Eye-tracking-based visual field analysis (EFA): a reliable and precise perimetric methodology for the assessment of visual field defects.

OBJECTIVE: Several studies report evidence for training-related neuroplasticity in the visual cortex, while other studies suggest that improvements simply reflect inadequate eye fixation control during perimetric prediagnostics and postdiagnostics. METHODS AND ANALYSIS: To improve diagnostics, a new eye-tracking-based methodology for visual field analysis (eye-tracking-based visual field analysis (EFA)) was developed. The EFA is based on static automated perimetry and additionally takes individual eye movements in real time into account and compensates for them. In the present study, an evaluation of the EFA with the help of blind spots of 58 healthy participants and the individual visual field defects of 23 clinical patients is provided. With the help of the EFA, optical coherence tomography, Goldmann perimetry and a Humphrey field analyser, these natural and acquired scotomas were diagnosed and the results were compared accordingly. RESULTS: The EFA provides a SE of measurement of 0.38° for the right eye (OD) and 0.50° for the left eye (OS), leading to 0.44° of visual angle for both eyes (OU). Based on participants' individual results, the EFA provides disattenuated correlation (validity) of 1.00 for both OD and OS. Results from patients suffering from cortical lesions and glaucoma further indicate that the EFA is capable of diagnosing acquired scotoma validly and is applicable for clinical use. CONCLUSION: Outcomes indicate that the EFA is highly reliable and precise in diagnosing individual shape and location of scotoma and capable of recording changes of visual field defects (after intervention) with unprecedented precision. Test duration is comparable to established instruments and due to the high customisability of the EFA, assessment duration can be shortened by adapting the diagnostic procedure to the patients' individual visual field characteristics. Therefore, the saccade-compensating methodology enables researchers and healthcare professionals to rule out eye movements as a source of inaccuracies in pre-, post-, and follow-up assessments.

Lymphatic markers in the human optic nerve.

Tissues of the central nervous system (CNS), including the optic nerve (ON), are considered a-lymphatic. However, lymphatic structures have been described in the dura mater of human ON sheaths. Since it is known that lymphatic markers are also expressed by single non-lymphatic cells, these results need confirmation according to the consensus statement for the use of lymphatic markers in ophthalmologic research. The aim of this study was to screen for the presence of lymphatic structures in the adult human ON using a combination of four lymphatic markers. Cross and longitudinal cryo-sections of human optic nerve tissue (n = 12, male and female, postmortem time = 15.8 ± 5.5 h, age = 66.5 ± 13.8 years), were obtained from cornea donors of the Salzburg eye bank, and analyzed using immunofluorescence with the following markers: FOXC2, CCL21, LYVE-1 and podoplanin (PDPN; lymphatic markers), Iba1 (microglia), CD68 (macrophages), CD31 (endothelial cell, EC), NF200 (neurofilament), as well as GFAP (astrocytes). Human skin sections served as positive controls and confocal microscopy in single optical section mode was used for documentation. In human skin, lymphatic structures were detected, showing a co-localization of LYVE-1/PDPN/FOXC2 and CCL21/LYVE-1. In the human ON however, single LYVE-1+ cells were detected, but were not co-localized with any other lymphatic marker tested. Instead, LYVE-1+ cells displayed immunopositivity for Iba1 and CD68, being more pronounced in the periphery of the ON than in the central region. However, Iba1+/LYVE-1- cells outnumbered Iba1+/LYVE-1+ cells. PDPN, revealed faint labeling in human ON tissue despite strong immunoreactivity in rat ON controls, showing co-localization with GFAP in the periphery. In addition, pronounced autofluorescent dots were detected in the ON, showing inter-individual differences in numbers. In the adult human ON no lymphatic structures were detected, although distinct lymphatic structures were identified in human skin tissue by co-localization of four lymphatic markers. However, single LYVE-1+ cells, also positive for Iba1 and CD68 were present, indicating LYVE-1+ macrophages. Inter-individual differences in the number of LYVE-1+ as well as Iba1+ cells were obvious within the ONs, most likely resulting from diverse medical histories of the donors.

[Subconjunctival minimally invasive glaucoma surgery : Methods and clinical results]. / Subkonjunktivale minimalinvasive Glaukomchirurgie : Verfahren und klinische Ergebnisse.

