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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.
241

Enhanced Objective Detection of Retinal Nerve Fiber Bundle Defects in Glaucoma With a Novel Method for En Face OCT Slab Image Construction and Analysis

Cheloni, R., Dewsbery, S.D., Denniss, Jonathan 11 October 2021 (has links)
Yes / To introduce and evaluate the performance in detecting glaucomatous abnormalities of a novel method for extracting en face slab images (SMAS), which considers varying individual anatomy and configuration of retinal nerve fiber bundles. Dense central retinal spectral domain optical coherence tomography scans were acquired in 16 participants with glaucoma and 19 age-similar controls. Slab images were generated by averaging reflectivity over different depths below the inner limiting membrane according to several methods. SMAS considered multiple 16 µm thick slabs from 8 to 116 µm below the inner limiting membrane, whereas 5 alternative methods considered single summary slabs of various thicknesses and depths. Superpixels in eyes with glaucoma were considered abnormal if below the first percentile of distributions fitted to control data for each method. The ability to detect glaucoma defects was measured by the proportion of abnormal superpixels. Proportion of superpixels below the fitted first percentile in controls was used as a surrogate false-positive rate. The effects of slab methods on performance measures were evaluated with linear mixed models. The ability to detect glaucoma defects varied between slab methods, χ2(5) = 120.9, P
242

Concordance of objectively-detected retinal nerve fiber bundle defects in en face OCT images with conventional structural and functional changes in glaucoma.

Cheloni, Riccardo, Denniss, Jonathan 15 September 2022 (has links)
Yes / To assess how objectively-detected defects of retinal nerve fibre bundle (RNFB) reflectance in en face OCT images relate to circumpapillary retinal nerve fibre layer thickness (cpRNFLT) and visual field defects. Cross-sectional study. 16 participants with early-glaucoma and 29 age-similar healthy controls, among which 22 had usable en face images to establish normative levels of RNFB reflectance. All participants underwent cpRNFLT scans, visual field examination and wide-field OCT. En face reflectivity was assessed objectively using the Summary of Multiple Anatomically-Adjusted Slabs (SMAS) method. En face defects were deemed concordant with cpRNFLT when they had at least one cpRNFLT point with p
243

Fine-tuned convolutional neural networks for improved glaucoma prediction

Smedjegård, Filip January 2024 (has links)
Early detection is crucial for effectively treating glaucoma, a leading cause of irreversible blindness. Diagnosing glaucoma can be challenging due to its subtle early symptoms. This study aims to enhance glaucoma prediction by fine-tuning pre-trained convolutional neural networks. Several networks were re-trained and tested on publicly available retinal image datasets. Additionally, the models were evaluated on fundus images from patients at Region Västernorrland (RVN). The methodology involved exploring how to effectively process and prepare patient data for prediction purposes. The results showed that a majority voting ensemble of the fine-tuned models produced the highest performance, achieving an accuracy of approximately 0.94, with a specificity and sensitivity of 0.97 and 0.90 respectively. The ensemble also identified 0.90 glaucomatous images from RVN correctly. In terms of specificity and sensitivity, all models outperformed the results of ophthalmologist specialists described in a previous study. The findings suggest the effectiveness of transfer learning in enhancing the diagnostic accuracy of glaucoma. It also underscores the importance of proper storage and preparation of medical data for developing predicitive machine learning models. / Glaukom, mer känt som grön starr, är en av de vanligast förekommande ögonsjukdomarna som orsakar blindhet. Det är viktigt att diagnostisera glaukom tidigt i sjukdomsförloppet för att genom behandling, sakta ner eller stoppa ytterligare synförlust. Att diagnostisera glaukom kan vara utmanande, eftersom det vanligtvis inte visar några tidiga symtom. Artificiell intelligens (AI), eller mer specifikt maskininlärning (ML), kan hjälpa läkare att ställa rätt diagnos om det används som ett beslutsstöd. Faltande neurala nätverk (convolutional neural network, CNN) kan lära sig att känna igen mönster i bilder, för att därigenom klassificera bilder till olika kategorier. Ett sätt att diagnostisera glaukom är att studera näthinnan och synnerven i ögats bakre del, som kallas ögonbotten. I denna studie finjusterades redan tränade CNN:s för att prediktera glaukom utifrån ögonbottenbilder. Detta uppnåddes genom att träna om modellerna på publikt tillgängliga ögonbottenbilder. Målet var att jämföra nätverkens noggrannhet på en delmängd av bilderna, samt att evaluera dem på ögonbottenbilder från sjukhus i Region Västernorrland (RVN). För att uppnå detta ingick det även i metodiken att utforska begränsningarna och möjligheterna med hur patientdata får användas, samt att undersöka hur datat bör lagras och tillrättaläggas för att möjliggöra utvecklingen av prediktionsmodeller. Syftet med studien var att öka noggrannheten vid diagnostisering av glaukom. Resultaten visade att en ensemble baserad på majoritetsröstning av alla modeller gav den bästa noggrannheten, ungefär 0.94. Sensitiviteten och specificiteten var 0.90, respektive 0.97. Vidare klassificerades 90% av ögonbottenbilderna från RVN korrekt. Resultaten tyder på att maskininlärning är effektivt för att förbättra den diagnostiska noggrannheten för glaukom. Det understryker också vikten av strategisk lagring och förberedelse av medicinska data för att utveckla prediktiva maskininlärningsmodeller i framtiden.
244

