Le glaucome représente la première cause de cécité irréversible à l’échelle mondiale. C’est une maladie neuro-dégénérative caractérisée traditionnellement par une pression intraoculaire (PIO) élevée, un dommage du nerf optique et un défaut du champ visuel correspondant. En fait, la PIO élevée constitue le facteur de risque central associé au développement du glaucome. Cependant, en dépit d’un contrôle adéquat de la PIO, la maladie continue à progresser chez certains patients. Cela montre qu’il existe d’autres facteurs impliqués dans la pathogenèse du glaucome. Des études récentes indiquent qu’un dérèglement de l’oxygène est associé à son développement. En utilisant une nouvelle technologie multi-spectrale capable de mesurer la saturation en oxygène (SaO2) dans les structures capillaires de la rétine, cette étude tentera de déterminer si un état d’oxygénation anormal pourrait se retrouver à la papille optique des patients souffrant de glaucome. Une meilleure compréhension du rôle de l’oxygène pourrait aider à améliorer le pronostic du glaucome. Les résultats de l’étude indiquent que le facteur de position (supérieure, temporale et inférieure de la papille optique) n’a aucun effet sur la mesure SaO2 ainsi que sa variabilité chez les patients normaux. La comparaison de la SaO2 entre les sujets normaux et glaucomateux ne montre pas de différence statistiquement significative. En conclusion, la SaO2 «normale» mesurée dans les yeux glaucomateux n'exclut pas nécessairement que l'hypoxie ne soit pas impliquée dans la pathogenèse. Au moment de l’étude, la PIO était bien contrôlée par des médicaments topiques, ce qui pourrait influencer l’oxygénation à la papille optique. / Glaucoma is the leading cause of irreversible blindness worldwide. Traditionally, open-angle glaucoma was defined as a neurodegenerative disease characterized by high intraocular pressure (IOP), progressive retinal cell death with subsequent visual field loss. Elevated IOP has been identified as one of the major risk factors for glaucomatous optic nerve damage. However, adequate IOP control cannot prevent progression of the disease in all patients suggesting that there are other factors involved in the pathogenesis of glaucoma. Recent studies suggest that hypoxia may contribute to the development of glaucoma. Using a new multi-spectral detection system of oxygen saturation (O2Sa), this study determined whether an abnormal state of oxygenation at the optic disc could be found in glaucoma patients. Knowledge about the influence of the oxygen in glaucoma may help to improve the pronostic of the disease. The results of the study indicate that the position factor (superior, temporal and inferior of the optic nerve head) has no effect on the measurement of O2Sa and its variability in normal patients. Comparing the O2Sa between normal subjects and glaucoma subjects shows no statistically significant difference. In conclusion, the «normal» O2Sa measured in glaucomatous eyes does not necessarily exclude that hypoxia is not involved in the pathogenesis of glaucoma because glaucoma patients were under treatment with topical drops that lowered IOP. These medicines could affect the oxygenation of the optic disc.

