Cascaded multi-scale convolutional encoder-decoders for breast mass segmentation in high-resolution mammograms.

This paper addresses breast mass segmentation from high-resolution mammograms. To cope with strong class imbalance, huge diversity of size, shape, texture and contour as well as limited receptive field, mass segmentation is achieved through a multi-scale cascade of deep convolutional encoder-decoders without any pre-detection scheme. Multi-scale information is integrated using auto-context to make long-range spatial context arising from lower scale impact training at higher resolution. The pipeline is trained end-to-end to benefit from simultaneous segmentation refinement performed at each level. It incorporates transfer learning and fine tuning from DDSM-CBIS to INbreast datasets to further improve mass delineations. The comprehensive evaluation provided for high-resolution INbreast images highlights promising model generalizability against standard encoder-decoder strategies.

[Endoscopy-guided 20-G vitrectomy in severe endophthalmitis: Report of 18 cases and literature review]. / Vitrectomie endoscopique 20Ga dans les endophtalmies sévères : série de 18 cas et revue de la littérature.

OBJECTIVE: To report the anatomical and functional outcomes after endoscopy-guided vitrectomy in a series of cases of severe endophthalmitis. Also to identify and compare the outcomes of two different modes of clinical presentation. PATIENTS AND METHODS: Retrospective case study, single center; all patients who underwent endoscopic 20Ga vitrectomy (Endo optiks E4 system) for severe endophthalmitis were included. For each case, data were recorded for: etiology, surgical indication, preoperative and postoperative visual acuity, comorbidity factors and postoperative complications, and whether any additional surgery was performed. Two groups were distinguished according to their initial mode of presentation; results were then compared in terms of complications and visual prognosis to those found in the literature. RESULTS: Eighteen patients were included, with mean age 62±19years. Severe endophthalmitis was initially obvious for 8 cases (group 1). For 10 cases, disease progression had been considered unfavorable despite adequate medical treatment (group 2). There was no statistically significant difference between the two groups (P=0.55). Endophthalmitis occurred: after intravitreal injections (4 cases), after intraocular foreign body (n=2), after cataract surgery (n=5), following a trabeculectomy (n=2), after epiretinal membrane peeling (n=3), 1 case caused by a corneal infection and 1 case of endogenous leptospirosis. Mean follow-up was 13.7months. The surgical technique was a complete 20Ga vitrectomy under endoscopic visual control. The mean operative time was 70±27minutes. The causative organism was identified in 72% of cases in vitreous humor samples, among which 77% were gram-positive organisms. The infection was controlled in 89% of cases, and these patients have recovered useful visual acuity. CONCLUSION: The value of endoscopic visualization in ophthalmology has been proven for 30 S. aureus years, but its miniaturization enhances the current enthusiasm for the use of this instrumentation. When visualization is compromised, endoscopic guided vitrectomy is very useful and may assist the surgeon in the management of these difficult cases. Our anatomical and functional outcomes are encouraging, but we must keep in mind the poor long-term prognosis of severe endophthalmitis.

[Multifocal IOLs in the high myope, 6-year follow-up]. / Implants multifocaux chez le grand myope, résultats à 6ans.

INTRODUCTION: Currently, the use of multifocal IOL's remains controversial for patients with high myopia, especially because of the risk of retinal complications and poor quality of vision. Our goal was to evaluate this retinal risk and clarify the benefits obtained in this population in terms of visual acuity. PATIENTS AND METHODS: Twenty-nine highly myopic patients (52 eyes with over 6 diopters of myopia) aged 40-69 years with early cataract by LOCSIII were selected for multifocal lens implantation, based on a healthy endothelium and retina as well as better visual acuity corrected to at least 0.5 - J2. Thirteen of them (21 eyes) had been previously implanted with a phakic IOL. The AT Lisa IOL (Zeiss©) was chosen because of the low powers available and ease of exchange. Data collection was conducted prospectively, at each visit. The main study parameters were the development of retinal complications, occurrence of PCO, patient satisfaction rate and rate of spectacle independence. RESULTS: At the end of the 6-year follow-up, we found 2 rhegmatogenous retinal detachments (3.8%) occurring at approximately 20 months and favorably treated without IOL explantation. We also found one case of macular atrophy secondary to cystoid edema. Twenty-seven uncomplicated YAG posterior capsulotomies were performed for posterior capsule opacification. Ninety-eight percent of patients reached best corrected visual acuity of at least 0.5 and 38% of at least 0.8 without correction. Finally, 85% of patients achieved spectacle independence, and all would be willing to undergo the same procedure. DISCUSSION AND CONCLUSION: Multifocal IOL implantation in the high myope provided favorable results at 6 years, in carefully selected cases, providing optimal binocular visual comfort, including near vision. However, the fragility of the highly myopic retina mandates long-term follow-up. It would be beneficial to compare results of multifocal vs. monofocal IOL implantation in terms of visual performance and safety.

