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Retinal Lesions (retinal + lesion)
Selected AbstractsAstrocytic hamartoma: a case reportCLINICAL AND EXPERIMENTAL OPTOMETRY, Issue 2 2008Lorne B Yudcovitch OD MS FAAO A 13-year-old Romanian boy presented to the eye clinic with a chief complaint of blurred distance and near vision. The patient reported a history of a boil on his neck that was removed in Russia one year ago. Cover testing demonstrated bilateral end point nystagmus and exotropia. Ocular health evaluation revealed an astrocytic hamartoma and oculo-rotary nystagmus. Referral to a retinal specialist helped confirm the diagnosis of astrocytic hamartoma but did not elucidate on the possible aetiology of the lesion or rule out tuberous sclerosis as the causative agent, as the patient was lost to follow-up. Based on fundus signs along with the nystagmus, neuro-imaging studies are indicated to rule out any intracranial masses that may be present. The most important differential diagnosis that must excluded is retinoblastoma, which can closely resemble astrocytic hamartoma. The suspicion of tuberous sclerosis was also considered as a potential cause of the retinal lesion, based on clinical signs. The prognosis for astrocytic hamartomas is relatively good, although until tuberous sclerosis is ruled out, caution should be exercised and serial ophthalmic evaluations should continue. [source] Eph/ephrin expression in the adult rat visual system following localized retinal lesions: localized and transneuronal up-regulation in the retina and superior colliculusEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 8 2005J. Rodger Abstract Following unilateral optic nerve section in adult PVG hooded rat, the axon guidance cue ephrin-A2 is up-regulated in caudal but not rostral superior colliculus (SC) and the EphA5 receptor is down-regulated in axotomised retinal ganglion cells (RGCs). Changes occur bilaterally despite the retino-collicular projection being mostly crossed. Here we investigate the dynamics of Eph/ephrin expression using in situ hybridization and semi-quantitative immunohistochemistry after localized retinal lesions. Unilateral krypton laser lesions to dorso-nasal retina ablated contralaterally projecting RGCs (DN group); ventro-temporal lesions ablated contralaterally and ipsilaterally projecting RGCs (VT group). Lesions of the entire retina served as controls (Total group). Results are compared to normal animals in which tectal ephrin-A2 and retinal EphA5 are expressed, respectively, as shallow ascending rostro-caudal and naso-temporal gradients. In both SCs of DN and Total groups, tectal ephrin-A2 was up-regulated caudally; in the VT group, expression remained normal bilaterally. Unilateral collicular ablation indicated that bilateral changes in ephrin-A2 expression are mediated via intercollicular pathways. EphA5 expression in the VT group was elevated in the intact nasal region of experimental retinae. For each experimental group, EphA5 expression was also elevated in nasal retina of the opposite eye, resulting in uniform expression across the naso-temporal axis. Up-regulation of ephrin-A2 in caudal, but not rostral, SC suggests the enhancement of developmental positional information as a result of injury. Bilateral increases in retinal EphA5 expression demonstrate that signals for up-regulation operate interocularly. The study demonstrates that signals regulating guidance cue expression are both localized and relayed transneuronally. [source] Glutamate levels and transport in cat (Felis catus) area 17 during cortical reorganization following binocular retinal lesionsJOURNAL OF NEUROCHEMISTRY, Issue 6 2003Ann Massie Abstract Glutamate is known to play a crucial role in the topographic reorganization of visual cortex after the induction of binocular central retinal lesions. In this study we investigated the possible involvement of the glial high-affinity Na+/K+ -dependent glutamate transporters in cortical plasticity using western blotting and intracortical microdialysis. Basal extracellular glutamate levels and the re-uptake activity for glutamate have been determined by comparing the extracellular glutamate concentration before and during the blockage of glutamate removal from the synaptic cleft with the potent transporter inhibitor l - trans -pyrrolidine-3,4-dicarboxylic acid. In cats with central retinal lesions we observed increased