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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Poor Glycemic Control Predicts Increased Neuro-retinal Dysfunction in Adolescents with Type 1 Diabetes

Lakhani, Ekta 15 February 2010 (has links)
Studies demonstrate localized neuro-retinal dysfunction in patients with diabetes and no visible diabetic retinopathy (DR). Poor glycemic control is a strong risk factor for DR. We hypothesized that poor glycemic control predicts increased areas of localized neuro-retinal dysfunction in patients with diabetes. Forty-eight adolescents with diabetes and 45 controls were tested using the standard (103 hexagons) multifocal electroretinogram (mfERG). Negative binomial regression analysis was conducted with number of abnormal hexagons (delayed responses) as the dependent variable and glycated hemoglobin (HbA1c), disease duration, age and sex as covariates. Results indicate that a one-unit increase in HbA1c predicts an 80% (p = 0.002) increase in the number of abnormal hexagons when controlling for age. Increased areas of neuro-retinal dysfunction are predicted by worsening glycemic control in patients with no visible DR. Standard mfERG may be useful in monitoring patients with diabetes and identifying those who may be at risk of developing DR.
2

Poor Glycemic Control Predicts Increased Neuro-retinal Dysfunction in Adolescents with Type 1 Diabetes

Lakhani, Ekta 15 February 2010 (has links)
Studies demonstrate localized neuro-retinal dysfunction in patients with diabetes and no visible diabetic retinopathy (DR). Poor glycemic control is a strong risk factor for DR. We hypothesized that poor glycemic control predicts increased areas of localized neuro-retinal dysfunction in patients with diabetes. Forty-eight adolescents with diabetes and 45 controls were tested using the standard (103 hexagons) multifocal electroretinogram (mfERG). Negative binomial regression analysis was conducted with number of abnormal hexagons (delayed responses) as the dependent variable and glycated hemoglobin (HbA1c), disease duration, age and sex as covariates. Results indicate that a one-unit increase in HbA1c predicts an 80% (p = 0.002) increase in the number of abnormal hexagons when controlling for age. Increased areas of neuro-retinal dysfunction are predicted by worsening glycemic control in patients with no visible DR. Standard mfERG may be useful in monitoring patients with diabetes and identifying those who may be at risk of developing DR.
3

Avaliação morfológica e funcional da retina de pacientes com esclerose múltipla e espectro da neuromielite óptica usando os eletrorretinogramas de campo total e multifocal e a tomografia de coerência óptica / Morphological and functional evaluation of the retina of patients with multiple sclerosis and neuromyelitis optica using full field electroretinogram, multifocal electroretinography and optical coherence tomography