[Neuro-ophthalmological assessments in the Ophthalmology Department at University Medical Center, Brest: retrospective study of 269 patients (January 2004-October 2009)]. / Bilans neuro-ophtalmologiques dans le service d'ophtalmologie du CHU de Brest : étude rétrospective sur 269 patients (janvier 2004-octobre 2009).

AIMS: To evaluate the neuro-ophthalmological assessments carried out in the ophthalmology department of the university medical center, Brest, identifying the population seen, the examinations performed, the pathologies treated and patient outcomes, so as to suggest solutions to improve quality of care. METHODOLOGY: Retrospective study over a period of more than five years, between January 1st, 2004 and October 31st, 2009. Data were collected from each patient's chart with the help of a standardized spreadsheet including epidemiological, clinical, paraclinical and treatment data. RESULTS: Analysis of the 269 charts reveals that optic neuropathies are the most frequently encountered etiologies. In addition to the standardized assessment currently used on the service, we suggest adding a specific neuro-ophthalmological clinical intake form so as to standardize and perfect the diagnostic approach. CONCLUSION: Optimization of quality of care in neuro-ophthalmology involves a multidisciplinary approach, requiring close collaboration between ophthalmologists, neurologists and radiologists. A careful, regular analysis of our practice patterns with respect to scientific advances should improve consistency and quality of care for our patients.

[Long-term results of posterior chamber phakic intraocular lens implantation for correction of high ametropia]. / Résultats à long terme de l'implantation phaque de chambre postérieure pour la correction des amétropies fortes.

PURPOSE: To assess efficacy, stability and safety of posterior chamber phakic intraocular lens implantation with STAAR Visian ICL for correction of high ametropia, with a mean follow-up of 5 years (3.5-10 years). PATIENTS AND METHODS: Ninety eyes of 53 highly ametropic patients (45 myopia, ten hyperopia and 35 with mixed astigmatism) were included in a retrospective single-surgeon study, using primarily the V4 ICL model (87 eyes). We studied pre- and postoperative refractive efficacy, endothelial cell density, crystalline lens opacification and intraocular clearances within the various compartments of the eye. RESULTS: Mean uncorrected visual acuity was 0.77 at the 12th postoperative month; 17 of 90 eyes required adjunctive photoablation for residual astigmatism. Forty-eight percent of eyes gained at least one line of best corrected visual acuity. After implantation, the decrease in endothelial cell density remained stable at 0.69%/year, and 91% of eyes showed no opacification of the crystalline lens. Mean endothelium-ICL and ICL-crystalline lens distances were 2.41 mm and 0.52 mm respectively. Overall patient satisfaction achieved was 96% at 36 months postoperatively. DISCUSSION AND CONCLUSION: These results demonstrate efficacy, stability and safety of the ICL V4 phakic IOL for the correction of high ametropia. Long-term follow-up did not show a significant increase in cataract formation in implanted eyes.

[Management of neovascular glaucoma related to the persistence after retinal detachment surgery of a circumferential peripheral retinal detachment]. / Traitement du glaucome néovasculaire lié à la persistance après chirurgie du décollement de rétine d'un décollement de rétine périphérique annulaire.

OBSERVATION: A 41-year-old male with a medical history of high myopia and several retinal detachment (RD) surgeries was referred for vitreous hemorrhage coexisting with neovascular glaucoma occurring 2 months after uncomplicated silicone oil removal on his left and single eye. The right eye had been lost to RD. The retina behind the equator was reattached on ultrasonography. We performed a washout pars plana vitrectomy on the left eye, revealing a chronic circumferential RD of the anterior retina stopped in its posterior spread by dense photocoagulation scars. We combined a retinectomy of the detached retina with an intracamerular injection of bevacizumab, resulting in complete disappearance of rubeosis and normalization of the intraocular pressure. CONCLUSIONS: The retinal ischemia related to the persistence of a chronic and circumferential RD anterior to dense photocoagulation scars after ab-interno RD surgery, whereas the rest of the retina appears reattached, is probably the causative factor of neovascular glaucoma. In the present case, the removal of RD by circumferential retinectomy combined with an intraocular injection of anti-VEGF allowed the complete and definitive regression of neovascular glaucoma.