basal extracellular glutamate concentrations together with a decreased re-uptake activity in non-deprived, peripheral area 17, compared with the sensory-deprived, central cortex of the same animal as well as the topographically matching regions of area 17 in normal subjects. Western blotting experiments revealed a parallel decrease in the expression level of the glial glutamate transporter proteins GLT-1 and GLAST in non-deprived cortex compared with sensory-deprived cortex of lesion cats and the corresponding regions of area 17 of normal subjects. This study shows that partial sensory deprivation of the visual cortex affects the removal of glutamate from the synaptic cleft and implicates a role for glial,neuronal interactions in adult brain plasticity. [source] Spontaneous Feline Hypertension: Clinical and Echocardiographic Abnormalities, and Survival RateJOURNAL OF VETERINARY INTERNAL MEDICINE, Issue 1 2003Valerie Chetboul Systemic hypertension was diagnosed in 58 of 188 untreated cats referred for evaluation of suspected hypertension-associated ocular, neurologic, cardiorespiratory, and urinary disease, or diseases frequently associated with hypertension (hyperthyroidism and chronic renal failure). Hypertensive cats were significantly older than normotensive subjects (13.0 ± 3.5 years versus 9.6 ± 5.0 years; P < .01), and had a greater prevalence of retinal lesions (48 versus 3%; P < .001), gallop rhythm (16 versus 0%; P < .001), and polyuria-polydipsia (53 versus 29%; P < .01). Blood pressure was significantly higher (P < .001) in cats with retinopathies (262 ± 34 mm Hg) than in other hypertensive animals (221 ± 34 mm Hg). Hypertensive cats had a thicker interventricular septum (5.8 ± 1.7 versus 3.7 ± 0.64 mm; P < .001) and left ventricular free wall (6.2 ± 1.6 versus 4.1 ± 0.51 mm; P < .001) and a reduced diastolic left ventricular internal diameter (13.5 ± 3.2 versus 15.8 ± 0.72 mm; P < .001) than control cats. Left ventricular geometry was abnormal in 33 of 39 hypertensive subjects. No significant difference was found in age or blood pressure at the initial visit between cats that died or survived over a 9-month period after initial diagnosis of hypertension. Mean survival times were not significantly different between hypertensive cats with normal and abnormal left ventricular patterns. Further prospective studies are needed to clearly identify the factors involved in survival time in hypertensive cats. [source] Taurine deficiency is a cause of vigabatrin-induced retinal phototoxicity,ANNALS OF NEUROLOGY, Issue 1 2009Firas Jammoul MD Objective Although vigabatrin irreversibly constricts the visual field, it remains a potent therapy for infantile spasms and a third-line drug for refractory epilepsies. In albino animals, this drug induces a reduction in retinal cell function, retinal disorganization, and cone photoreceptor damage. The objective of this study was to investigate the light dependence of the vigabatrin-elicited retinal toxicity and to screen for molecules preventing this secondary effect of vigabatrin. Methods Rats and mice were treated daily with 40 and 3mg vigabatrin, respectively. Retinal cell lesions were demonstrated by assessing cell function with electroretinogram measurements, and quantifying retinal disorganization, gliosis, and cone cell densities. Results Vigabatrin-elicited retinal lesions were prevented by maintaining animals in darkness during treatment. Different mechanisms including taurine deficiency were reported to produce such phototoxicity; we therefore measured amino acid plasma levels in vigabatrin-treated animals. Taurine levels were 67% lower in vigabatrin-treated animals than in control animals. Taurine supplementation reduced all components of retinal lesions in both rats and mice. Among six vigabatrin-treated infants, the taurine plasma level was found to be below normal in three patients and undetectable in two patients. Interpretation These results indicate that vigabatrin generates a taurine deficiency responsible for its retinal phototoxicity. Future studies will investigate whether cotreatment with taurine and vigabatrin can limit epileptic seizures without inducing the constriction of the visual field. Patients taking vigabatrin could gain immediate benefit from reduced light exposures and dietetic advice on taurine-rich foods. Ann Neurol 2009;65:98,107 [source] Ocular Changes after Intravitreal Injection