Assessment of knowledge about glaucoma amongst patients attending an eye clinic in Abuja, Nigeria

Onunkwur, Christopher Ifeanyi 11 1900 (has links)
The purpose of the study was to assess the level of knowledge about glaucoma among the patients who attend the CBN staff eye clinic in Abuja. An exploratory, descriptive and cross-sectional study was conducted on adult CBN staff members and their eligible dependants. Data on demographics and knowledge of glaucoma were collected using a pre-tested structured questionnaire. One hundred and forty five respondents (100% return) participated in the study. Purposive sampling was done to recruit respondents. Of the total respondents’, 74.5% (n=108) claimed they had heard about glaucoma but only 14.5% (n = 21) had knowledge about glaucoma. Glaucoma knowledge was found to be independent of age, sex, ethnicity, educational level and respondents’ status within the CBN. Knowledge about glaucoma in this population is therefore according to the results, inadequate. Appropriate recommendations were made to improve glaucoma knowledge amongst patients who attend the clinic. / Health Studies
245

Influência da exérese da cápsula de Tenon na cirurgia de implante de Ahmed com uso da mitomicina C em portadores de glaucoma neovascular / Partial Tenon´s capsule resection with adjunctive mitomycin C in Ahmed valve implant surgery among neovascular glaucoma patients

Giampani Junior, Jair 15 October 2004 (has links)
Este estudo teve por objetivo avaliar a eficácia e a segurança da cirurgia de implante de Ahmed, associada à ressecção parcial da cápsula de Tenon e ao uso da mitomicina C, em portadores de glaucoma neovascular. A amostra foi constituída por 31 olhos de trinta pacientes portadores de glaucoma neovascular, secundário à retinopatia diabética proliferativa ou à oclusão da veia central da retina, com acuidade visual maior ou igual à percepção luminosa. Os olhos foram randomizados para formarem dois grupos: implante de Ahmed convencional, associado ao uso da mitomicina C (n=15), e implante de Ahmed de alta resistência, associado à ressecção parcial da cápsula de Tenon e ao uso da mitomicina C (n=16). Controlaram-se as variáveis procurando homogeneizar os grupos a fim de prevenir vieses nas avaliações dos desfechos. Definiram-se como sucesso cirúrgico simples os casos com pressões oculares maiores ou iguais a 5 mm Hg e menores ou iguais a 21 mm Hg. A média de idade foi de 58,06 anos ± 13,02 , sendo de 62,63 anos ± 10,23 no grupo com e de 53,20 anos ± 14,22 no grupo sem ressecção parcial da cápsula de Tenon (p = 0,109). Não houve diferença estatisticamente significativa entre os grupos com relação ao sexo (p = 0,722), olho operado (p = 1,0), causa do glaucoma neovascular (p = 1,0), existência de panfotocoagulação prévia (p = 1,0) e acuidade visual pré-operatória (p = 0,154). A pressão ocular média pré-operatória foi de 51,00 ± 10,05 mm Hg no grupo com ressecção parcial da cápsula de Tenon e de 51,20 ± 11,58 mm Hg no grupo sem ressecção da cápsula de Tenon (p = 0,889). Houve redução significativa da pressão ocular em ambos os grupos a partir do primeiro dia do pós-operatório. A pressão ocular média dos grupos com e sem ressecção parcial da cápsula de Tenon aos 24 meses de seguimento foi de, respectivamente, 17,00 ± 12,77 mm Hg e 19,78 ± 15,71 mm Hg (p = 0,820). O seguimento médio foi de 23,44 meses ± 9,63 no grupo com ressecção parcial da cápsula de Tenon e de 23,40 meses ± 9,62 no grupo sem ressecção parcial da cápsula de Tenon (p = 0,952). Registraram-se diferenças estatisticamente significativas entre as pressões médias nos grupos com e sem ressecção parcial da cápsula de Tenon apenas no primeiro dia, terceiro e sétimo meses do pós-operatório. Houve redução mais intensa da acuidade visual no grupo sem ressecção parcial da cápsula de Tenon do que no grupo com exérese da cápsula de Tenon (p = 0,023*). O sucesso simples foi de 62,5% (dez olhos) no grupo com e de 53,3% (oito olhos) no grupo sem ressecção parcial da cápsula de Tenon (p = 0,722). Não se verificaram bolhas transparentes, pálidas ou isquêmicas em fase alguma do pós-operatório, em ambos os grupos. As freqüências das complicações foram semelhantes em ambos os grupos, exceto por uma freqüência quase quatro vezes maior de exposição do implante no grupo com ressecção parcial da cápsula de Tenon. Em resumo, os índices de sucesso cirúrgico foram semelhantes entre os grupos com e sem ressecção parcial da cápsula de Tenon, após um seguimento médio de 23,42 meses. Houve redução significativa da acuidade visual nos dois grupos, a qual foi mais intensa naquele sem ressecção parcial da cápsula de Tenon. A exposição do implante de drenagem foi quase quatro vezes mais freqüente no grupo submetido à ressecção parcial da cápsula de Tenon / The objective of the study was to evaluate the safety and efficacy of Ahmed glaucoma valve implant surgery combined with partial Tenon\'s capsule resection and mitomycin C administration in neovascular glaucoma patients. Our sample comprised 31 eyes of 30 patients with neovascular glaucoma secondary to proliferative diabetic retinopathy or central retinal vein occlusion. The 30 patients all had visual acuity equal to or greater than their perception of light. The eyes were randomized into two groups: conventional Ahmed valve implant combined with mitomycin C administration (n = 15); and high-resistance Ahmed implant combined with partial Tenon\'s capsule resection and mitomycin C administration (n = 16). Variables were controlled in an attempt to homogenize the groups and thereby avoid any bias in the evaluation of the results. Simple surgical success was defined as ocular pressure equal to or greater than 5 mmHg but less than or equal to 21 mmHg. Median age was 58.06 ± 13.02 (53.20 ± 14.22 in the group not submitted to resection and 62.63 ± 10.23 in the group submitted to partial Tenon\'s capsule resection; p = 0.109). No statistically significant difference between the groups was found related to gender (p = 0.722), operated eye (p = 1.0), cause of neovascular glaucoma (p = 1.0), previous panphotocoagulation (p = 1.0), or preoperative visual acuity (p = 0.154). Mean preoperative ocular pressure was 51.20 ± 11.58 mmHg in the group not submitted to resection and 51 ± 10.05 mmHg in the group submitted to partial Tenon\'s capsule resection (p = 0.889). From the first preoperative day, there was a significant reduction in ocular pressure in both groups. At 24 months after surgery, mean ocular pressure of subjects not submitted and submitted to partial Tenon\'s capsule resection was 19.78 ± 15.71 mmHg and 17.00 ± 12.77 mmHg, respectively (p = 0.820). Mean length of the follow-up period was 23.40 ± 9.62 months in those not submitted to resection and 23.44 ± 9.63 months in the group submitted to partial Tenon\'s capsule resection (p = 0.952). Statistically significant differences in ocular pressure were found between the two groups only on postoperative day 1 and at 3 and 7 months after surgery. In the group not submitted to resection, there was a more marked reduction in visual acuity (p = 0.023*). Simple surgical success was achieved in 53.3% (8) of the eyes in the group not submitted to resection and in 62.5% (10) of the eyes in the group submitted to partial Tenon\'s capsule resection (p = 0.722). There were no pale or transparent blebs in either group during the postoperative phase. The incidence of complications was similar between the two groups, with the exception of the incidence of implant tube exposure, which was four times greater in the group submitted to partial Tenon\'s capsule resection. In conclusion, after a mean follow-up period of 23.42 months, the measures of surgical success were comparable between the two groups. There was significant reduction in visual acuity in both groups, more markedly in the group not submitted to resection. The implant drainage tube became exposed four times more frequently in the group submitted to partial Tenon\'s capsule resection
246