Minimally invasive glaucoma surgery (MIGS) has been developed for all drainage pathways in glaucoma treatment. Besides implants overriding the resistance in the trabecular meshwork (iStent®, iStent Inject® [both Glaukos Germany GmbH, Wiesbaden, Germany], Hydrus Microstent® [Ivantis, Irvine, CA, USA]) and draining to the suprachoroidal space (Cypass Micro Stent® [Alcon Laboratories, Inc., Fort Worth, TX, USA], iStent Supra® [Glaukos Germany GmbH]), surgeons can further drain aqueous humor into the subconjunctival space with a transscleral MIGS implant (XEN45® [Allergan Plc., Dublin, Irland]). The XEN45® is a gelatine tube 6 mm in length, which is implanted ab interno via a small corneal incision through the sclera. Additional aqueous humor is drained from the anterior chamber via the tube and filtered in a filter cushion in order to sink the total drainage resistance. The internal diameter of the lumen of the implant is 45 µm, therefore a passive resistance is present for prevention of postoperative hypotension. The by-passed aqueous humor forms a conjunctival bleb. Although the first study results are promising in terms of efficacy and safety, further studies are necessary before a clear picture of the effectiveness, safety, advantages and disadvantages of the gelatine tube can be drawn.

Lymphatic and vascular markers in an optic nerve crush model in rat.

Only few tissues lack lymphatic supply, such as the CNS or the inner eye. However, if the scleral border is compromised due to trauma or tumor, lymphatics are detected in the eye. Since the situation in the optic nerve (ON), part of the CNS, is not clear, the aim of this study is to screen for the presence of lymphatic markers in the healthy and lesioned ON. Brown Norway rats received an unilateral optic nerve crush (ONC) with defined force, leaving the dura intact. Lesioned ONs and unlesioned contralateral controls were analyzed 7 days (n = 5) and 14 days (n = 5) after ONC, with the following markers: PDGFRb (pericyte), Iba1 (microglia), CD68 (macrophages), RECA (endothelial cell), GFAP (astrocyte) as well as LYVE-1 and podoplanin (PDPN; lymphatic markers). Rat skin sections served as positive controls and confocal microscopy in single optical section mode was used for documentation. In healthy ONs, PDGFRb is detected in vessel-like structures, which are associated to RECA positive structures. Some of these PDGFRb+/RECA+ structures are closely associated with LYVE-1+ cells. Homogenous PDPN-immunoreactivity (IR) was detected in healthy ON without vascular appearance, showing no co-localization with LYVE-1 or PDGFRb but co-localization with GFAP. However, in rat skin controls PDPN-IR was co-localized with LYVE-1 and further with RECA in vessel-like structures. In lesioned ONs, numerous PDGFRb+ cells were detected with network-like appearance in the lesion core. The majority of these PDGFRb+ cells were not associated with RECA-IR, but were immunopositive for Iba1 and CD68. Further, single LYVE-1+ cells were detected here. These LYVE-1+ cells were Iba1-positive but PDPN-negative. PDPN-IR was also clearly absent within the lesion site, while LYVE-1+ and PDPN+ structures were both unaltered outside the lesion. In the lesioned area, PDGFRb+/Iba1+/CD68+ network-like cells without vascular association might represent a subtype of microglia/macrophages, potentially involved in repair and phagocytosis. PDPN was detected in non-lymphatic structures in the healthy ON, co-localizing with GFAP but lacking LYVE-1, therefore most likely representing astrocytes. Both, PDPN and GFAP positive structures are absent in the lesion core. At both time points investigated, no lymphatic structures can be identified in the lesioned ON. However, single markers used to identify lymphatics, detected non-lymphatic structures, highlighting the importance of using a panel of markers to properly identify lymphatic structures.

Time-dependent retinal ganglion cell loss, microglial activation and blood-retina-barrier tightness in an acute model of ocular hypertension.

