191 |
Impacts des cannabinoïdes sur la vision: étude anatomique et fonctionnelleCécyre, Bruno 09 1900 (has links)
Le système endocannabinoïde (eCB) est une cible thérapeutique intéressante pour traiter diverses conditions variées, allant de la modulation du système immunitaire à la prise en charge de la douleur neuropathique. De plus, le système eCB est impliqué dans les processus développementaux comme l’indique une exposition aux cannabinoïdes au cours du développement qui provoque des troubles neurofonctionnels. En raison de leur nature lipophile, les eCBs ne sont pas emmagasinés, mais sont plutôt synthétisés et dégradés sur demande par des enzymes. Ainsi, l’étude du patron d’expression de ces enzymes permettrait de mieux comprendre l’expression et ainsi le rôle joué par les eCBs pendant la formation du système nerveux central.
Le récepteur CB1 est grandement distribué dans le système nerveux, alors que le récepteur CB2 est traditionnellement associé au système immunitaire. La découverte récente de l’expression et de l’impact fonctionnel du récepteur CB2 dans certains neurones, notamment au niveau rétinien, modifie la vision traditionnelle des rôles des eCBs. Notamment, une étude de notre laboratoire a montré que la délétion du récepteur CB2 chez des souris transgéniques (cnr2-/-) provoque une augmentation de l’amplitude de l’onde a en électrorétinographie, celle-ci reflétant l’activité des photorécepteurs rétiniens. Cette étude a mis en évidence l’importance du récepteur CB2 dans la vision, du moins au niveau rétinien. Jusqu’à ce jour, aucune étude ne s’est intéressée à l’impact des cannabinoïdes sur l’acuité visuelle.
Nous avons caractérisé la distribution rétinienne des enzymes diacylglycérol lipase alpha (DAGLα) et monoacylglycérol lipase (MAGL), responsables respectivement de la synthèse et de la dégradation du ligand eCB 2-arachidonoyl glycérol (2-AG), pendant le développement postnatal. L’enzyme DAGLα est présente dès la naissance et est grandement distribuée dans la rétine, notamment dans les photorécepteurs, les cellules horizontales, amacrines et ganglionnaires. L’enzyme MAGL apparait plus tardivement et est limitée aux cellules amacrines et de Müller.
Nos résultats fonctionnels indiquent que l’acuité visuelle des animaux cnr2-/- est plus élevée autant chez les adultes que pendant le développement postnatal. L’administration répétée d’un agoniste inverse du récepteur CB2 produit une augmentation de l’acuité visuelle similaire à la délétion du récepteur CB2 par génie génétique et inversement, l’administration d’un agoniste du récepteur CB2 diminue l’acuité visuelle. Enfin, l’administration d’un inhibiteur de l’enzyme MAGL, responsable de la dégradation du 2-AG, induit une diminution de l’acuité visuelle similaire à celle obtenue par un agoniste du récepteur CB2 tandis que l’administration d’un inhibiteur de l’enzyme DAGL, responsable de la synthèse du 2-AG, provoque une augmentation de l’acuité visuelle.
Ces résultats suggèrent que le 2-AG est fortement présent tôt lors du développement rétinien et qu’il pourrait être impliqué dans la maturation structurelle et fonctionnelle de la rétine. De plus, les expériences fonctionnelles ont démontré que les cannabinoïdes affectent non seulement la réponse rétinienne, mais aussi l’acuité visuelle de manière significative. En outre, ces résultats confirment que les cannabinoïdes induisent leurs effets sur la vision exclusivement par le récepteur CB2. Enfin, les résultats de cette thèse accroissent les connaissances actuelles dans un contexte de légalisation grandissante du cannabis à des fins récréatives, puisqu’ils mettent en évidence l’importance des impacts sur l’acuité visuelle. / The endocannabinoid (eCB) system is a great therapeutic target for the treatment of many diseases, ranging from immune system modulation to pain management. This system is implicated in developmental processes as indicated by neurofunctional afflictions following developmental exposition to cannabinoids. Since eCBs are lipophilic, they are not stored in vesicles but rather synthesized and degraded on demand by specific enzymes. Thus, the expression pattern of these enzymes could help to better understand the expression of eCBs, and their role during central nervous system maturation.