Applications of optical coherence tomography imaging in the assessment of glaucoma. / CUHK electronic theses & dissertations collection

January 2006 (has links)
Although the current OCT imaging system was designed to examine the retinal structures, a novel application in imaging the anterior chamber angle was studied in section 3.7. OCT was demonstrated to be clinically useful for visualization of the different patterns of angle configurations in different forms of angle closure glaucoma. / In section 3.5, RNFL measurement by OCT was cross-validated by another nerve fiber analyzer, scanning laser polarimetry (SLP). While both OCT and SLP demonstrated comparable diagnostic performance for glaucoma detection and high correlation in the respective RNFL measurements, OCT was found to provide a closer estimation of RNFL thickness with reference to the reported histological measurements. In section 3.6, the structural-functional relationship between RNFL thickness and visual sensitivity was evaluated and compared between OCT and SLP. The relationships were found to be dependent on the choice of the perimetry scale, the type of RNFL measuring devices and the characteristics of the studied subjects. It was concluded that regression analysis of the structural-functional profile could provide important information in the assessment of the trend and pattern of glaucoma progression. / In summary, optical coherence tomography was shown to be useful in the diagnosis of glaucoma and in the evaluation of the trend and pattern of disease progression. / Objectives. The research project was designed to investigate the applications of optical coherence tomography in the assessment of glaucoma. The goals are to identify sensitive and specific anatomic markers, and analytical method for detection of glaucomatous changes, to evaluate the intricate structural-functional relationships in glaucoma with regression analysis and to assess the potential application of optical coherence tomography imaging system in visualization of the anterior chamber angle with a view to obtain OCT data to help understanding the pathophysiology of different forms of angle-closure glaucoma. / Sections 3.1 to 3.3 were designed to identify the most sensitive and specific diagnostic marker(s) for glaucoma detection. Peripapillary retinal nerve fiber layer (RNFL), macular thickness, optic nerve head parameters measured with different reference planes, and a novel anatomic marker - macular nerve fiber layer were investigated. The averaged peripapillary RNFL thickness measured with a high resolution scan (512 scan point) was found to have the best discriminating power for detection of glaucoma. It also has the strongest correlation with visual function. To examine if utilization of the complete data profile of peripapillary RNFL could further improve diagnostic sensitivity, a novel approach with the use of neural network trained to recognize RNFL pattern was studied in section 3.4. It was concluded that neural network analysis could enhance the diagnostic performance for glaucoma detection. / Summary. Glaucoma is a progressive optic neuropathy characterized by the loss of retinal ganglion cells resulting in constriction of visual field and loss of vision as the disease progresses. Since structural damage in glaucoma occurs well before any detectable loss in visual function, clinical examination of the optic nerve head and its nerve fiber layer is crucial in establishing the diagnosis, monitoring the progression and initiating treatment before irreversible damage takes place. The present research project is composed of 7 coherent studies (sections 3.1 to 3.7), aiming to investigate the clinical applications of optical coherence tomography (OCT), an advanced imaging device for detailed examination of optic nerve head and nerve fiber layer, in the assessment of glaucoma. / Leung Kai-shun. / "June 2006." / Adviser: Chi Pui Pang. / Source: Dissertation Abstracts International, Volume: 67-11, Section: B, page: 6323. / Thesis (M.D.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references (p. 212-227). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / School code: 1307.
247