OBJETIVO: avaliar a reprodutibilidade da curva tensional modificada e do teste de sobrecarga hídrica em portadores de glaucoma de ângulo aberto ou hipertensos oculares, sem uso de hipotensor ocular, em dois dias consecutivos. MÉTODOS: análise prospectiva de pacientes portadores de glaucoma de ângulo aberto ou hipertensos oculares, submetidos à curva tensional modificada (medida da pressão intraocular às 8h, 11h, 14h e 16h), seguida do teste de sobrecarga hídrica (três medidas com intervalo de 15 minutos, iniciando-se 15 minutos após a ingestão, em cinco minutos, de um litro de água em temperatura ambiente), realizados pelo mesmo examinador, em dois dias consecutivos. Foram avaliadas: a reprodutibilidade da pressão intraocular em cada horário de medida durante a curva tensional modificada; a reprodutibilidade da pressão intraocular média, flutuação e pico de pressão durante a curva tensional modificada; a reprodutibilidade da flutuação e do pico de pressão durante o teste de sobrecarga hídrica. Calculou-se o coeficiente de correlação intraclasse para cada parâmetro. RESULTADOS: oitenta e oito olhos de 88 pacientes foram estudados. Destes, 64 eram portadores de glaucoma de ângulo aberto. A média das idades dos participantes foi 68,7+10,8 (51-79) anos. 65% dos pacientes eram do sexo feminino. A curva tensional modificada apresentou coeficiente de correlação intraclasse igual a 0,80, 0,82, 0,83 e 0,86 para as medidas realizadas às 8h, 11h, 14h e 16h, respectivamente (p < 0,001). A flutuação da pressão durante a curva tensional modificada, calculada pela diferença entre as pressões máxima e mínima e pelo desvio-padrão da média das medidas diurnas de pressão, a pressão média e o pico pressórico apresentaram coeficientes 0,60, 0,62, 0,91 e 0,85, respectivamente (p < 0,001). Durante o teste de sobrecarga hídrica, a flutuação apresentou coeficiente de 0,37 e o pico pressórico, 0,79. (p < 0,001). CONCLUSÕES: neste estudo, as medidas de pressão intraocular realizadas durante a curva tensional modificada, a média e o pico apresentaram excelentes níveis de reprodutibilidade. O pico pressórico durante o teste de sobrecarga hídrica apresentou também excelente reprodutibilidade. A flutuação, tanto na curva tensional modificada, quanto no teste de sobrecarga hídrica, apresentou os menores índices de reprodutibilidade / OBJECTIVE: to evaluate the reproducibility of the modified daily tension curve and the water drinking test in patients with open-angle glaucoma or ocular hypertension, not under topical treatment, during two consecutive days. METHODS: prospective analysis of open-angle glaucoma or ocular hypertensive patients, submitted to a modified daily tension curve (intraocular pressure measurements at 8AM, 11AM, 2PM and 4PM), followed by the water drinking test (three intraocular pressure measurements with 15 minutes intervals, 15 minutes after ingestion of one liter of tap water), performed by the same examiner, within two consecutive days. The following parameters were evaluated for reproducibility: intraocular pressure obtained at each time-point during the modified daily tension curve; mean, peak and pressure fluctuation during the curve and peak and fluctuation during the water drinking test. Reproducibility was assessed using the intraclass correlation coefficient. RESULTS: eighty-eight eyes from 88 patients were studied. From these, 64 presented open-angle glaucoma. Mean age was 68.7+10.8 (51-79) years. 65% patients were female. Intraclass correlation coefficients were 0.80, 0.82, 0.83 and 0.86 for intraocular pressure measurements at 8AM, 11AM, 2PM and 4PM, respectively (p<0.001) Fluctuation calculated as the difference between maximum and minimum intraocular pressures, fluctuation calculated as the standard deviation of the four daily measurements, mean and peak pressures presented coefficients of 0.60, 0.62, 0.91 and 0.85, respectively (p<0.001). During the water drinking test, coefficient values for fluctuation and peak pressure were 0.37 and 0.79 (p<0.001). CONCLUSIONS: in this study, intraocular pressure measurements during a modified daily tension curve, mean intraocular pressure and pressure peaks presented excellent reproducibility levels; pressure peaks during the water drinking test also presented excellent reproducibility level, whereas fluctuation, both during the modified daily tension curve and during the water drinking test, was the least reproducible parameter

Background: Compare Goldmann applanation tonometer (GAT) prism and correcting applanation tonometry surface (CATS) prism to intracameral intraocular pressure (IOP), in vivo and in vitro. Methods: Pressure transducer intracameral IOP was measured on fifty-eight (58) eyes undergoing cataract surgery and the IOP was modulated manometrically to 10, 20, and 40 mmHg. Simultaneously, IOP was measured using a Perkins tonometer with a standard GAT prism and a CATS prism at each of the intracameral pressures. Statistical comparison was made between true intracameral pressures and the two prism measurements. Differences between the two prism measurements were correlated to central corneal thickness (CCT) and corneal resistance factor (CRF). Human cadaver eyes were used to assess measurement repeatability. Results: The CATS tonometer prism measured closer to true intracameral IOP than the GAT prism by 1.7+/-2.7 mmHg across all pressures and corneal properties. The difference in CATS and GAT measurements was greater in thin CCT corneas (2.7+/-1.9 mmHg) and low resistance (CRF) corneas (2.8+/-2.1 mmHg). The difference in prisms was negligible at high CCT and CRF values. No difference was seen in measurement repeatability between the two prisms. Conclusion: A CATS prism in Goldmann tonometer armatures significantly improve the accuracy of IOP measurement compared to true intracameral pressure across a physiologic range of IOP values. The CATS prism is significantly more accurate compared to the GAT prism in thin and less rigid corneas. The in vivo intracameral study validates mathematical models and clinical findings in IOP measurement between the GAT and CATS prisms.