The CB1 receptor is strongly distributed in the nervous system, while the CB2 receptor is traditionally associated with the immune system. The recent finding of the CB2 receptor expression and function in some neurons, especially in the retina, changes the dogma associated with cannabinoids. A study from our laboratory found that deletion of the CB2 receptor in transgenic mice (cnr2-/-) enhances the a-wave amplitude in electroretinography, this wave reflecting photoreceptor activity. This report highlighted the importance of the CB2 receptor in vision, at least in the retina. Until now, no study aimed at the impact of cannabinoids on visual acuity.
We characterized the retinal distribution of diacylglycerol lipase alpha (DAGLα) and monoacylglycerol lipase (MAGL) enzymes, responsible for the synthesis and degradation of the eCB ligand 2-arachidonoyl glycerol (2-AG) during postnatal development. The enzyme DAGLα is expressed since birth and is greatly distributed across the retina such as in photoreceptors, horizontal, amacrine and ganglion cells. The enzyme MAGL is expressed later during development and is present only in amacrine and Müller cells.
Our functional results show that the visual acuity of cnr2-/- mice is enhanced in adults and during postnatal development. The repeated administration of a CB2 receptor antagonist yielded a better visual acuity, and inversely a CB2 receptor agonist decreased the visual acuity. Furthermore, the administration of a MAGL inhibitor, the enzyme in charge of 2-AG degradation, induced a strong decrease in visual acuity, similar to that obtained with a CB2 receptor agonist. Inversely, a DAGL inhibitor, the enzyme responsible for 2-AG synthesis, caused an increase in visual acuity.
These results suggest that 2-AG is strongly expressed early during retinal development and could be implicated in structural and functional maturation of the retina. Furthermore, we demonstrated that cannabinoids do not only affect retinal function, but also visual acuity. These results confirm that cannabinoids modulate their visual effects exclusively via the CB2 receptor. Finally, in recent years, many countries legalized cannabis for recreational and therapeutic use. The findings from this thesis increase the understanding of cannabinoids since they highlight the great impact of cannabinoids on the visual acuity.
|
192 |
Risk Factors Associated with the Occurrence of Refractive errors among Secondary School Children in Malamulele Community, Limpopo Province.Khoza, Hllawulani Lizzy 09 1900 (has links)
MPH / Department of Public Health / See the attached abstract below
|
193 |
Visual and Demographic Factors in Bioptic Driving Training and Road SafetyDougherty, Bradley Edward 25 July 2013 (has links)
No description available.
|
194 |
Étude de l'importance de répondre aux besoins visuels en conduite automobile lorsque la demande visuelle et cognitive est fortement sollicitéePatoine, Amigale 08 1900 (has links)
La sécurité routière est un enjeu de santé publique et de développement à travers le monde. En 2010, déjà plus d'un milliard de véhicules à travers le monde étaient en circulation (1). En 2016, près de 1,35 million de personnes ont été rapportées comme décédées suite à des accidents de la route (2). Avec des intérieurs de véhicules et des environnements routiers en constante évolution au cours du dernier siècle, les capacités visuelles sont de plus en plus sollicitées entraînant également une contribution accrue des capacités cognitives. Du point de vue scientifique et clinique, l'interaction entre les mécanismes visuels, tels que l'acuité visuelle et les mécanismes cognitifs impliqués pendant la conduite sont encore peu étudiés et à peine promus comme éléments clés du comportement de conduite sécuritaire. L'étude de cette problématique, dont l'impact est sous-estimé au niveau sociétal, est au coeur de ce travail de maîtrise. Si l'acuité visuelle est difficile à relier aux taux d'accidentologie (3, 4), il est cependant reconnu que les capacités visuo cognitives prédisent le taux d'accidentologie sur route à cinq ans (3) et en simulateur de conduite (5). C’est pourquoi dans cette étude, nous avons émis l'hypothèse que, dans un contexte de forte charge cognitive en conduite, une diminution de l'acuité visuelle aurait un impact négatif sur le comportement de conduite. Nous avons examiné si un seuil d'acuité visuelle artificiellement réduit au seuil légal d'obtention du permis de conduire au Canada, et une réduction plus importante induirait un effet sur les performances de conduite. Le comportement de 21 conducteurs âgés de 21 à 34 ans a été mesuré à l'aide du simulateur VS500M dans divers contextes de conduite et de charge cognitive. Un scénario rural de conduite à faible charge cognitive en comparaison à un scénario autoroute de conduite impliquant des tâches de navigation sur GPS ont été utilisés. Deux scénarios de chaque