[Distribution of corneal thickness in the Tunisian population: Study by anterior segment optical coherence tomography]. / Distribution de l'épaisseur cornéenne centrale dans la population tunisienne : étude par tomographie en cohérence optique du segment antérieur.

GOALS: To describe the distribution of the central corneal thickness (CCT) in the Tunisian population. METHODS: A prospective descriptive study was performed in 201 right eyes of 201 randomly selected healthy Tunisian subjects without glaucoma. We measured the spherical error by autorefraction, the axial length using A-scan ultrasound biometry and the central corneal thickness using anterior segment optical coherence tomography (DRI TRITON OCT). RESULTS: We examined 201 eyes. The mean age was 47±13.5 years (18 to 77 years). The M/F sex ratio was at 0.46 (137 women and 64 men). The mean CCT was 508,1µm (standard deviation 31,5µm) and ranged from 440 to 600µm. In our population 43.8% had a CCT less than 500µm, and 89.1% had a CCT less than 550µm. No statistically significant correlation was observed between CCT and age, sex, spherical error or axial length. CONCLUSION: Central corneal thickness in the Caucasian Tunisian population is less than CCT in the European and Asian populations. CCT is independent of age, sex, spherical error or axial length. These results must be confirmed by larger multicentric studies.

[Anatomo-functional study in branch retinal vein occlusion using Swept Source Optical Coherence Tomography Angiography]. / Occlusion de branche veineuse rétinienne : analyse anatomo-fonctionnelle par Swept Source Optical Coherence Tomography Angiographie (OCT-Angiographie).

INTRODUCTION: The purpose of our study was to describe the microvascular abnormalities on OCT-angiography in eyes with branch retinal vein occlusion (BRVO), to measure the surface of the foveal avascular zone (FAZ) and the capillary density, and to establish anatomic-functional correlations. METHODS: We conducted an observational prospective study in the ophthalmology department of Habib Thameur Hospital in Tunis, which included 17 eyes of patients with unilateral BRVO. We studied the microvascular abnormalities and areas of capillary non-perfusion in the deep and superficial capillary plexuses (DCP, SCP). The area of the FAZ was measured in the SCP and correlated to visual acuity. The foveal and parafoveal capillary density was measured with flow quantification software. RESULTS: The mean patient age was 57.94 ±18.04 years. Male:female ratio was approximately 1. Fourteen eyes (82.4%) showed cystoid macular edema which was significantly correlated to poor visual acuity (P=0.02). Vascular congestion was present in 12 eyes (70.60%) in the DCP and 8 eyes (47.1%) in the SCP. Intraretinal loops were found in 5 eyes (29.4%) in the DCP and 8 eyes (47.1%) in the SCP. Thirteen eyes (76.5%) exhibited vascular tortuosity in the DCP, and 14 eyes (82.4%) in the SCP. Areas of capillary non-perfusion were observed in 12 eyes (70.60%). The mean area of the FAZ was 617.53±525.75µ in eyes with BRVO. Enlargement of the FAZ was correlated to visual loss (P=0.01). Mean foveal capillary density was 15.49% (±5.18%), and mean peripheral capillary density was 44% (±4.75%). There was no correlation between vascular density and visual acuity in our series. CONCLUSIONS: OCT-angiography is part of the current diagnostic workup for RVO. It has a relevant role in establishing a prognosis by studying the area of the FAZ and the capillary density.

[Bilateral pseudotumoral proptosis as presenting sign of orbital hyper-IgG4-related disease]. / Exophtalmie bilatérale pseudo-tumorale révélant un syndrome hyper-IgG4 orbitaire.

INTRODUCTION: Hyper-IgG4 syndrome is a rare cause of bilateral proptosis. It must always be considered after ruling out orbital lymphoma. CASE REPORT: We report a case of progressive bilateral proptosis for 4 years in a 34-year-old man. Orbital MRI showed an infiltrative process extending to the orbital fat, extraocular muscles and lacrimal glands. Lacrimal gland biopsy with immunohistochemical study showed a lymphoplasmocytic infiltrate rich in IgG4 and fibrosis. The diagnosis of orbital hyper-IgG4 syndrome was suggested. The patient responded well to systemic steroid treatment. DISCUSSION: Orbital hyper-IgG4 syndrome manifests most often as pseudo-tumoral bilateral proptosis. Elevated IgG4 levels are neither sensitive nor specific. Biopsy with immunohistochemical study is the key to diagnosis. Systemic steroid treatment is the gold standard, but recurrences may occur.

