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A thorough understanding of intraocular pressure homeostasis is the biological foundation for the development of new strategies to treat patients with elevated intraocular pressure or glaucoma. However, investigations on the physiology of intraocular pressure homeostasis are also important to gain more comprehensive insights into the pathogenesis of glaucoma and other diseases with associated alterations of intraocular pressure. The present review intends to give alternative insights into the biological and physical aspects of intraocular pressure regulation. The pressure-volume as well as the hydraulic model of intraocular pressure and also the relationship between ciliary blood flow and aqueous humor production, which has moved into the centre of interest because of its possible clinical relevance for glaucoma patients, will be explained. The authors Have attempted to interrelate the different aspects of intraocular pressure genesis and regulation in a comprehensive but understandable way., (© Georg Thieme Verlag KG Stuttgart · New York.)

Background: The aim of this study was to compare central corneal thickness (CCT) and intraocular pressure in patients participating in a glaucoma screening programme and patients who were examined in the glaucoma unit., Materials and Methods: 406 patients of a glaucoma screening programme (Salzburg-Moorfields collaborative glaucoma study) were included in this study. In addition a group of 406 patients who were admitted to the glaucoma clinic for a detailed glaucoma examination was included (outpatient clinic group). In all participants central corneal thickness (CCT) was measured and possible relations of CCT within the study groups were statistically analysed., Results: In the population screening group the mean central corneal thickness in normal subjects was 536+/-4.3 microm, in patients with ocular hypertension (OHT) 552+/-5.7 microm, patients suffering from a normal tension glaucoma (NTG) showed a mean CCT of 534+/-14.2 microm and those with primary open angle glaucoma (POAG) had a value of 521+/-17.9 microm. In the 'outpatient clinic group' the OHT subgroup had a mean CCT of 553+/-6.8 microm, the NTG subgroup of 529+/-26.5 microm and the one with POAG had a mean of 527+/-19.8 microm. In addition, CCT was measured in all glaucoma patients whose "partner" eye was healthy (544+/-5 microm) and included in this study as part of the normal subgroup. In both groups (screening group and outpatient group), CCT was significantly higher in OHT patients than in normals. In contrast, no statistically significant difference between normals and NTG or POAG patients was detected. Intraocular pressure was significantly lower in the screening groups than in the other ones., Conclusions: Our data confirm the previously published results concerning OHT and healthy subjects. In this study no significant difference between NTG or POAG subjects and normal eyes was detected. The lower IOP in the screening population can be explained by the fact that patients contacting the screening program are self selected whereas patients of the glaucoma unit are admitted by practising ophthalmologists and are, therefore, rather advanced cases or carrying special risk factors.

Purpose: One of the major shortcomings of longitudinal studies is the fact that instruments and technologies which were used at the beginning of the sampling might be replaced by others during the course of the study. The aim of the present work is to evaluate the relationship of optic disk parameters assessed with different methods and to test statistical possibilities of transforming these parameters into each other., Patients and Methods: The 'cup-to-disc ratio', the 'total disc area' and the 'neuroretinal rim area' of the human optic nerve of 131 eyes of 66 patients participating in the Salzburg-Moorfields Collaborative Glaucoma Study were assessed with two different laser scanning methods (TopSS and HRT II. The 'cup-to-disc ratio' was also determined subjectively by ophthalmologists of the glaucoma department. To compare the three data sets, the method of Bland-Altman, paired t-tests, as well as regression analyses were applied., Results: The 'cup-to-disc ratios' were: HRT II(R): 0.26 (95 % CI: 0.23 - 0.28), subjective assessment of 'cup-to-disc ratio': 0.33 (0.30 - 0.36) and TopSS: 0.43 (0.40 - 0.46). All three results are statistically significantly different (pairwise comparisons, p < 0.00001 each). Bland-Altman analysis shows that the differences of both objective methods exceed a magnitude that can be accepted for clinical purposes. The regression analyses reveal that the slope parameters are significantly different from 1.0. No regression models could be found with sufficiently small differences., Discussion: There are significant differences in the 'cup-to-disc Ratios' observed between the three methods. Therefore the application of a 'correction factor' cannot be advocated. Although such factors allow the means of the samples to agree, the differences of individual measurements still remain too large, to be useful for practical purposes.