ont été réalisés avec une vision optimale -acuité visuelle de 6/6- et une qualité de vision réduite -acuité visuelle réduite artificiellement à un niveau plus faible pour 11 des conducteurs et une réduction plus importante pour 10 des conducteurs. Les résultats, faisant l'objet d'une publication scientifique à comité de lecture en préparation, démontrent une diminution des capacités à manoeuvrer le véhicule efficacement, notamment une augmentation de la variabilité de la vitesse et de la position latérale du véhicule (SDLP) en contexte de charge mentale élevée, une augmentation de la variabilité de la vitesse en condition de qualité de vision réduite lors de présence de charge mentale élevée ainsi qu'une diminution de la vitesse moyenne et une augmentation de sa variabilité selon les groupes de réduction de qualité visuelle, toujours dans un contexte de charge mentale élevée. Même si le taux de succès reste stable malgré la manipulation expérimentale, les résultats confirment l'importance d'évaluer les enjeux visuels dans des contextes certes quotidiens, mais pour
2
lesquels les interactions avec la cognition sont encore peu considérées. La sollicitation de la vision à des distances intermédiaires par la tâche de GPS, en plus des distances de loin telles que considérées par les aspects normatifs de la législation du permis de conduire, l'augmentation de la charge cognitive associée à cette double tâche de mobilité et de navigation, mais aussi à la réduction de la qualité de vision nous amènent à proposer de nouvelles pistes de recherche dans la discussion de ce mémoire pour mieux comprendre les enjeux des amétropies visuelles, de la presbytie ou bien encore du vieillissement / Road safety is a public health and development issue across the world. In 2010, more than a billion vehicles were already in circulation worldwide (1). In 2016, nearly 1.35 million people were reported as dead after road crashes (2). With ever-changing vehicle interiors and road environments over the past century, visual abilities are increasingly strained resulting in an increased contribution of cognitive abilities as well. From a scientific and clinical point of view, the interaction between visual mechanisms, such as visual acuity and the cognitive mechanisms involved during driving are still little studied and hardly promoted as key elements of safe driving behavior. The study of this problem, the impact of which is underestimated at the societal level, is at the heart of my master's work. While visual acuity is difficult to relate to accident rates (3, 4), it is however recognized that visuo-cognitive abilities predict the road accident rate at five years (3) and in a driving simulator (5). This is why in this study, we hypothesized that, in a context of high cognitive load while driving, a decrease in visual acuity would have a negative impact on driving behavior. We examined whether a visual acuity threshold artificially reduced to the legal threshold for obtaining a driver's license in Canada, and a greater reduction, would have an effect on driving performance. The behaviors of 21 drivers aged between 21 and 34 were measured using the VS500M simulator in various driving and cognitive load contexts. A rural driving scenario with low cognitive load compared to a highway driving scenario involving GPS navigation tasks were used. Two scenarios were carried out by all the participants with optimal vision - visual acuity of 6/6 - and reduced quality of vision -a lower artificially reduced visual acuity 11 of the drivers and a higher one for 10 of the drivers. The results, which are the subject of a peer-reviewed scientific publication in preparation, demonstrate a decrease in the ability to maneuver the vehicle effectively, in particular an increase in the variability of speed and of the standard deviation of lateral position of the vehicle (SDLP) in a context of high mental load, an increase in the variability of speed under reduced vision quality conditions in the presence of a high mental load as well as a decrease in the average speed and an increase in its variability according to the visual quality reduction groups, also in a context of high mental load. Even if the success rate remains stable despite the experimental manipulation, the results confirm the importance of evaluating visual issues in contexts that are admittedly everyday but for which interactions with cognition are still little considered. The solicitation of vision at intermediate distances by the GPS task, in addition to far distances as considered by the normative aspects of driving license legislation, the increased cognitive load associated with this dual mobility task and navigation, but also to the reduction of the quality of vision lead us to propose new avenues of research in discussion of this thesis to better understand the stakes of visual ametropia, presbyopia or even aging.