Background: Goldmann applanation tonometry (GAT) error relative to intracameral intraocular pressure (IOP) has not been examined comparatively in both human cadaver eyes and in live human eyes. Futhermore, correlations to biomechanical corneal properties and positional changes have not been examined directly to intracameral IOP and GAT IOP. Methods: Intracameral IOP was measured via pressure transducer on fifty-eight (58) eyes undergoing cataract surgery and the IOP was modulated manometrically on each patient alternately to 10, 20, and 40 mmHg. IOP was measured using a Perkins tonometer in the supine position on 58 eyes and upright on a subset of 8 eyes. Twenty one (21) fresh human cadaver globes were Intracamerally IOP adjusted and measured via pressure transducer. Intracameral IOP ranged between 5 and 60 mmHg. IOP was measured in the upright position with a Goldmann Applanation Tonometer (GAT) and supine position with a Perkins tonometer. Central corneal thickness (CCT) was also measured. Results: The Goldmann-type tonometer error measured on live human eyes was 5.2 +/- 1.6 mmHg lower than intracameral IOP in the upright position and 7.9 +/- 2.3 mmHg lower in the supine position (p <.05). CCT also indicated a sloped correlation to error (correlation coeff. = 0.18). Cadaver eye IOP measurements were 3.1+/-2. 5 mmHg lower than intracameral IOP in the upright position and 5.4+/- 3.1 mmHg in the supine position (p <.05). Conclusion: Goldmann IOP measures significantly lower than true intracameral IOP by approximately 3 mmHg in vitro and 5 mmHg in vivo. The Goldmann IOP error is increased an additional 2.8 mmHg lower in the supine position. CCT appears to significantly affect the error by up to 4 mmHg over the sample size.

Il est généralement accepté que les lits vasculaires oculaires auraient la faculté d’autoréguler leur apport sanguin afin de contrebalancer les variations de pression de perfusion oculaire (PPO). Plusieurs études ont tenté d’évaluer ce mécanisme en mesurant les effets d’une variation de la PPO - induite par un exercice ou par une augmentation de la pression intra-oculaire (PIO) à l’aide d’une suction sclérale - sur le débit sanguin oculaire (DSO). Or, les méthodes de mesure du DSO utilisées jusqu'à maintenant présentent de nombreux désavantages et limites, ce qui rend difficile leur usage clinique. De récents développements dans le domaine des investigations non-invasives des paramètres sanguins oculaires proposent un modèle capable de mesurer en temps réel la concentration en oxygène, un autre paramètre important du métabolisme rétinien. Dans le cadre de la présente étude, ce nouveau modèle est utilisé afin de mesurer les effets d’un effort physique dynamique sur la concentration d’oxygène dans les capillaires de la tête du nerf optique (COTNO) de sujets jeunes et en santé. Six jeunes hommes non fumeurs ont participé à l’étude. L’effort physique dynamique consistait en une séance de bicyclette stationnaire de 15 minutes menant à une augmentation du pouls à 160 battements par minute. La COTNO était mesurée avant et immédiatement après la séance d’exercice. La pression artérielle (PA) et la PIO étaient mesurées ponctuellement alors que le pouls et la saturation sanguine en oxygène (SpO2) au niveau digital étaient mesurés tout au long de l’expérience. L’effort physique a entrainé une réduction de la PIO chez tous les sujets, une réduction de la COTNO chez tous les sujets sauf un tandis que la SpO2 demeura constante chez tous les sujets. Une corrélation quadratique entre les variations de la PIO et de la COTNO a pu être notée. Ces résultats suggèrent une corrélation directe entre les variations de la COTNO et celles de la PPO et de la PA. Les résultats de la présente étude suggèrent que les variations de la COTNO chez un sujet en santé suite à un effort physique dynamique pourraient représenter sa capacité à compenser un tel effort. De plus, les changements métaboliques sanguins induits par l’effort physique dynamique pourraient représenter une cause commune aux variations de la PIO et de la COTNO. / It is generally accepted that ocular vascular beds have the ability to autoregulate their blood flow to counter balance