Background: It is the aim of this study to describe both the relationship between age and prevalence as well as age and 5-year incidence of primary open angle glaucoma (POAG) for a homogeneous population cohort. The result of the regression model for the prevalence are compared with the models of Tuck-Crick and Quigley-Vitale. In addition, estimations for the number of 5-year incidence cases of POAG are provided for individuals at the age of 40-80 years in Austria for the years in 2001-2006, 2010-2015, 2020-2025 and 2030-2035., Patients and Methods: The "Salzburg Moorfields Collaborative Glaucoma Study" (SMCGS) is embedded in a government-supported glaucoma blindness prevention programme in Salzburg county, Austria, which is designed for a screening and follow-up period of at least 10 years. Each subject receives a complete ophthalmological examination. In total, the findings of 853 subjects are analysed and evaluated applying the guidelines of the European glaucoma society., Results: The results of the regression analysis for the prevalences are in good agreement with the models of Tuck-Crick and Quigley-Vitale. The best correlation was found for individuals between 40 and 80 years of age. The 5-year incidences increase is statistically significant (p < 0.001) with increasing age: the 5-year incidences of individuals at the age of 40, 50, 60, 70 and 80 years are 0.07 % (95 % confidence interval: 0.005 - 0.9 %), 0.2 % (0.04 - 1.2 %), 0.7 % (0.3 - 1.9 %), 2.3 % (1 - 5.2 %) and 6.9 % (1.7 - 24.0 %), respectively., Conclusion: The age-dependent prevalences in this glaucoma screening program are in good agreement with the regression models of Tuck-Crick and Quigley-Vitale, especially in the age range of 40 - 80 years. The model for the 5-year incidences describes the tight relationship between age and 5-year risk for POAG. We estimate the number of new POAG cases in Austria in 2001-2006, 2010-2015, 2020-2025 and 2030-2035 at the age between 40 and 80 years to reach 49 100, 52 100, 62 000 and 69 600 patients, respectively.

Background: This prospective, population-based longitudinal study describes prevalences and 5-year incidences of individuals with normal findings, ocular hypertension (OHT) and primary open-angle glaucoma (POAG) admitted to the Salzburg-Moorfields Collaborative Glaucoma Study (SMCGS)., Patients and Methods: The SMCGS is embedded in a government-supported glaucoma blindness prevention programme in Salzburg (Austria) which is designed for a minimum of 10-years follow-up. Each subject receives a complete ophthalmological examination. In total, the findings of 853 subjects with complete data sets were analysed and evaluated., Results: The prevalence of participants with normal findings was 75 % (95 % CI: 72 - 78 %) at the initial examination, decreasing to 64 % (95 % CI: 60 - 67 %) at the 5-year follow-up. The prevalence of OHT at the initial exam of 2.3 % (95 % CI: 1.4 - 3.6 %) increased to 3.5 % (95 % CI: 2.4 - 5.0 %) at the 5-year follow-up exam with an incidence of 1.2 % (95 % CI: 0.6 - 2.2 %). Finally, the prevalence of POAG of 0.6 % (95 % CI: 0.2 - 1.4 %) increased to 1.6 % (0.9 - 2.7 %) at the 5-year exam which corresponds to a 5-year incidence of POAG of 1.0 % (0.5 - 2.0 %)., Conclusion: The prevalence of POAG increases statistically significantly when compared at the initial and 5-year follow up exam (p = 0,002). Our results confirm the positive relation between age and the prevalence of POAG (odds ratio = 0.89, 95 % CI: 0.81 - 0.98). The prevalence and 5-year incidence rates in this glaucoma prevention study are similar to those of other population-based studies.