|
195 |
Bilateral changes in foveal structure in individuals with amblyopiaBruce, Alison, Pacey, Ian E., Bradbury, J.A., Scally, Andy J., Barrett, Brendan T. January 2013 (has links)
No / To examine foveal structure in amblyopia using spectral-domain optical coherence tomography (SD-OCT). DESIGN: Prospective, cross-sectional study. PARTICIPANTS AND CONTROLS: Two subject groups were recruited to the study: 85 amblyopes (34 adults, 51 children) and 110 visually normal controls (44 adults, 66 children). METHODS: A detailed eye examination, including an SD-OCT scan, was performed in all participants. A total of 390 eyes of 195 subjects were imaged using a 3-dimensional (3D) macula scan covering a nominal 6 x 6-mm area with a resolution of 256 x 256 (65,536 axial scans). Data from the B-scans bisecting the fovea both horizontally and vertically were fitted with a mathematical model of the fovea to determine a range of foveal parameters. MAIN OUTCOME MEASURES: Foveal thickness, foveal pit depth, and foveal pit slope. RESULTS: Bilateral differences between the eyes of amblyopes compared with visually normal controls were found. The difference between foveal structure in amblyopic participants relative to structure in subjects with normal vision persisted even when variables such as age, ethnicity, axial length, and sex were taken into account. Amblyopes showed increased foveal thickness (+8.31 mum; P = 0.006) and a reduction in pit depth in the horizontal meridian (-10.06 mum; P = 0.005) but not in the vertical meridian (P = 0.082) when compared with subjects with normal vision. Foveal pit slopes were found to be approximately 1 degree flatter in the nasal (P = 0.033) and temporal (P = 0.014) meridians in amblyopes, but differences between amblyopes and controls in the superior (P = 0.061) and inferior (P = 0.087) meridians did not reach statistical significance. No statistically significant interocular differences were found in the foveal structure between amblyopic and fellow eyes. CONCLUSIONS: Differences were found in the foveal structure in both eyes of amblyopes compared with subjects with normal vision. These differences consisted of increased foveal thickness, reduced pit depth when measured along the horizontal meridian, and flattening of the nasal and temporal sides of the foveal pit.
|
196 |
Blindness and visual impairment among people with diabetes mellitus 40 years and older in the Limpopo Province, South AfricaMabaso, Raymond 02 September 2013 (has links)
The aim of this study was to determine the prevalence and causes as well as the risk factors of visual impairment (VI) and blindness among Black South Africans with diabetes mellitus (DM) aged 40 years and older in Mopani District, Limpopo province, South Africa.
This was a cross-sectional study in which Black South Africans with DM aged ≥40 years old were examined for VI and blindness. In addition, anthropometric as well as risk factors for VI and blindness were studied. A total of 225 participants were selected from seven Public Health Facilities in Mopani District. Data was collected using standard optometric instruments, anthropometric instruments and structured interviews. Data analysis was done using the Statistical Analysis System (SAS) and Microsoft Excel software packages.
The ages of the participants ranged from 40 to 90 years with a mean of 61.5±10.49 years. There were more females (71.5%) than males (28.4%). The prevalence of uncorrected VI and blindness in the right eyes of the participants was 70.7% and 3.6%, respectively. In the left eyes, it was 72% and 3.1%, respectively. However, following optical correction, the prevalence in right eyes was 41.3% and 3.6%, respectively. In the left eyes, it was 42.2% and 3.1%, respectively.
Risk factors that were individually associated with VI and blindness include age, educational qualification, monthly income, knowledge of DM types, oral DM treatment (pills), losing weight, compliance to losing weight, family history of DM, physical activity, and date of last eye examination .When logistic regression was used, knowledge of DM types, pills, and compliance to losing weight, family history of DM, monthly income and physical activity remained associated with VI and blindness.