the variations in the ocular perfusion pressure (OPP). Many studies have tried to evaluate this mechanism by quantifying the effects of a variation in OPP on the ocular blood flow (OBF). This was induced by either exercise or scleral suction which increases intra-ocular pressure (IOP). However, the methods used for these measurements have many disadvantages and limitations, which deters their clinical use. Recent developments in the field of non-invasive investigation of ocular blood parameters propose a model for the measurement, in real-time, of oxygen concentration in the blood streams, another important parameter of the retinal metabolism. In the present study, this new model is used to evaluate the effects of dynamic physical efforts on the blood oxygenation in the optic nerve head capillary structures (BOONH) in young healthy subjects. Six non-smoking young men participated in the study. 15-minute sessions of stationary bicycle leading to a heart rate of 160bpm were performed as dynamic physical effort. The BOONH was measured before and immediately after the exercise. The blood pressure (BP) and the IOP were measured periodically while the heart rate and the oxygen saturation in blood (SpO2) were measured in a finger throughout the exercise. The physical effort led to a reduction of the IOP in all subjects, a decrease in the BOONH in all but one subjects and a constant SpO2 in all subjects. A quadratic correlation was observed between the variations in IOP and in BOONH. These results suggest a direct correlation between the variations in BOONH and those of the OPP and the BP. The results of the present study suggest that the variations in BOONH in a healthy subject following a physical dynamic effort could indicate his/her capacity to compensate for such an effort. Moreover, the metabolic changes in the blood due to physical dynamic efforts could be a common cause of the variations in IOP and BOONH.

Il est généralement accepté que les lits vasculaires oculaires auraient la faculté d’autoréguler leur apport sanguin afin de contrebalancer les variations de pression de perfusion oculaire (PPO). Plusieurs études ont tenté d’évaluer ce mécanisme en mesurant les effets d’une variation de la PPO - induite par un exercice ou par une augmentation de la pression intra-oculaire (PIO) à l’aide d’une suction sclérale - sur le débit sanguin oculaire (DSO). Or, les méthodes de mesure du DSO utilisées jusqu'à maintenant présentent de nombreux désavantages et limites, ce qui rend difficile leur usage clinique. De récents développements dans le domaine des investigations non-invasives des paramètres sanguins oculaires proposent un modèle capable de mesurer en temps réel la concentration en oxygène, un autre paramètre important du métabolisme rétinien. Dans le cadre de la présente étude, ce nouveau modèle est utilisé afin de mesurer les effets d’un effort physique dynamique sur la concentration d’oxygène dans les capillaires de la tête du nerf optique (COTNO) de sujets jeunes et en santé. Six jeunes hommes non fumeurs ont participé à l’étude. L’effort physique dynamique consistait en une séance de bicyclette stationnaire de 15 minutes menant à une augmentation du pouls à 160 battements par minute. La COTNO était mesurée avant et immédiatement après la séance d’exercice. La pression artérielle (PA) et la PIO étaient mesurées ponctuellement alors que le pouls et la saturation sanguine en oxygène (SpO2) au niveau digital étaient mesurés tout au long de l’expérience. L’effort physique a entrainé une réduction de la PIO chez tous les sujets, une réduction de la COTNO chez tous les sujets sauf un tandis que la SpO2 demeura constante chez tous les sujets. Une corrélation quadratique entre les variations de la PIO et de la COTNO a pu être notée. Ces résultats suggèrent une corrélation directe entre les variations de la COTNO et celles de la PPO et de la PA. Les résultats de la présente étude suggèrent que les variations de la COTNO chez un sujet en santé suite à un effort physique dynamique pourraient représenter sa capacité à compenser un tel effort. De plus, les changements métaboliques sanguins induits par l’effort physique dynamique pourraient