of Methanol, Formaldehyde, or Formate in RabbitsBASIC AND CLINICAL PHARMACOLOGY & TOXICOLOGY, Issue 2 2001Yoriko Hayasaka One hundred ,l of 1% methanol, 1% or 0.1% formaldehyde, or 1% formate was injected in the vitreous cavity of the right eyes of rabbits. The eyes were examined by biomicroscopy and ophthalmoscopy weekly. One month after injection, the eyes were enucleated and examined histologically. One week after treatment the animals that received 0.1% formaldehyde showed retinal vessel dilation, and the rabbits that received 1% formaldehyde showed mild posterior subcapsular cataract and retinal vessel dilation and haemorrhages. One month after treatment, the animals that received 0.1% or 1% formaldehyde developed mild posterior subcapsular cataract and retinal lesions. Animals that received 1% methanol or 1% formate showed nearly normal optical media and fundi. Histologically disorganized retina and optic nerve were seen in eyes that received 0.1% or 1% formaldehyde. Eyes that received 1% methanol or 1% formate appeared histologically normal. Our findings indicate that intravitreal injection of formaldehyde causes retinal and optic nerve damage, while methanol and formate are not or less toxic to ocular tissues. [source] The North Jutland County Diabetic Retinopathy Study (NCDRS)ACTA OPHTHALMOLOGICA, Issue 4 2010Clinically significant macular oedema, retinal lesions, visual acuity Abstract. Purpose:, This study set out to map the associations between retinal lesions, visual acuity (VA) and the presence of clinically significant macular oedema (CSMO) in diabetes subjects. Methods:, This cross-sectional study comprised 656 type 1 and 328 type 2 diabetes subjects undergoing retinopathy screening in the County of North Jutland, Denmark. Numbers of specific retinal lesions were quantified from retinal photographic recordings. Associations between CSMO, number of specific retinal lesions and VA were established. The percentages of eyes with CSMO ascribed to retinal lesions were calculated. Results:, The presence of CSMO, number of specific retinal lesions and VA were all significantly associated. The parameter with the highest statistical association with CSMO measured by Spearman's correlation coefficient was hard exudates (type 1: 0.524; type 2: 0.715), followed by microaneurysms (type 1: 0.298; type 2: 0.508), retinal haemorrhages (type 1: 0.227; type 2: 0.595), cottonwool spots (type 1: 0.207; type 2: 0.259) and VA (type 1: , 0.137; type 2: , 0,175). Conclusions:, All retinal lesions are significantly associated with CSMO and together can predict for up to 42.3% (in type 1 diabetes) and 64.3% (in type 2 diabetes) of CSMO cases. [source] Computer-assisted training system for pars plana vitrectomyACTA OPHTHALMOLOGICA, Issue 6 2003Jost B. Jonas Abstract. Purpose:,To evaluate whether microsurgical steps in vitreoretinal surgery can be taught by a computer-assisted training system. Methods:,This prospective, randomized experimental study included 14 ophthalmic residents and medical students who were completely inexperienced in microsurgery. They were randomized into two groups. The study group underwent training programmes in a computer-assisted training system for simulation of pars plana vitrectomy. The control group did not participate in any in vitro training. In the second phase of the study, participants of both groups performed a pars plana vitrectomy in three pig eyes, which included picking a metallic foreign body from the retinal surface. Results:,The amount of retinal detachment and the number of retinal defects at the end of the vitrectomies were smaller, the time needed to remove the foreign body was shorter, the number of retinal lesions associated with the foreign body removal was lower, and the mark given was better in the trained study group than in the untrained group. The relatively small number of study participants did not allow the differences between the study and control groups to reach the 5% level of error probability. Conclusions:,In an animal model, training by a computer-based medical work station for simulation of pars plana vitrectomy showed better outcome measures for trained study participants compared with untrained study participants. Future studies may show whether further refinements of such training programmes will result in statistically significantly better results in surgical outcome parameters. [source] | |||||||||||||