The high prevalence of VI in this diabetes population was not primarily due to DM itself, but due to refractive error and cataract,
conditions which have effective and easy treatments. A total of 84% of the participants were visually impaired due to either refractive error or cataract or both and only 3.8% due to diabetes retinopathy. It is therefore recommended that appropriate and affordable refraction and cataract surgical services be made available and accessible to this population / Health Studies / D. Litt. et Phil. (Health Studies)
|
197 |
Wave aberrations in ophthalmic progressive power lenses and impact on visual quality. / Aberraciones en lentes oftálmicas de potencia progresiva y su impacto en la calidad visual.Villegas Ruiz, Eloy Ángel 27 November 2009 (has links)
Las lentes progresivas (LP) para gafas es una solución muy extendida para la presbicia, ya que proporcionan una visión continua a todas las distancias debido a un cambio progresivo de potencia. En este trabajo se han medido las aberraciones de frente de onda espacialmente resueltas y la calidad visual en estas lentes. Además del astigmatismo que aumenta periféricamente, también se han encontrado pequeños valores de aberraciones de tercer orden, coma y trefoil, que producen un bajo deterioro de la calidad óptica y visual. El logaritmo de métricas sobre la PSF del sistema lente con ojo son las que mejor predicen la agudeza visual. Durante la primera semana de adaptación, no se aprecia una mejora significativa de la agudeza visual a través de distintas zonas de las LPs. Al comparar diferentes LPs, las aberraciones, principalmente el astigmatismo, se comporta como un colchón de agua, que se puede mover pero no eliminar. / Progressive lenses (PL) are designed to provide continuous vision at all distances by means a progressive change in spherical power from upper to lower zones. In this thesis, we measure the spatially resolved aberrations and the visual quality of PLs. In addition to astigmatism, third order aberrations, coma and trefoil, are also found in the PLs, but the impact of these aberrations on visual performance is limited. The logarithm of metrics on the PSF of the entire system eye plus PL are the parameters that best predict the visual acuity. There is not a significant improvement of visual acuity through the different zones of the PLs during the first week of adaptation. The current designs of PLs are somehow similar to a waterbed, with the aberrations, mainly astigmatism, being the water: they can be moved but they cannot be eliminated.
|
198 |
Blindness and visual impairment among people with diabetes mellitus 40 years and older in the Limpopo Province, South AfricaMabaso, Raymond 02 September 2013 (has links)
The aim of this study was to determine the prevalence and causes as well as the risk factors of visual impairment (VI) and blindness among Black South Africans with diabetes mellitus (DM) aged 40 years and older in Mopani District, Limpopo province, South Africa.
This was a cross-sectional study in which Black South Africans with DM aged ≥40 years old were examined for VI and blindness. In addition, anthropometric as well as risk factors for VI and blindness were studied. A total of 225 participants were selected from seven Public Health Facilities in Mopani District. Data was collected using standard optometric instruments, anthropometric instruments and structured interviews. Data analysis was done using the Statistical Analysis System (SAS) and Microsoft Excel software packages.
The ages of the participants ranged from 40 to 90 years with a mean of 61.5±10.49 years. There were more females (71.5%) than males (28.4%). The prevalence of uncorrected VI and blindness in the right eyes of the participants was 70.7% and 3.6%, respectively. In the left eyes, it was 72% and 3.1%, respectively. However, following optical correction, the prevalence in right eyes was 41.3% and 3.6%, respectively. In the left eyes, it was 42.2% and 3.1%, respectively.
Risk factors that were individually associated with VI and blindness include age, educational qualification, monthly income, knowledge of DM types, oral DM treatment (pills), losing weight, compliance to losing weight, family history of DM, physical activity, and date of last eye examination .When logistic regression was used, knowledge of DM types, pills, and compliance to losing weight, family history of DM, monthly income and physical activity remained associated with VI and blindness.
The high prevalence of VI in this diabetes population was not primarily due to DM itself, but due to refractive error and cataract,
conditions which have effective and easy treatments. A total of 84% of the participants were visually impaired due to either refractive error or cataract or both and only 3.8% due to diabetes retinopathy. It is therefore recommended that appropriate and affordable refraction and cataract surgical services be made available and accessible to this population / Health Studies / D. Litt. et Phil. (Health Studies)
|
199 |
Avaliação ocular em indivíduos adultos com deficiência isolada e congênita do hormônio do crescimento / Ocular evaluation in adult individuals with isolated and congenital growing hormone deficiencyFaro, Augusto César Nabuco de Araujo 27 January 2017 (has links)
OBJECTIVE: Ocular function is fundamental for environmental adaptation and survival
capacity. Growth factors are necessary for a mature eyeball, needed for adequate vision.