représenter une cause commune aux variations de la PIO et de la COTNO. / It is generally accepted that ocular vascular beds have the ability to autoregulate their blood flow to counter balance the variations in the ocular perfusion pressure (OPP). Many studies have tried to evaluate this mechanism by quantifying the effects of a variation in OPP on the ocular blood flow (OBF). This was induced by either exercise or scleral suction which increases intra-ocular pressure (IOP). However, the methods used for these measurements have many disadvantages and limitations, which deters their clinical use. Recent developments in the field of non-invasive investigation of ocular blood parameters propose a model for the measurement, in real-time, of oxygen concentration in the blood streams, another important parameter of the retinal metabolism. In the present study, this new model is used to evaluate the effects of dynamic physical efforts on the blood oxygenation in the optic nerve head capillary structures (BOONH) in young healthy subjects. Six non-smoking young men participated in the study. 15-minute sessions of stationary bicycle leading to a heart rate of 160bpm were performed as dynamic physical effort. The BOONH was measured before and immediately after the exercise. The blood pressure (BP) and the IOP were measured periodically while the heart rate and the oxygen saturation in blood (SpO2) were measured in a finger throughout the exercise. The physical effort led to a reduction of the IOP in all subjects, a decrease in the BOONH in all but one subjects and a constant SpO2 in all subjects. A quadratic correlation was observed between the variations in IOP and in BOONH. These results suggest a direct correlation between the variations in BOONH and those of the OPP and the BP. The results of the present study suggest that the variations in BOONH in a healthy subject following a physical dynamic effort could indicate his/her capacity to compensate for such an effort. Moreover, the metabolic changes in the blood due to physical dynamic efforts could be a common cause of the variations in IOP and BOONH.

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.

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.

Le glaucome est la première cause de cécité irréversible dans le monde. Bien que sa pathogenèse demeure encore nébuleuse, les propriétés biomécaniques de l’oeil sembleraient jouer un rôle important dans le développement et la progression de cette maladie. Il est stipulé que la rigidité oculaire (RO) est altérée au travers les divers stades de la maladie et qu’elle serait le facteur le plus influent sur la réponse du nerf optique aux variations de la pression intraoculaire (PIO) au sein du glaucome. Pour permettre l’investigation du rôle de la RO dans le glaucome primaire à angle ouvert (GPAO), la capacité de quantifier la RO in vivo par l’entremise d’une méthode fiable et non-invasive est essentielle. Une telle méthode n’est disponible que depuis 2015. Basée sur l'équation de Friedenwald, cette approche combine l'imagerie par tomographie par cohérence optique (TCO) et la segmentation choroïdienne automatisée afin de mesurer le changement de volume choroïdien pulsatile (ΔV), ainsi que la tonométrie dynamique de contour Pascal pour mesurer le changement de pression pulsatile correspondant. L’objectif de cette thèse est d’évaluer la validité de cette méthode, et d’en faire usage afin d’investiguer le rôle de la RO dans les maladies oculaires, particulièrement le GPAO. Plus spécifiquement, cette thèse vise à : 1) améliorer la méthode proposée et évaluer sa validité ainsi que sa répétabilité, 2) investiguer l’association entre la RO et le dommage neuro-rétinien chez les patients glaucomateux, et ceux atteints d’un syndrome de vasospasticité, 3) évaluer l’association entre la RO et les paramètres biomécaniques de la cornée, 4) évaluer l’association entre la RO et les pics de PIO survenant suite aux thérapies par injections intravitréennes (IIV), afin de les prédire et de les prévenir chez les patients à haut risque, et 5) confirmer que la RO est réduite dans les yeux myopes. D’abord, nous avons amélioré le modèle mathématique de l’oeil