Mullins effect in polyethylene and its dependency on crystal content: A network alteration model.

This contribution is focused on the Mullins effect in polyethylene. An ultra-low-density polyethylene with 0.15 crystal content, a low-density polyethylene with 0.3 crystal content and a high-density polyethylene with 0.72 crystal content are subjected to cyclic stretching over a large strain range. Experimental observations are first reported to examine how the crystal content influences the Mullins effect in polyethylene. It is found that the cyclic stretching is characterized by a stress-softening, a hysteresis and a residual strain, whose amounts depends on the crystal content and the applied strain. A unified viscohyperelastic-viscoelastic-viscoplastic constitutive model is proposed to capture the polyethylene response over a large strain range and its crystal-dependency. The macro-scale polyethylene response is decomposed into two physically distinct sources, a viscoelastic-viscoplastic intermolecular part and a viscohyperelastic network part. The local inelastic deformations of the rubbery amorphous and crystalline phases are considered by means of a micromechanical treatment using the volume fraction concept. Experimentally-based material kinetics are designed by considering the Mullins effect crystal-dependency and are introduced into the constitutive equations to capture the experimental observations. It is shown that the model is able to accurately reproduce the Mullins effect in polyethylene over a large strain range. The inherent deformation mechanisms are finally presented guided by the proposed constitutive model.

[Angioid streaks complicated by choroidal neovascularization secondary to pseudoxanthoma elasticum: diagnosis and treatment. Case report]. / Stries angioïdes compliquées de néovaisseaux choroïdiens révélant un pseudoxanthome élastique : diagnostic et stratégie thérapeutique. À propos d'un cas.

Angioid streaks represent linear breaks in Bruch's membrane secondary to a change in the elastic layer. They are often associated with pseudoxanthoma elasticum. We report the case of a 36-year-old man with no prior history who was seen for a macular problem in the left eye, eventually involving the right eye after 3 months. He was diagnosed with pseudoxanthoma elasticum, associated with angioid streaks, complicated by choroidal neovascularization in both eyes. He was treated with intravitreal ranibizumab injections (0.5 mg/0.05 mL). His course in the right eye was remarkable for stable improvement at 3 months after the final injection. In the left eye, after initial improvement, recurrence was noted 2.5 months after injection, with subfoveal progression of the choroidal neovascularisation, unresponsive to a fourth ranibizumab injection. Angioid streaks represent a degenerative retinal pathology of elastic tissue with the potential for ingrowth of choroidal neovascularization. Various therapeutic approaches such as photodynamic therapy or laser photocoagulation have been proposed, with variable and sometimes limited results. Intravitreal ranibizumab injections currently remain the best treatment and should be studied with a longer-term, larger series.

[Creation and report of the Tunisian Fanconi Anemia Registry (TFAR)]. / Création et rapport du registre tunisien de l'anémie de Fanconi (TFAR).

INTRODUCTION: Fanconi anemia (FA) is a genetically and phenotypically heterogeneous inherited disease. Many groups have established FA registries. In Tunisia, in collaboration with the Tunisian Fanconi Anemia Study Group (TFASG), we set up the Tunisian Fanconi Anemia Registry (TFAR). PATIENTS AND METHODS: We contacted all hematology and pediatrics departments to include their FA patients diagnosed between January 1983 and December 2008. The registry is available on the TFASG web site (www.fanconi-tunisie.net). RESULTS: Sorting the files brought out 142 patients belonging to 118 families. The mean age at diagnosis was 11 years. There was consanguinity in 86%, malformative syndrome in 91%, and pancytopenia at diagnosis in 69%. Of 28 patients, 95% belonged to the FANCA group. Androgen treatment was given in 109 cases and genoidentical bone marrow transplantation (BMT) in 27 patients. The diagnosis of a myelodysplastic syndrome was retained in 4%, acute leukemia in 6%, and a solid tumor in 2%. The median overall survival time in all patients is 17 years 5 months; it is significantly better in patients having received allografts (p=0.01). CONCLUSION: FA seems frequent in Tunisia, which is in part explained by the high consanguinity and endogamy in this country. Hematologic impairment is still the most frequent revealing circumstance of the disease. It is often severe or moderate and requires androgen treatment or bone marrow transplantation. BMT should be proposed to all patients with an HLA-compatible donor.