[Treatment of circumscribed choroidal haemangiomas by photodynamic therapy: a review]. / Traitement des hémangiomes choroïdiens circonscrits par photothérapie dynamique : revue de la littérature.

Circumscribed choroidal hemangioma (CCH) is an uncommon benign vascular tumor of the choroid that is usually diagnosed when it causes a decrease in vision due to exudative retinal detachment. The classical treatments of CCH were photocoagulation and radiotherapy, which induced additional chorioretinal damage, explaining the poor visual prognosis even in adequately treated patients. It is difficult to compare these two therapeutic options, laser photocoagulation having been abandoned for many years due to the retractile retinal scars that it induced. Conventional radiotherapy and proton therapy with a total dose of 20 Gy gave and give good results but can be performed only by teams used to these types of treatment. Recently, photodynamic therapy (PDT), which allows a selective occlusion of vascular lesions without damaging overlying retinal structures, has emerged as a sound alternative for the treatment of CCH. Most of the clinicians used the standard treatment of age related macular degeneration by photodynamic therapy (TAP) study protocol with or without variations. The main variations brought to the TAP study protocol were the duration of the verteporfin infusion, and/or the increase of the laser power settings, and/or the increase of the duration of exposure, and/or the number of PDT spots (single spot or multiple spots, overlapping or not). Mid-term PDT results are very encouraging. PDT has been reported to bring about resolution of subretinal fluid and to reduce tumor thickness in almost all cases. Visual acuity was improved or stabilized in at least 80% of the cases. Several studies reported on minor local side effects following PDT, consisting of atrophy and proliferation of the retinal pigment epithelium, atrophy of the choroid, transient choroidal effusion, and mild subretinal fibrosis. Published data demonstrated that PDT is a safe and effective alternative to radiotherapy or photocoagulation as first-line therapy for CCH.

Wavelet optimization for content-based image retrieval in medical databases.

We propose in this article a content-based image retrieval (CBIR) method for diagnosis aid in medical fields. In the proposed system, images are indexed in a generic fashion, without extracting domain-specific features: a signature is built for each image from its wavelet transform. These image signatures characterize the distribution of wavelet coefficients in each subband of the decomposition. A distance measure is then defined to compare two image signatures and thus retrieve the most similar images in a database when a query image is submitted by a physician. To retrieve relevant images from a medical database, the signatures and the distance measure must be related to the medical interpretation of images. As a consequence, we introduce several degrees of freedom in the system so that it can be tuned to any pathology and image modality. In particular, we propose to adapt the wavelet basis, within the lifting scheme framework, and to use a custom decomposition scheme. Weights are also introduced between subbands. All these parameters are tuned by an optimization procedure, using the medical grading of each image in the database to define a performance measure. The system is assessed on two medical image databases: one for diabetic retinopathy follow up and one for screening mammography, as well as a general purpose database. Results are promising: a mean precision of 56.50%, 70.91% and 96.10% is achieved for these three databases, when five images are returned by the system.

[Peribulbar anesthesia: efficacy of a single injection with a limited local anesthetic volume]. / Anesthésie péribulbaire: efficacité d'une seule injection et d'un volume d'anesthésiques locaux limité.

INTRODUCTION: Cataract surgery can be performed with peribulbar anesthesia. The classical technique consists of two injections of local anesthetics. The purpose of our study was to assess peribulbar anesthesia with a single injection and a limited volume of local anesthetics. MATERIAL AND METHOD: After local ethics committee agreement and oral consent, patients scheduled for cataract surgery using peribulbar anesthesia were prospectively included. The lower temporal puncture was performed with a peribulbar needle with propofol sedation. The mixture of local anesthetics was administered with tactile control of orbital pressure. The puncture was followed by a 10-min compression of the ocular globe. Akinesia, analgesia, complications, and surgical conditions were noted. RESULTS: A total of 101 successive patients were included. We administered 1.2 mg/kg of propofol. The volume of local anesthetics administered was 5.0 +/- 0.9 ml. Ninety patients had akinesia at 10 min and 6.7% moderate chemosis. No puncture complication occurred. At the end of surgery, the pain noted by the patients was 0.4 +/- 2.1 out of 100 (range, 0-10). Surgical conditions were good for all patients. CONCLUSION: Peribulbar anesthesia performed with a single injection and a limited volume of local anesthetics allows cataract surgery in good conditions for the surgeon with very good analgesia for the patient.