Filgueiras, Thiago Gomes 25 March 2019 (has links)
Objetivos: avaliar as alterações morfofuncionais da retina de pacientes com esclerose múltipla (EM) e espectro da neuromielite óptica (ENMO), com ou sem histórico de neurite óptica (NO), por meio de eletrorretinografia de campo total e multifocal (ERGct / ERGmf) e a tomomografia de coerência óptica (TCO). Avaliar as correlações de tais achados entre si e com o potencial evocado visual (PEV), o campo visual (CV) e a sensibilidade ao contraste (SC). Métodos: Pacientes com EM (n = 30), ENMO (n = 30) e controles (n = 29) foram submetidos a avaliação oftalmológica completa incluindo CV, TCO, ERGct, ERGmf, PEV e medida da SC. Os olhos foram distribuídos em 5 grupos: EM com ou sem história de NO (EM + NO e EM - NO), ENMO com ou sem NO (ENMO + NO e ENMO - NO) e controles. Com a TCO foram medidas as espessuras das camadas de fibras nervosas da retina na região macular (CFNRm), camada de células ganglionares (CCG), camada plexiforme interna (CPI), camada nuclear interna (CNI), camada plexiforme externa (CPE), camada nuclear externa (CNE), complexo camada de fotorreceptores + epitélio pigmentário da retina(CFR+EPR) e da camada de fibras nervosas peripapilar (CFNRp). Dados das ondas a, b e potenciais oscilatórios (POs) do ERGct, medidas de amplitude e latência de N1 e P1 do ERGmf, ondas do PEV e medidas do desvio da normalidade do CV foram analisados. Os grupos foram comparados usando equações estimadas generalizadas. Correlações entre as medidas foram avaliadas. Resultados: Redução da sensibilidade do desvioda normalidade do CV, da SC e aumento da latência das ondas do PEV foram identificadas para ambos os grupos. Nos pacientes ENMO+NO apresentaram redução de amplitude ao PEV em relação aos controles, diferentemente aos demais grupos. As medidas de espessura da CCG e da CPI foram significativamente menores nos grupos de olhos dos pacientes em relação aos controles. A RNFLm foi menor em todos os grupos de olhos de pacientes, exceto o grupo ENMO-NO. Não foi observada diferença significativa entre os grupos de olhos estudados nas comparações referenetes às demais camadas da retina. Comparado aos controles, as amplitudes do POs foram maiores nos olhos de pacientes com ENMO, enquanto as latências de N1 e P1 do ERGmf foram menor nos olhos de pacientes com EM. Essas anormalidades foram fortemente correlacionadas com a espessura da camada retiniana intermediária e externa. Os achados do PEV, assim como do CV e SC, se correlacionaram fortemente com as camadas retinianas. Conclusões: as camadas retinianas internas se mostraram reduzidas à TCO tanto nos olhos de pacientes com EM quanto no naqueles com ENMO, mas os achados POs e ERGmf sugerem também envolvimento das outras camadas retinianas nessas afecções. O PEV apresentou alterações distintas para cada doença. O uso combinado da TCO, do ERG e PEV podem ajudar a entender como as duas condições diferem em relação aos danos retinianos / Objectives: To evaluate the morphofunctional alterations of the retina of patients with multiple sclerosis (MS) and spectrum of neuromyelitis optica spectrum disorder (NMOSD), with or without a history of optic neuritis (ON), using full field electroretinogram (ERG) and multifocal electroretinography (mf- ERG) and optical coherence tomography (OCT). To evaluate the correlations of such findings among themselves and with visual evoked potential (VEP), visual field (VF) and contrast sensitivity (CS). Methods: Patients with MS (n = 30), NMOSD (n = 30) and healthy controls (n = 29) were submitted to a complete ophthalmologic evaluation including VF, OCT, ERG, mf-ERG, VEP and SC measurement. The eyes were distributed in 5 groups: MS with or without history of ON (MS + ON and MS - ON), NMOSD with or without ON (NMOSD + ON and NMOSD - ON) and controls. With the OCT were measured the thickness of the retinal nerve fiber layers in the macular region (mRNFL), ganglion cell layer (GCL), inner plexiform layer (IPL), inner nuclear layer (INL), outer plexiform layer (OPL), outer nuclear layer (ONL), photoreceptor layer (PHOT) and peripapillary retinal nerve fiber layer (pRNFL). The data of the a- and b-waves and oscillatory potentials (OPs) of the ERG, amplitude and peak time of N1 and P1 of mf-ERG, waves of the VEP and VF deviation were analyzed. The groups were compared using generalized estimating equations. Correlations between measurements were evaluated. Results: Reduction of the oVF deviation, CS and increased VEP wave\'s peak times were identified for both groups. In the NMOSD + ON patients, an amplitude redeuction was found in the VEP in relation to the controls, unlike the other groups. The thickness of GCL and IPL was significantly lower in patients\' eyes than controls. mRNFL was lower in all patients, but NMOSD-ON. No significant difference was observed for the remaining layers. Compared to controls, the amplitudes of the POs were higher in the NMOSD group, whereas the mf-ERG\'s N1 and P1 peak time was lower in the MS patients. These abnormalities were strongly correlated with the thickness of the intermediate and outer retinal layers. The findings of the VEP, as well as the VF and SC, correlated strongly with the retinal layers. Conclusions: the inner retinal layers were reduced in both the MS and the NMOSD, but the findings OPs and mf-ERG suggest involvement of the other retinal layers. The VEP presented different alterations for each disease. The combination of OCT, ERG and VEP may help to understand how the two conditions differ in relation to retinal damage
4

Localizing Structural and Functional Damage in the Neural Retina of Adolescents with Type 1 Diabetes

Tan, Wylie 27 November 2012 (has links)
Studies demonstrate neuro-retinal damage in patients with diabetes and no clinically visible diabetic retinopathy. It is unknown which retinal regions are most vulnerable to diabetes. We hypothesized that the standard and slow-flash (sf-) multifocal electroretinogram (mfERG) and adaptive optics (AO) imaging will localize retinal regions of vulnerability. Fifty-five adolescents with diabetes and 54 controls underwent mfERG testing to isolate predominately retinal bipolar cell activity and sf-mfERG testing to isolate three oscillatory potentials (OPs) from intraretinal amacrine and interplexiform cells. Greatest mfERG delays were in the superior temporal quadrant and at 5°-10° eccentricity. Greatest sf-mfERG delays were found at different eccentricities for each OP. Twenty adolescents with diabetes and 14 controls underwent AO imaging. No significant differences in cone photoreceptor density were found; however, patients showed a trend towards reduced density in the superior nasal region. Inner retinal structures may be more susceptible to damage by diabetes than outer retinal structures.
5

Localizing Structural and Functional Damage in the Neural Retina of Adolescents with Type 1 Diabetes

Tan, Wylie 27 November 2012 (has links)
Studies demonstrate neuro-retinal damage in patients with diabetes and no clinically visible diabetic retinopathy. It is unknown which retinal regions are most vulnerable to diabetes. We hypothesized that the standard and slow-flash (sf-) multifocal electroretinogram (mfERG) and adaptive optics (AO) imaging will localize retinal regions of vulnerability. Fifty-five adolescents with diabetes and 54 controls underwent mfERG testing to isolate predominately retinal bipolar cell activity and sf-mfERG testing to isolate three oscillatory potentials (OPs) from intraretinal amacrine and interplexiform cells. Greatest mfERG delays were in the superior temporal quadrant and at 5°-10° eccentricity. Greatest sf-mfERG delays were found at different eccentricities for each OP. Twenty adolescents with diabetes and 14 controls underwent AO imaging. No significant differences in cone photoreceptor density were found; however, patients showed a trend towards reduced density in the superior nasal region. Inner retinal structures may be more susceptible to damage by diabetes than outer retinal structures.

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