utilisé pour dériver ΔV en le rendant plus précis anatomiquement et en tenant compte de la choroïde périphérique. Nous avons démontré la validité et la bonne répétabilité de cette méthodologie. Puis, nous avons effectué la mesure des coefficients de RO sur un large éventail de sujets sains et glaucomateux en utilisant notre méthode non-invasive, et avons démontré, pour la première fois, qu'une RO basse est corrélée aux dommages glaucomateux. Les corrélations observées étaient comparables à celles obtenues avec des facteurs de risque reconnus tels que la PIO maximale. Une forte corrélation entre la RO et les dommages neuro-rétiniens a été observée chez les patients vasospastiques, mais pas chez ceux atteints d'une maladie vasculaire ischémique. Cela pourrait potentiellement indiquer une plus grande susceptibilité au glaucome due à la biomécanique oculaire chez les patients vasospastiques. Bien que les paramètres biomécaniques cornéens aient été largement adoptés dans la pratique clinique en tant que substitut pour la RO, propriété biomécanique globale de l'oeil, nous avons démontré une association limitée entre la RO et ces paramètres, offrant une nouvelle perspective sur la relation entre les propriétés biomécaniques cornéennes et globales de l’oeil. Seule une faible corrélation entre le facteur de résistance cornéenne et la RO demeure après ajustement pour les facteurs de confusion dans le groupe des patients glaucomateux. Ensuite, nous avons présenté un modèle pour prédire l'amplitude des pics de PIO après IIV à partir de la mesure non-invasive de la RO. Ceci est particulièrement utile pour les patients à haut risque atteints de maladies rétiniennes exsudatives et de glaucome qui nécessiteraient des IIV thérapeutiques, et pourrait permettre aux cliniciens d'ajuster ou de personnaliser le traitement pour éviter toute perte de vision additionnelle. Enfin, nous avons étudié les différences de RO entre les yeux myopes et les non-myopes en utilisant cette technique, et avons démontré une RO inférieure dans la myopie axiale, facteur de risque du GPAO. Dans l'ensemble, ces résultats contribuent à l’avancement des connaissances sur la physiopathologie du GPAO. Le développement de notre méthode permettra non seulement de mieux explorer le rôle de la RO dans les maladies oculaires, mais contribuera également à élucider les mécanismes et développer de nouveaux traitements ciblant la RO pour contrer la déficience visuelle liée à ces maladies. / Glaucoma is the leading cause of irreversible blindness worldwide. While its pathogenesis is yet to be fully understood, the biomechanical properties of the eye are thought to be involved in the development and progression of this disease. Ocular rigidity (OR) is thought to be altered through disease processes and has been suggested to be the most influential factor on the optic nerve head’s response to variations in intraocular pressure (IOP) in glaucoma. To further investigate the role of OR in open-angle glaucoma (OAG) and other ocular diseases such as myopia, the ability to quantify OR in living human eyes using a reliable and non-invasive method is essential. Such a method has only become available in 2015. Based on the Friedenwald equation, the method uses time-lapse optical coherence tomography (OCT) imaging and automated choroidal segmentation to measure the pulsatile choroidal volume change (ΔV), and Pascal dynamic contour tonometry to measure the corresponding pulsatile pressure change. The purpose of this thesis work was to assess the validity of the methodology, then use it to investigate the role of OR in ocular diseases, particularly in OAG. More specifically, the objectives were: 1) To improve the extrapolation of ΔV and evaluate the method’s validity and repeatability, 2) To investigate the association between OR and neuro-retinal damage in glaucomatous patients, as well as those with concomitant vasospasticity, 3) To evaluate the association between OR and corneal biomechanical parameters, 4) To assess the association between OR and IOP spikes following therapeutic intravitreal injections (IVIs), to predict and prevent them in high-risk patients, and 5) To confirm that OR is lower