[Will penetrating keratoplasty become obsolete?]. / La kératoplastie transfixiante sera-t-elle supplantée?

The development of technologies for performing lamellar cuts of the cornea constitutes a major breakthrough in corneal grafting, since it can bypass the well-identified limits of penetrative keratoplasty such as intraocular pressure elevation and graft rejection with nonreversible edema, which are major but unpredictable complications of penetrative keratoplasty. A surgical procedure that could exchange only pathologic tissue layers might be able to eliminate all these adverse events and provide faster visual recovery with better visual performance. However, certain indications for penetrative graft will certainly remain, benefiting from the considerable progress in surgical technique with the advent of femtosecond laser and the the control of immunomodulation. This article develops arguments to answer the three following questions: Why should we replace penetrative keratoplasty? Why will this procedure survive? How can we improve it?

[MALT (mucosa-associated lymphoid tissue) lymphoma of the lacrimal gland]. / Lymphome de la glande lacrymale de type MALT (Tissu Lymphoïde Annexé aux Muqueuses).

MALT lymphoma of the lacrimal gland is rare. Orbital involvement is usually located on the anterior orbit. We report the case of a 65-year-old man consulting for an eyelid tumor located on the right upper and lateral lid, which clinically recalled lacrimal gland involvement. The gland biopsy and the immunohistochemical analysis concluded in the diagnosis of B and MALT lymphoma. The assessment of the ganglion and extra-ganglion enlargement of these lymphomas is of capital importance in treatment. A multidisciplinary analysis, especially oncological, is important so that the best therapeutic plan can be adopted.

[LASIK treatment for graft astigmatism]. / Traitement LASIK de l'astigmatisme cornéen post-greffe de cornée.

OBJECTIVE: To analyze the advantages of LASIK as a treatment for postkeratoplasty residual astigmatism. PATIENTS: and METHOD: Retrospective, noncomparative, monocentric study on 14 patients with penetrative keratoplasty. Visual acuity, objective refraction, intraocular pressure, slit lamp biomicroscopy, videotopography, pachymetry, and patient satisfaction were studied before and after surgery. RESULTS: Refraction was stable 6 months after treatment in 93% (13/14) of the patients. The mean uncorrected visual acuity increased from 0.16 to 0.4. Two out of four patients (14.3%) were retreated because visual acuity did not improve after the first treatment; 35% did not need any optical correction after the intervention. The measured astigmatism showed a significant decrease, from 65% greater than 5 D before treatment to 82% under 2 D after treatment. Only two out of 14 patients (14.3%) were not satisfied. No intraocular or postoperative complications were reported in this study. CONCLUSION: LASIK seems to be an interesting option in the treatment of postkeratoplasty residual astigmatism. This study has shown its efficacy and safety in this indication. Its originality lies in the one-step procedure, with the flap and photoablation done in a single step. However, it is still dependent on the operator and most particularly the equipment (laser, microkeratome, aberrometry).

[Anterior chamber versus posterior chamber phakic IOLs]. / Implants phakes de chambre antérieure versus chambre postérieure.

At a time when some of the limitations of photoablation have been defined, such as worry concerning secondary ectasia, a renewed interest in phakic implantation has arisen. This is driven by the goal of avoiding correcting high ametropia with LASIK and is based on the development of soft foldable biomaterials. When all phakic IOLs are in front of the natural lens, two varieties of lenses can be distinguished, depending on whether it is located in the anterior or posterior chamber. The various models available in 2006 and those under current evaluation are reviewed. We do not report details of clinical studies that vary in cohort size and follow-up. The advantages and limitations are discussed for each type of phakic IOL. Adequate although not exclusive indications are deduced. There is no phakic lens that has proved to be superior to the others in terms of safety. All have the ability to provide a visual benefit with a gain in best corrected visual acuity. The difference is based on anatomical effects, requiring long-term follow-up in the evaluation of angles, lens, iris, and endothelium.

[Post-traumatic orbital emphysema: a case report]. / Emphysème orbitaire post-traumatique: à propos d'un cas.

Orbital emphysema is often associated with orbital fracture or communication with paranasal sinuses. It is usually moderate but could be the cause of optic neuropathy or central retinal artery occlusion. We report a case of massive orbital emphysema with ocular hypertony and prethrombosis of the central retinal artery. Emergency surgical decompression performed by an ophthalmologist and an otorhinolaryngologist provided complete and prompt relief. The authors emphasize the importance of preventing nose blowing after orbital trauma or surgery.