Assessment of glaucoma progression using digital imaging technologies / CUHK electronic theses & dissertations collection

January 2015 (has links)
Glaucoma is characterized by progressive optic nerve head (ONH) deformation and retinal nerve fiber layer (RNFL) thinning but the relative sequence of ONH and RNFL changes in glaucoma remains largely uncertain. It has been proposed that structural damage of the optic nerve can often be detected before detectable functional loss. Therefore, investigating structural changes of the ONH and RNFL is of importance and relevance in the monitoring and management of glaucoma progression. Spectral domain optical coherence tomography (OCT), scanning laser polarimetry (SLP) and confocal scanning laser ophthalmoscopy (CSLO) are the three prevailing digital imaging technologies for measurement of RNFL thickness, RNFL retardance and ONH parameters, respectively. Although these instruments have been extensively investigated for detection of glaucomatous damage, less is known about their relative performance for detection of change in glaucoma progression. Although previous studies on non- human primates showed that disruption of the microtubule structure of the retinal ganglion cell axons detected by SLP as reduction of RNFL retardance, as well as ONH surface deformation detected by CSLO, could be detected prior to reduction of RNFL thickness measured with OCT, clinical data corroborating this observation are lacking. The sequence of change of RNFL thickness, RNFL retardance and ONH parameters has not been investigated in human glaucoma. / This research project aimed to investigate the performance of OCT, SLP and CLSO for change detection of RNFL and ONH damages, determine the relative sequence of change of RNFL retardance and RNFL thickness and ONH deformation, and evaluate if ocular biomechanical properties, measured as corneal hysteresis by the ocular response analyzer (ORA, Reichert Inc.), influence the detection of ONH and RNFL progression in glaucoma patients. We hypothesized that ONH deformation and loss of RNFL retardance could be detected before detectable RNFL thinning and that the baseline corneal hysteresis would be a risk factor for ONH and RNFL damage in glaucoma. / In the first study, we analyzed 184 eyes of 116 patients with glaucoma and 43 normal eyes of 23 healthy individuals followed for a mean of 4.6 years. All subjects had RNFL retardance and RNFL thickness measurements obtained with GDx ECC (Carl Zeiss Meditec) and Cirrus HD-OCT (Carl Zeiss Meditec), respectively, at 4-month intervals. Progressive reduction of RNFL retardance and RNFL thickness were evaluated with Guided Progression Analysis (GPA, Carl Zeiss Meditec) with reference to the RNFL retardance change map and RNFL thickness change map, respectively. Twenty seven eyes of 26 patients showed progressive RNFL thinning whereas 8 eyes of 8 patients had RNFL retardance reduction in the latest follow-up visit. Seven eyes of 7 patients had progressive RNFL thinning and reduction of RNFL retardance detected by both instruments; all had progressive RNFL thinning evident before reduction of RNFL retardance and the mean lag time was 13.4 months (range: 4.0-37.6 months). The survival time of eyes detected with RNFL thinning was significantly shorter than the survival time of eyes detected with reduction of RNFL retardance (P=0.001). No eyes in the normal group showed progressive RNFL changes during follow-up. Collectively, we showed that at a comparable specificity (100%, 95% confidence interval: 96.3%-100%), progressive RNFL thinning was detected more often than progressive reduction of RNFL retardance and the former preceded the latter in eyes with both progressive RNFL thinning and reduction of RNFL retardance. / In the second study using a similar study design, we investigated the sequence of change of ONH surface depression detected by CSLO (HRT 3, Heidelberg Engineering) and RNFL thinning detected by OCT (Cirrus HD-OCT, Carl Zeiss Meditec) in 146 eyes of 90 glaucoma patients followed at approximately 4-month intervals for an average of 5.4 years. Significant ONH surface depression and RNFL thinning were defined with reference to Topographic Change Analysis (TCA, Heidelberg Engineering) and Guided Progression Analysis (GPA, Carl Zeiss Meditec), respectively. At a specificity of 94.3% (95% confidence interval: 86.2%-97.8%) for both RNFL thinning and ONH surface depression (determined in a normal group comprising 70 eyes from 35 normal subjects), 57 eyes (39.0%) had ONH surface depression, 46 eyes (31.5%) had RNFL thinning, and 23 eyes (15.8%) had both in the glaucoma group. Among these 23 eyes, 19 (82.6%) had ONH surface depression detected prior to RNFL thinning and the median lag time was 15.8 months (range, 4.0-40.8 months). Although only 7.0% of eyes (4/57) had RNFL thinning at the onset of ONH surface depression, 45.7% (21/46) had ONH surface depression at the onset of RNFL thinning. The survival time of eyes with ONH surface depression was significantly shorter than the survival time of eyes detected with RNFL thinning (P=0.002). With reference to the HRT TCA and OCT GPA, ONH