in myopia. First, we improved the mathematical model of the eye used to derive ΔV by rendering it more anatomically accurate and accounting for the peripheral choroid. We also confirmed the validity and good repeatability of the method. We carried out the measurement of OR coefficients on a wide range of healthy and glaucomatous subjects using this non-invasive method, and were able to show, for the first time, that lower OR is correlated with more glaucomatous damage. The correlations observed were comparable to those obtained with recognized risk factors such as maximum IOP. A strong correlation between OR and neuro-retinal damage was found in patients with concurrent vasospastic syndrome, but not in those with ischemic vascular disease. This could perhaps indicate a greater susceptibility to glaucoma due to ocular biomechanics in vasospastic patients. While corneal biomechanical parameters have been widely adopted in clinical practice as surrogate measurements for the eye’s overall biomechanical properties represented by OR, we have shown a limited association between these parameters, bringing new insight unto the relationship between corneal and global biomechanical properties. Only a weak correlation between the corneal resistance factor and OR remained in glaucomatous eyes after adjusting for confounding factors. In addition, we presented a model to predict the magnitude of IOP spikes following IVIs from the non-invasive measurement of OR. This is particularly useful for high-risk patients with exudative retinal diseases and glaucoma that require therapeutic IVIs, and could provide the clinician an opportunity to adjust or customize treatment to prevent further vision loss. Finally, we investigated OR differences between non-myopic and myopic eyes using this technique, and demonstrated lower OR in axial myopia, a risk factor for OAG. Overall, these findings provide new insights unto the pathophysiology of glaucomatous optic neuropathy. The development of our method will permit further investigation of the role of OR in ocular diseases, contributing to elucidate mechanisms and provide novel management options to counter vision impairment caused by these diseases.

Purpose To evaluate the effectiveness and safety of Selective Laser Trabeculoplasty (SLT) with the SLT mode of the VISULAS ® green laser in patients with primary open-angle glaucoma (POAG). Methods This prospective, interventional multicenter clinical investigation included patients with POAG who either needed a treatment escalation because the individual intraocular pressure (IOP) target was not met or treatment initiation and had an IOP ≥ 17 mmHg at baseline in the study eye. The study was conducted in five research centers across Germany. Approximately 100 laser applications were delivered to 360° of the trabecular meshwork. Glaucoma medications were not modified during the 3-month follow-up to allow evaluation of the sole effect of VISULAS ® green with SLT. Efficacy outcomes were postoperatively absolute and relative IOP changes at 1 and 3 months. Safety outcomes analyzed the rate of intra- and postoperative adverse events. Results Thirty-four eyes of 34 POAG patients were included. The overall mean number of preoperative glaucoma medications was 2.2 ± 1.4 in 29 treated eyes, 5 eyes were treatment naïve. Mean baseline IOP (mmHg) was 21.0 ± 2.69 and was reduced by − 3.53 ± 3.34 [95% CI − 4.61; − 2.45] and − 3.59 ± 3.41 [95% CI − 4.64; − 2.53] at the 1- and 3-month follow-up, respectively (p < 0.0001), with 48.5% of cases achieving a ≥ 20% IOP reduction at 3 months [95% CI = 30.8%; 66.5%]. The mean relative IOP reduction was − 16.4% and − 16.3% at 1 and 3 months, respectively (p < 0.0001). Potentially device- or procedure-related adverse events were mild to moderate and included 3 postoperative IOP-spikes and 6 reports regarding eye pain and discomfort. All were resolved without sequelae. Conclusions SLT performed with the VISULAS ® green laser achieved clinically significant additional IOP reductions in medically treated as well as in treatment naïve eyes with POAG and there were no relevant safety issues. The results are comparable to other reported SLT studies.