[Assessment of the Quantel Medical 20-Mhz Ultrasound Cinescan in intraocular measurements]. / Evaluation de l'échographie 20 MHz CineScan dans les mesures intra-oculaires.

BACKGROUND AND OBJECTIVE: Evaluation of the Quantel Medical 20-MHz Ultrasound Cinescan using a closed transducer in intraocular measurements and its reproducibility. PATIENTS AND METHODS: We measured sulcus-to-sulcus distance of 40 control eyes using the20-MHz Cinescan. Then we compared the sonography to the Oculus Pentacam based on the Scheimpflug principle in the measurements of anterior chamber depth, cornea-to-implant distance, and implant-to-crystallin lens distance in patients who underwent phakic implantation (56 eyes). RESULTS: With this technique, the sulcus-to-sulcus distance can be measured with a reproducibility of 86%-88% (p<0.05). The authors show that the corneal diameter is not correlated with the sulcus measurement (R=24%, p<0.05). DISCUSSION: Several techniques are used to quantify anterior segment biometry. Some of these methods, such as White-to-White, are too empirical and others, such as the Scheimpflug camera - for example the EAS-1000 (Nidek) - or high-frequency ultrasound - Ultrasound BioMicroscopy UBM P45 (Paradigm) - are too expensive. The 20-MHz Cinescan has good reproducibility and provides easier access to anterior segment biometry. CONCLUSION: The 20-MHz Cinescan appears to be an accessible technique that may become a useful tool in the refractive surgery of the phakic intraocular lens.

[Nonbiodegradable drug-sustained capsular ring for prevention of secondary cataract. Part II: In vivo evaluation]. / Anneau capsulaire non biodégradable relargant pour la prévention de la cataracte secondaire. Partie II: évaluation in vivo.

PURPOSE: The appearance of a secondary cataract constitutes the most common complication of cataract surgery since the advent of phacoemulsification. Prevention is today one of the crucial challenges of research in ophthalmology. We have developed a drug-sustained capsular ring releasing 5-fluorouracil (5-FU). This system targets the goal of combining advantageous mechanical and pharmacological properties with the ability to interfere on the epithelial cellular processes of secondary cataract. This paper presents the results of animal evaluation. MATERIAL AND METHODS: The study first developed the in vitro delivery system as a preliminary step to the animal in vivo approach. After a pilot study conducted on micro pigs, lens extraction was performed on the right eye of 22 female albino rabbits. The four study groups included: group 1 (6 animals) as a control group receiving only phacoemulsification; group 2 (6 animals) receiving phacoemulsification and the implantation of a nonsustained capsular tension ring; and group 3 (6 animals) receiving a drug-sustained ring. Group 4 (4 animals), implanted with a 5-FU-sustained ring, was reserved for staged samples of aqueous humor for kinetic determination of active agent release. RESULTS: Clinical evaluation based on biomicroscopy and histology showed a lesser reaction of secondary cataract in eyes with the ring. Compared to group 1, central posterior capsular opacification appeared significantly lower in density and surface in groups 2 and 3. No intraocular toxicity was observed. The poor sensitivity of the 5-FU detection method (high-performance chromatography) impaired pharmacokinetic evaluation. CONCLUSIONS: The decrease in secondary cataract reaction in cases of implanted capsular ring demonstrated the advantages of its mechanical effect. However, the benefit of an additive pharmacological action related to the release of 5-FU could not be proved. Nevertheless, the theoretical concept of a drug-sustained delivery system seems attractive and thus calls for evaluation of other potential modulators of cell behavior.

[Non-biodegradable drug-sustained capsular ring for prevention of secondary cataract. Part I: In vitro evaluation]. / Anneau capsulaire non biodégradable relargant pour la prévention de la cataracte secondaire. Partie I: Evaluation in vitro.