surface depression occurred before RNFL thinning in a significant proportion of patients with glaucoma at a comparable specificity. / Of note, a significant proportion of eyes had ONH surface depression without any detectable progressive RNFL thinning in the second study, and vice versa. Investigating whether the risk factors for ONH surface depression and RNFL progression are different is therefore important. In the final study, we investigated if baseline corneal hysteresis is a risk factor for progressive ONH surface depression and RNFL thinning. Following the same cohort of 146 eyes of 90 glaucoma patients for an average of 6.8 years, we detected that 65 eyes (44.5%) had progressive ONH surface depression, 55 eyes (37.7%) had progressive RNFL thinning and 20 eyes (13.7%) had visual field progression (based on the EMGT criteria). After adjusting for ages, CCT, baseline diastolic IOP, average IOP during follow-up, baseline disc area and baseline MD in the cox proportional hazards model, baseline corneal hysteresis was significantly associated with ONH surface depression (HR=0.70, P=0.008), visual field progression (HR=0.56, P=0.019), but not with progressive RNFL thinning (HR=0.96, P=0.751). For each 1-mmHg decrease of baseline CH, the hazards for ONH surface depression and visual field progression increased by 30% and 44%, respectively. / In summary, at a comparable level of specificity, progressive ONH surface depression detected by CSLO could be observed prior to progressive RNFL thinning detected by OCT, which preceded identified reduction of RNFL retardance detected by SLP. For eyes with concomitant ONH surface depression, RNFL thinning and visual field progression, ONH surface depression always preceded visual field progression. Our finding indicates that a time window for therapeutic intervention may exist upon detection of ONH surface depression before irreversible RNFL and visual field loss and that measurement of CH would be useful to predict ONH surface depression and visual field progression. / Further studies are required to investigate the sequence of optic nerve head change and RNFL progression with the same instrument. Whether IOP lowering treatment initiated at the time of ONH deformation would be effective to prevent or slow down RNFL and visual field loss needs to be further investigated. A more reliable and accurate measure of the ocular biomechanical properties is necessary for evaluation of their contribution to glaucoma progression. / 青光眼是一種進展性視神經病變,其特徵為﹕視神經乳頭變形,神經纖維層(RNFL)的變薄以及相應的視野缺損。然而,青光眼結構性改變和功能性變化發生的相對順序仍不清楚。視神經結構性改變被認為要早於功能性改變的發生。因此,研究視乳頭的結構性改變具有重要意義,有助於早期診斷青光眼的進展及隨訪青光眼患者。目前主要用於RNFL厚度,RNFL阻滯性以及視乳頭參數的影像學掃描儀器為頻域OCT,鐳射偏振光掃描器(SLP)和共聚焦鐳射掃描眼底鏡(CSLO)。儘管這三種儀器已經廣泛用於青光眼損傷的檢測,但在青光眼患者結構性變化的應用並不常見。既往在非人靈長類動物的實驗中,通過破壞神經節細胞軸突中的微小管結構,從而發現RNFL的阻滯性以及視乳頭的變化要先於RNFL厚度變化的發生。然而在臨床研究中並未得到證實。同時,在青光眼患者中,RNFL厚度變化,RNFL阻滯減少以及視神經頭參數改變之間的先後順序並未得到證實。 / 本次實驗研究的目的在於探討OCT,SLP及CSLO在診斷青光眼病人RNFL及視乳頭進展的能力,確定RNFL厚度變化,RNFL阻滯性減少以及視神經頭參數改變之間的相對順序,以及評估眼反應分析儀(ORA)測得的角膜粘滯性(CH)是否影響視乳頭及RNFL厚度的進展。我們假設:視神經乳頭的變形,RNFL阻滯性的減少要先於RNFL厚度的變化,基線角膜粘滯性的測量會影響視乳頭及RNFL進展的檢測。116個青光眼病人的184隻眼以及23個正常對照的43隻眼被納入第一個研究中。所有受試物件均接受每4個月一次的OCT以及SLP RNFL的掃描,平均隨訪時間為4.6年。通過OCT及SLP中Guided Progression Analysis(GPA, Carl Zeiss Meditec)程式,一系列RNFL厚度及粘滯性圖被自動分析從而獲得RNFL厚度及粘滯性的變化結果。26個青光眼患者的27隻眼表現為RNFL厚度的進行性變薄,8個患者的8隻眼表現為RNFL粘滯性的減少。其中7個患者的7隻眼同時表現為RNFL厚度變薄及粘滯性的減少,所有這7隻眼的RNFL變薄的發生要早於RNFL粘滯性的減少,兩者間隔時間平均為13.4月(4.0-37.6月)。RNFL厚度變薄者的生存概率明顯小於RNFL粘滯性減少的青光眼患者(P=0.001)。隨訪中,我們未發現正常對照組中RNFL厚度變薄或者粘滯性改變者。總體說來,在同一特異性水準(100%),RNFL厚度的變化頻率高於粘滯性的改變,RNFL厚度的變薄要早於粘滯性減少的發生。 / 採用相同於第一個研究的研究方法,我們研究CSLO測得的視乳頭表面凹陷以及測得OCT的RNFL厚度變化發生的相對順序。90個青光眼患者的146隻眼以及35個正常對照物件的70隻眼被納入第二個研究中。所有受試物件均接受4個月一次的CSLO及OCT掃描從而獲得一系列的視神經頭表面的拓撲圖像以及RNFL厚度圖。CSLO TCA及OCT GPA程式自動對比基線及隨訪中所獲得的視神經頭表面的拓撲圖像以及RNFL厚度圖,從而獲得視乳頭表面凹陷及RFNL進展報告。平均隨訪5.4年後,CSLO及OCT在診斷視神經頭及RNFL進展的特異性為94.3%,57只青光眼患眼(39.0%)表現為顯著性視乳頭表面凹陷,46隻眼(31.5%)表現為RFNL厚度的進行性變薄,而23隻眼(15.8%)同時表現為視乳頭面凹陷和RFNL的進行性變薄。在這23只眼中,19隻眼(82.6%)變現為視乳頭表面凹陷先於RFNL厚度變薄的發生,間隔時間的中值為15.8個月(4.0-40.8月)。儘管在顯著性視乳頭表面凹陷發生時,僅有7.0%的患眼表現為RNFL厚度的變薄;但是,在RNFL厚度發生顯著性變薄時已有45.7%的患眼表現為視乳頭表面凹陷。視乳頭表面凹陷患眼的生存概率差於RNFL厚度變薄患眼(P=0.002)。在青光眼患者的隨訪中,CLSO TCA測得的視乳頭表面凹陷要早於OCT GPA測得的RNFL厚度的變化。 / 最後的一個研究目在於評估眼反應分析儀(ORA)測得的基線角膜粘滯性(CH)是否為視乳頭表面凹陷及RNFL厚度變薄的危險因素。平均隨訪同一人群即第二個研究中的90個青光眼患者的146眼6.8年,65隻眼(44.5%)被檢測出具有進行性視乳頭表面凹陷,55隻眼(37.7%)表現為進行性RNFL厚度的變薄,20隻眼(13.7%)表現為進行性視野的缺損(基於EMGT標準)。基線CH與視乳頭表面凹陷,視野進展間具有顯著性相關關係(HR=0.70,P=0.008及HR=0.56,P=0.019),但CH與進行性RNFL厚度變薄間並無顯著性相關關係(HR=0.96,P=0.751)。每1毫米汞柱基線CH的降低,發生視乳頭表面凹陷及視野缺損的危險性將增加30%及44%。CH的測量值與青光眼進展的危險性具有顯著相關關係。 / 總之,在具有可比性特異性水準下,CSLO檢測的進展性視乳頭表面凹陷的發生要先於OCT檢測的進行性RNFL厚度的變薄,後者的發生早於SLP測得的RNFL粘滯性的改變。對於同時有視乳頭表面凹陷,RNFL厚度變薄及RNFL粘滯性改變的青光眼患眼,視乳頭表面凹陷的發生要早於視野的進展。我們的實驗研究表明了在青光眼患者發生視乳頭表面凹陷時,治療的時間窗的存在有助於避免不可逆的RNFL缺失及視野的缺損。角膜粘滯性的測量對於預測視乳頭表面凹陷及視野進展具有重要意義。 / 展望未來的研究中,用同一種儀器進行視乳頭及神經纖維層的隨訪,從而得出相對的變化次序很有必要。研究在視乳頭或者神經纖維層發生變化時進行眼壓的干預是否能避免視功能的進一步損傷顯得尤為重要。用於測量角膜生物學特性的更為準確,可信度更高的儀器真正研發中,以及進一步探討角膜生物學特性與青光眼進展之間的關係。 / Xu, Guihua. / Thesis Ph.D. Chinese University of Hong Kong 2015. / Includes bibliographical references (leaves 116-145). / Abstracts also in Chinese. / Title from PDF title page (viewed on 18, October, 2016). / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only.
248