However, the consequences of the deficiency of circulating growth hormone (GH) and its
effector insulin-like growth factor I (IGF-I) on the physical aspects of the human eye are still
debated. A model of untreated isolated GH deficiency (IGHD), with low but measurable
serum GH, may clarify this issue. The aim of this study was to assess the ocular aspects of
adult IGHD individuals who have never received GH therapy.
DESIGN: Cross sectional study.
METHODS: Setting University Hospital, Federal University of Sergipe, Brazil. Patients:
Twenty-five adult (13 males, mean age 50.1 years, range 26 to 70 years old) IGHD subjects
homozygous for a null mutation (c.57+1G>A) in the GHRH receptor gene, and 28 (15 males,
mean age 51.1 years, range 26 to 67 years old) controls were submitted to an endocrine and
ophthalmological assessment. Forty-six IGHD and 50 control eyes were studied. Main
outcome measures: Visual acuity, intraocular pressure (IOP), refraction (spherical
equivalent), ocular axial length (AL), anterior chamber depth (ACD),lens thickness (LT),
vitreous depth (VD), mean corneal curvature (CC) and central corneal thickness (CCT).
RESULTS: IGHD subjects exhibited unmeasurable serum IGF-I levels, similar visual acuity,
intraocular pressure and LT, higher values of spherical equivalent and CC, and lower
measures of AL, ACD, VD and CCT in comparison to controls, but within their respective
normal ranges. While mean stature in IGHD group was 78 % of the control group, mean head
circumference was 92 % and axial AL was 96 %.
CONCLUSIONS: These observations suggest mild ocular effects in adult subjects with
severe IGF-I deficiency due to non-treated IGHD. / OBJETIVO: A função ocular é fundamental para a adaptação ambiental e a
capacidade de sobrevivência. Fatores de crescimento são julgados necessáriospara alcançar
um globo ocular maduro, e conseqüente visão adequada. No entanto, as consequências da
deficiência isoladadohormônio de crescimento circulante (GH) edo seu efetor, o fator de
crescimento semelhante à insulina I (IGF-I) nos aspectos físicos do olho humano ainda são
debatidas. Um modelo de deficiência isolada de GH não tratada (DIGH) pode esclarecer esta
questão. O objetivo deste estudo foi avaliar os aspectos físicos do globo ocular de indivíduos
adultos com DIGH que nunca receberam terapia com GH.
DESENHO: Estudo transversal.
MÉTODOS: Ambiente: Hospital Universitário, Universidade Federal de Sergipe,
Brasil. Pacientes: 25 indivíduosadultos (13 homens,com média de idade de 50,1 anos, entre
26 e 70 anos), com DIGH homozigotos para uma mutação nula (c.57 + 1G> A) no gene do
receptorGHRH do grupo DIGH e 28 controles (15 homens, com média de idade de 51,1 anos,
entre 26 e 67 anos), pareados, foram submetidos à avaliação endócrina e oftalmológica.
Principais medidas: acuidade visual(AV), pressão intraocular(PIO),refração (equivalente
esférico, EE), comprimento axial ocular (CA), profundidade da câmara anterior(PCA),
medida da espessura do cristalino(EC), profundidade do vítreo(PV), curvatura corneana
média(CCM) e espessura central corneana(ECC).
RESULTADOS:Indivíduos com DIGH apresentaram IGF-I sérico não mensurável,
similarAV, PIO e EC, valores mais altos doEEe CCM, e menores valores do CA, PCA, PV e
ECC em comparação com os controles, mas dentro das respectivas faixas normais. Enquanto
a estaturamédia no grupo DIGH foi de 78% do grupo de controle, a média da circunferência
da cabeça foi de 92% e a média docomprimento axial foi de 96%.
CONCLUSÃO: Essas observações sugerem efeitos oculares discretosem indivíduos
adultos com grave deficiência de IGF-I devido à DIGH não tratada.
|
200 |
Avaliação ocular em indivíduos adultos com deficiência isolada e congênita do hormônio do crescimento / Ocular evaluation in adult individuals with isolated and congenital growing hormone deficiencyFaro, Augusto César Nabuco de Araujo 27 January 2017 (has links)
OBJECTIVE: Ocular function is fundamental for environmental adaptation and survival
capacity. Growth factors are necessary for a mature eyeball, needed for adequate vision.
