition at 10 mg/l. This behavior could reflect the flocculation of dispersed particles at 10 mg/l. The findings in this work could draw new attention toward the monitoring of the coagulation-flocculation process using impedance spectroscopy and could be extended to other kinds.

[Orbital decompression in exophthalmos due to thyroid disease. Report of 69 cases]. / Décompression orbitaire au cours de l'exophtalmie dysthyroïdienne. A propos de 69 cas.

Dysthyroid exophthalmos is due to mismatching of the orbit and its contents, essentially due to muscle enlargement, and, to a lesser degree, fat volumetric changes. Surgical treatment is designed to expand the orbital volume by bone removal or to reduce orbital contents by fat removal, or a combination of the two techniques. Our series consisted of 69 patients who underwent orbital decompression for proptosis, with osteotomy (12 cases) or associated with fat removal (57 cases). We obtained good results for all cases, and did not encounter any complications. Several factors now appear to play a role in the choice of surgical technique, particularly the preoperative radiologic (CT) examination which determines the muscular and fat involvement, wall orbital changes and appearance of the sinuses. Orbital fat removal seems to be useful in proptosis reduction in those cases in which fat is more involved and easy to remove. Anthral ethmoidal decompression is the best technique in the case of dysthyroid optic neuropathy.