Assessment of knowledge about glaucoma amongst patients attending an eye clinic in Abuja, Nigeria

Onunkwur, Christopher Ifeanyi 11 1900 (has links)
The purpose of the study was to assess the level of knowledge about glaucoma among the patients who attend the CBN staff eye clinic in Abuja. An exploratory, descriptive and cross-sectional study was conducted on adult CBN staff members and their eligible dependants. Data on demographics and knowledge of glaucoma were collected using a pre-tested structured questionnaire. One hundred and forty five respondents (100% return) participated in the study. Purposive sampling was done to recruit respondents. Of the total respondents’, 74.5% (n=108) claimed they had heard about glaucoma but only 14.5% (n = 21) had knowledge about glaucoma. Glaucoma knowledge was found to be independent of age, sex, ethnicity, educational level and respondents’ status within the CBN. Knowledge about glaucoma in this population is therefore according to the results, inadequate. Appropriate recommendations were made to improve glaucoma knowledge amongst patients who attend the clinic. / Health Studies
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Influência da exérese da cápsula de Tenon na cirurgia de implante de Ahmed com uso da mitomicina C em portadores de glaucoma neovascular / Partial Tenon´s capsule resection with adjunctive mitomycin C in Ahmed valve implant surgery among neovascular glaucoma patients