However, the consequences of the deficiency of circulating growth hormone (GH) and its
effector insulin-like growth factor I (IGF-I) on the physical aspects of the human eye are still
debated. A model of untreated isolated GH deficiency (IGHD), with low but measurable
serum GH, may clarify this issue. The aim of this study was to assess the ocular aspects of
adult IGHD individuals who have never received GH therapy.
DESIGN: Cross sectional study.
METHODS: Setting University Hospital, Federal University of Sergipe, Brazil. Patients:
Twenty-five adult (13 males, mean age 50.1 years, range 26 to 70 years old) IGHD subjects
homozygous for a null mutation (c.57+1G>A) in the GHRH receptor gene, and 28 (15 males,
mean age 51.1 years, range 26 to 67 years old) controls were submitted to an endocrine and
ophthalmological assessment. Forty-six IGHD and 50 control eyes were studied. Main
outcome measures: Visual acuity, intraocular pressure (IOP), refraction (spherical
equivalent), ocular axial length (AL), anterior chamber depth (ACD),lens thickness (LT),
vitreous depth (VD), mean corneal curvature (CC) and central corneal thickness (CCT).
RESULTS: IGHD subjects exhibited unmeasurable serum IGF-I levels, similar visual acuity,
intraocular pressure and LT, higher values of spherical equivalent and CC, and lower
measures of AL, ACD, VD and CCT in comparison to controls, but within their respective
normal ranges. While mean stature in IGHD group was 78 % of the control group, mean head
circumference was 92 % and axial AL was 96 %.
CONCLUSIONS: These observations suggest mild ocular effects in adult subjects with
severe IGF-I deficiency due to non-treated IGHD. / OBJETIVO: A função ocular é fundamental para a adaptação ambiental e a
capacidade de sobrevivência. Fatores de crescimento são julgados necessáriospara alcançar
um globo ocular maduro, e conseqüente visão adequada. No entanto, as consequências da
deficiência isoladadohormônio de crescimento circulante (GH) edo seu efetor, o fator de
crescimento semelhante à insulina I (IGF-I) nos aspectos físicos do olho humano ainda são
debatidas. Um modelo de deficiência isolada de GH não tratada (DIGH) pode esclarecer esta
questão. O objetivo deste estudo foi avaliar os aspectos físicos do globo ocular de indivíduos
adultos com DIGH que nunca receberam terapia com GH.
DESENHO: Estudo transversal.
MÉTODOS: Ambiente: Hospital Universitário, Universidade Federal de Sergipe,
Brasil. Pacientes: 25 indivíduosadultos (13 homens,com média de idade de 50,1 anos, entre
26 e 70 anos), com DIGH homozigotos para uma mutação nula (c.57 + 1G> A) no gene do
receptorGHRH do grupo DIGH e 28 controles (15 homens, com média de idade de 51,1 anos,
entre 26 e 67 anos), pareados, foram submetidos à avaliação endócrina e oftalmológica.
Principais medidas: acuidade visual(AV), pressão intraocular(PIO),refração (equivalente
esférico, EE), comprimento axial ocular (CA), profundidade da câmara anterior(PCA),
medida da espessura do cristalino(EC), profundidade do vítreo(PV), curvatura corneana
média(CCM) e espessura central corneana(ECC).
RESULTADOS:Indivíduos com DIGH apresentaram IGF-I sérico não mensurável,
similarAV, PIO e EC, valores mais altos doEEe CCM, e menores valores do CA, PCA, PV e
ECC em comparação com os controles, mas dentro das respectivas faixas normais. Enquanto
a estaturamédia no grupo DIGH foi de 78% do grupo de controle, a média da circunferência
da cabeça foi de 92% e a média docomprimento axial foi de 96%.
CONCLUSÃO: Essas observações sugerem efeitos oculares discretosem indivíduos
adultos com grave deficiência de IGF-I devido à DIGH não tratada.
|
Page generated in 0.0377 seconds