PURPOSE: The appearance of secondary cataract constitutes the most common complication of cataract surgery since the advent of phacoemulsification. Prevention is today one of the most crucial challenges of research in ophthalmology. We have developed a drug-sustained capsular ring releasing 5-fluorouracil (5-FU). This system aims to combine mechanical and pharmacological properties with the ability to interfere on the lens epithelial cellular processes of secondary cataract. This first article will report on the in vitro evaluation of this system. MATERIALS AND METHOD: Development of a hydrogel that can serve as a mechanical support and as a release of an active agent requires a comparative trial of multiple hydrophobic products providing rigidity to the ring and of hydrophilic products providing the ability to release a drug. The choice of 5-FU as a non-proliferate agent was based on its well-known pharmacological properties and its wide use in ophthalmology. Evaluation comprised adjustment of the adequate copolymer, then of the loading phase, and finally assessment of 5-FU release. The mechanical characteristics and cytocompatibility of the ring were also assessed. RESULTS: The characteristics of drug release differed depending on the water content and resulting volume of the copolymer. The pharmaceutical and mechanical testing led to selecting the HPMA-MMA combination (75:25). However, a burst effect within the first 2 hours was observed in all cases. That limit was eliminated by creating a biodegradable surface coating of Poly Lactid-co-Glycolid (PLG 50:50) that could provide a positive barrier effect against migration and a controlled continual release of 0.25 microg/h extended to 9 days. Mechanical tests of tension, compression, and traction showed the crucial influence of the ring's hydration state. The cytocompatibility study showed no evidence of cellular toxicity. DISCUSSION/CONCLUSIONS: The synthesized copolymer is able to release a constant, regular and safe rate of 5-FU, higher than CI50 over a period of 9 days for a cell proliferation phase of 3-5 days. We adjusted the ring associating the mechanical properties and the ability to release 5-FU, allowing further evaluation on animal models, the subject of the second part of this report.

[Bilateral papilledema in young women: two case reports of benign intracranial hypertension?]. / OEdème papillaire bilatéral chez la femme jeune.

We report two cases of bilateral papilledema in young women. The first patient was 15 years old and had experienced headaches and vomiting for one month, but no visual loss. Cerebral tomodensitometry results were normal, but lumbar puncture showed increased pressure and normal biology. Benign intracranial hypertension was diagnosed. Recent treatment with minocycline for acne vulgaris was the only etiology. Papilledema was totally regressed at 6 weeks, after interruption of the antibiotic treatment. A prescription of acetazolamide was added for a short period of 10 days. The second patient, aged 29 years, presented bilateral papilledema with severe visual loss, with vision limited to light perception with mydriasis of the right eye. Lumbar puncture was not indicated because of a hypophyseal microadenoma revealed on MRI investigation. No other associated abnormalities were observed, in particular, no cerebral sinus thrombosis. Corticotherapy using prednisolone for 72 hours had no clinical effect. Fast visual recovery was obtained with intravenous acetazolamide therapy and was completely resolved at 2 months. Right visual field defects persisted. Minocycline and obesity are recognized as precipitating factors in pseudotumor cerebri syndrome. The literature advocates consideration of surgical treatment by optic nerve sheath fenestration if antiedematous treatment has no effect and the eye is nearly blind.

[Motivation of candidates for refractive surgery]. / Motivation des patients candidats à une chirurgie réfractive.

PURPOSE: To determine the profile and motivations of patients who are candidates for refractive surgery. MATERIAL: and METHODS: We studied 102 patients with low myopia (less than 6 diopters) in a single-center investigation. RESULTS: Among the total population studied, the motivation for refractive surgery was essentially comfort and appearance. Fewer men wore contact lenses than women and had worn them for a shorter period of time. Those involved in sports were more often in individual sports. Contact-lens wearers were most often students or in the paramedical professions. DISCUSSION: The population interested in refractive surgery was very young. The proportion of candidates who had never worn contact lenses was surprisingly high. CONCLUSION: This analysis suggests that patients too often consider refractive surgery as an easy option.

[Modeling the eye based on simulated refractive surgery]. / Modélisation de l'oeil en vue de simulations de chirurgies réfractives.

PURPOSE: To achieve three-dimensional modelizing of the eyeball (morphological and mechanical behavior) in order to simulate the impact of various refractive surgery techniques and to study the normal and pathological states of the eye. METHOD: Rebuilding the ocular shell is based on different kinds of imaging (MRI, ultrasound) including information provided by video topography. Image data are treated using suitable numerized filters that allow automatic segmentations of ocular globus edges. Reconstruction is based on specific mathematical functions (B-splines). The mechanical behavior of a reconstructed model is simulated by solving equations of linearized elasticity with the finitude elements method. RESULTS: Numerous simulations mimmed different refractive surgical techniques and, then validated the model. In addition, simulations of various pathologies allowed us to verify certain clinical hypotheses. CONCLUSION: This work, although still experimental, demonstrates the advantages of such simulations and will allow novice physicians an easier approach to different surgical techniques and will help them understand their effect. Furthermore, it might be useful for simulation of new surgical concepts even before their in vivo evaluation.