Jair Giampani Junior 15 October 2004 (has links)
Este estudo teve por objetivo avaliar a eficácia e a segurança da cirurgia de implante de Ahmed, associada à ressecção parcial da cápsula de Tenon e ao uso da mitomicina C, em portadores de glaucoma neovascular. A amostra foi constituída por 31 olhos de trinta pacientes portadores de glaucoma neovascular, secundário à retinopatia diabética proliferativa ou à oclusão da veia central da retina, com acuidade visual maior ou igual à percepção luminosa. Os olhos foram randomizados para formarem dois grupos: implante de Ahmed convencional, associado ao uso da mitomicina C (n=15), e implante de Ahmed de alta resistência, associado à ressecção parcial da cápsula de Tenon e ao uso da mitomicina C (n=16). Controlaram-se as variáveis procurando homogeneizar os grupos a fim de prevenir vieses nas avaliações dos desfechos. Definiram-se como sucesso cirúrgico simples os casos com pressões oculares maiores ou iguais a 5 mm Hg e menores ou iguais a 21 mm Hg. A média de idade foi de 58,06 anos ± 13,02 , sendo de 62,63 anos ± 10,23 no grupo com e de 53,20 anos ± 14,22 no grupo sem ressecção parcial da cápsula de Tenon (p = 0,109). Não houve diferença estatisticamente significativa entre os grupos com relação ao sexo (p = 0,722), olho operado (p = 1,0), causa do glaucoma neovascular (p = 1,0), existência de panfotocoagulação prévia (p = 1,0) e acuidade visual pré-operatória (p = 0,154). A pressão ocular média pré-operatória foi de 51,00 ± 10,05 mm Hg no grupo com ressecção parcial da cápsula de Tenon e de 51,20 ± 11,58 mm Hg no grupo sem ressecção da cápsula de Tenon (p = 0,889). Houve redução significativa da pressão ocular em ambos os grupos a partir do primeiro dia do pós-operatório. A pressão ocular média dos grupos com e sem ressecção parcial da cápsula de Tenon aos 24 meses de seguimento foi de, respectivamente, 17,00 ± 12,77 mm Hg e 19,78 ± 15,71 mm Hg (p = 0,820). O seguimento médio foi de 23,44 meses ± 9,63 no grupo com ressecção parcial da cápsula de Tenon e de 23,40 meses ± 9,62 no grupo sem ressecção parcial da cápsula de Tenon (p = 0,952). Registraram-se diferenças estatisticamente significativas entre as pressões médias nos grupos com e sem ressecção parcial da cápsula de Tenon apenas no primeiro dia, terceiro e sétimo meses do pós-operatório. Houve redução mais intensa da acuidade visual no grupo sem ressecção parcial da cápsula de Tenon do que no grupo com exérese da cápsula de Tenon (p = 0,023*). O sucesso simples foi de 62,5% (dez olhos) no grupo com e de 53,3% (oito olhos) no grupo sem ressecção parcial da cápsula de Tenon (p = 0,722). Não se verificaram bolhas transparentes, pálidas ou isquêmicas em fase alguma do pós-operatório, em ambos os grupos. As freqüências das complicações foram semelhantes em ambos os grupos, exceto por uma freqüência quase quatro vezes maior de exposição do implante no grupo com ressecção parcial da cápsula de Tenon. Em resumo, os índices de sucesso cirúrgico foram semelhantes entre os grupos com e sem ressecção parcial da cápsula de Tenon, após um seguimento médio de 23,42 meses. Houve redução significativa da acuidade visual nos dois grupos, a qual foi mais intensa naquele sem ressecção parcial da cápsula de Tenon. A exposição do implante de drenagem foi quase quatro vezes mais freqüente no grupo submetido à ressecção parcial da cápsula de Tenon / The objective of the study was to evaluate the safety and efficacy of Ahmed glaucoma valve implant surgery combined with partial Tenon\'s capsule resection and mitomycin C administration in neovascular glaucoma patients. Our sample comprised 31 eyes of 30 patients with neovascular glaucoma secondary to proliferative diabetic retinopathy or central retinal vein occlusion. The 30 patients all had visual acuity equal to or greater than their perception of light. The eyes were randomized into two groups: conventional Ahmed valve implant combined with mitomycin C administration (n = 15); and high-resistance Ahmed implant combined with partial Tenon\'s capsule resection and mitomycin C administration (n = 16). Variables were controlled in an attempt to homogenize the groups and thereby avoid any bias in the evaluation of the results. Simple surgical success was defined as ocular pressure equal to or greater than 5 mmHg but less than or equal to 21 mmHg. Median age was 58.06 ± 13.02 (53.20 ± 14.22 in the group not submitted to resection and 62.63 ± 10.23 in the group submitted to partial Tenon\'s capsule resection; p = 0.109). No statistically significant difference between the groups was found related to gender (p = 0.722), operated eye (p = 1.0), cause of neovascular glaucoma (p = 1.0), previous panphotocoagulation (p = 1.0), or preoperative visual acuity (p = 0.154). Mean preoperative ocular pressure was 51.20 ± 11.58 mmHg in the group not submitted to resection and 51 ± 10.05 mmHg in the group submitted to partial Tenon\'s capsule resection (p = 0.889). From the first preoperative day, there was a significant reduction in ocular pressure in both groups. At 24 months after surgery, mean ocular pressure of subjects not submitted and submitted to partial Tenon\'s capsule resection was 19.78 ± 15.71 mmHg and 17.00 ± 12.77 mmHg, respectively (p = 0.820). Mean length of the follow-up period was 23.40 ± 9.62 months in those not submitted to resection and 23.44 ± 9.63 months in the group submitted to partial Tenon\'s capsule resection (p = 0.952). Statistically significant differences in ocular pressure were found between the two groups only on postoperative day 1 and at 3 and 7 months after surgery. In the group not submitted to resection, there was a more marked reduction in visual acuity (p = 0.023*). Simple surgical success was achieved in 53.3% (8) of the eyes in the group not submitted to resection and in 62.5% (10) of the eyes in the group submitted to partial Tenon\'s capsule resection (p = 0.722). There were no pale or transparent blebs in either group during the postoperative phase. The incidence of complications was similar between the two groups, with the exception of the incidence of implant tube exposure, which was four times greater in the group submitted to partial Tenon\'s capsule resection. In conclusion, after a mean follow-up period of 23.42 months, the measures of surgical success were comparable between the two groups. There was significant reduction in visual acuity in both groups, more markedly in the group not submitted to resection. The implant drainage tube became exposed four times more frequently in the group submitted to partial Tenon\'s capsule resection
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Reprodutibilidade do teste de sobrecarga hidrica realizado em diferentes horarios do dia / Reproductility of the water drinking test performde at different times of the day

Medina, Flavio Mac Cord, 1978- 01 December 2009 (has links)
Orientadores: Jose Paulo Cabral de Vasconcellos, Vital Paulino Costa / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciencias Medicas / Made available in DSpace on 2018-08-12T19:09:11Z (GMT). No. of bitstreams: 1 Medina_FlavioMacCord_M.pdf: 2280525 bytes, checksum: d64f96bf19c317e1e22a704a8562d282 (MD5) Previous issue date: 2009 / Resumo: Objetivo: Avaliar a reprodutibilidade do teste de sobrecarga hídrica (TSH) em diferentes horários em que é realizado, em pacientes com glaucoma primário de ângulo aberto (GPAA) e em indivíduos normais. Métodos: Quinze pacientes com GPAA e 30 indivíduos normais foram submetidos a três TSHs, realizados em diferentes horários do dia (às 7:00, 12:00 e 17:00), em três dias diferentes. Foram comparados os resultados dos testes em pacientes com GPAA e indivíduos normais. Foram analisadas a concordância e a correlação entre os valores de medida basal, pico e variação de pressão intra-ocular (PIO) (pico de PIO - PIO basal) nos testes realizados nos diferentes horários. Apenas as medidas do olho direito foram analisadas. Resultados: Os valores médios de medida basal, pico e variação de PIO foram significativamente maiores nos pacientes glaucomatosos que nos indivíduos normais, em todos os horários (p<0,05). A análise de Bland-Altman apresentou limites de concordância de pico e variação de PIO maiores do que o clinicamente aceitável (> 3 mmHg), apesar de o teste de Pearson demonstrar boa correlação entre os resultados. Conclusões: O TSH apresenta valores de pico e variação de Pio significativamente maiores em pacientes glaucomatosos que em indivíduos normais. Os baixos níveis de concordância entre os TSHs realizados em diferentes horários do dia sugerem uma baixa reprodutibilidade do TSH, que pode limitar sua aplicabilidade para diagnóstico e acompanhamento do glaucoma / Abstract: Purpose: To evaluate the reproducibility of the water drinking test (WDT) performed at different times of the day, in primary open angle glaucoma (POAG) patients and normal individuals. Methods: Fifteen patients with POAG and 30 normal individuals underwent three WDTs at different times of the day (7 AM, 12 PM, and 5 PM) on 3 different days. Test results in POAG patients and normal individuals were compared. Agreement and correlation of intraocular pressure (IOP) baseline levels, peak levels, and IOP change (peak IOP - baseline IOP) on tests performed at different times were evaluated. Only right eye measurements were analyzed. Results: Mean baseline IOP, peak IOP and IOP change were significantly higher in POAG patients than in normal individuals, at all time intervals (p<0.05). The Bland-Altman analysis demonstrated limits of agreement for IOP peak levels and IOP changes larger than the clinically acceptable (> 3 mmHg), even though Pearson's test revealed good correlation among the results. Conclusions: The mean IOP peak and mean IOP change observed during the WDT are significantly higher in POAG patients than in control individuals. Low levels of agreement among WDTs performed at different times of the day suggest a poor reproducibility of WDT, which may limit its applicability for the diagnosis and follow-up of glaucoma / Mestrado / Oftalmologia / Mestre em Ciências Médicas

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