Glaucoma is a group of neurodegenerative diseases characterized by the progressive loss of retinal ganglion cells (RGCs) and their axons, and is the second leading cause of blindness worldwide. Elevated intraocular pressure is a well known risk factor for the development of glaucomatous optic neuropathy and pharmacological or surgical lowering of intraocular pressure represents a standard procedure in glaucoma treatment. However, the treatment options are limited and although lowering of intraocular pressure impedes disease progression, glaucoma cannot be cured by the currently available therapy concepts. In an acute short-term ocular hypertension model in rat, we characterize RGC loss, but also microglial cell activation and vascular alterations of the retina at certain time points. The combination of these three parameters might facilitate a better evaluation of the disease progression, and could further serve as a new model to test novel treatment strategies at certain time points. Acute ocular hypertension (OHT) was induced by the injection of magnetic microbeads into the rat anterior chamber angle (n = 22) with magnetic position control, leading to constant elevation of IOP. At certain time points post injection (4d, 7d, 10d, 14d and 21d), RGC loss, microglial activation, and microvascular pericyte (PC) coverage was analyzed using immunohistochemistry with corresponding specific markers (Brn3a, Iba1, NG2). Additionally, the tightness of the retinal vasculature was determined via injections of Texas Red labeled dextran (10 kDa) and subsequently analyzed for vascular leakage. For documentation, confocal laser-scanning microscopy was used, followed by cell counts, capillary length measurements and morphological and statistical analysis. The injection of magnetic microbeads led to a progressive loss of RGCs at the five time points investigated (20.07%, 29.52%, 41.80%, 61.40% and 76.57%). Microglial cells increased in number and displayed an activated morphology, as revealed by Iba1-positive cell number (150.23%, 175%, 429.25%,486.72% and 544.78%) and particle size analysis (205.49%, 203.37%, 412.84%, 333.37% and 299.77%) compared to contralateral control eyes. Pericyte coverage (NG2-positive PC/mm) displayed a significant reduction after 7d of OHT in central, and after 7d and 10d in peripheral retina. Despite these alterations, the tightness of the retinal vasculature remained unaltered at 14 and 21 days after OHT induction. While vascular tightness was unchanged in the course of OHT, a progressive loss of RGCs and activation of microglial cells was detected. Since a significant loss in RGCs was observed already at day 4 of experimental glaucoma, and since activated microglia peaked at day 10, we determined a time frame of 7-14 days after MB injection as potential optimum to study glaucoma mechanisms in this model.

Characterization of dsRed2-positive cells in the doublecortin-dsRed2 transgenic adult rat retina.

Doublecortin (DCX) is predominantly expressed in neuronal precursor cells and young immature neurons of the developing and adult brain, where it is involved in neuronal differentiation, migration and plasticity. Moreover, its expression pattern reflects neurogenesis, and transgenic DCX promoter-driven reporter models have been previously used to investigate adult neurogenesis. In this study, we characterize dsRed2 reporter protein-expressing cells in the adult retina of the transgenic DCX promoter-dsRed2 rat model, with the aim to identify cells with putative neurogenic activity. Additionally, we confirmed the expression of the dsRed2 protein in DCX-expressing cells in the adult hippocampal dentate gyrus. Adult DCX-dsRed2 rat retinas were analyzed by immunohistochemistry for expression of DCX, NF200, Brn3a, Sox2, NeuN, calbindin, calretinin, PKC-a, Otx2, ChAT, PSA-NCAM and the glial markers GFAP and CRALBP, followed by confocal laser-scanning microscopy. In addition, brain sections of transgenic rats were analyzed for dsRed2 expression and co-localization with DCX, NeuN, GFAP and Sox2 in the cortex and dentate gyrus. Endogenous DCX expression in the adult retina was confined to horizontal cells, and these cells co-expressed the DCX promoter-driven dsRed2 reporter protein. In addition, we encountered dsRed2 expression in various other cell types in the retina: retinal ganglion cells (RGCs), a subpopulation of amacrine cells, a minority of bipolar cells and in perivascular cells. Since also RGCs expressed dsRed2, the DCX-dsRed2 rat model might offer a useful tool to study RGCs in vivo under various conditions. Müller glial cells, which have previously been identified as cells with stem cell features and with neurogenic potential, did express neither endogenous DCX nor the dsRed2 reporter. However, and surprisingly, we identified a perivascular glial cell type expressing the dsRed2 reporter, enmeshed with the glia/stem cell marker GFAP and colocalizing with the neural stem cell marker Sox2. These findings suggest the so far undiscovered existence of perivascular associated cell with neural stem cell-like properties in the adult retina.

A novel, microscope based, non-invasive laser Doppler flowmeter for choroidal blood flow assessment.

Impaired ocular blood flow is involved in the pathogenesis of numerous ocular diseases like glaucoma or AMD. The purpose of the present study was to introduce and validate a novel, microscope based, non-invasive Laser Doppler Flowmeter (NI-LDF) for measurement of blood flow in the choroid. The custom made NI-LDF was compared with a commercial fiber optic based laser Doppler flowmeter (Perimed PF4000). Linearity and stability of the NI-LDF were assessed in a silastic tubing model (i.d. 0.3 mm) at different flow rates (range 0.4-3 ml/h). In a rabbit model continuous choroidal blood flow measurements were performed with both instruments simultaneously. During blood flow measurements ocular perfusion pressure was changed by manipulations of intraocular pressure via intravitreal saline infusions. The NI-LDF measurement correlated linearly to intraluminal flow rates in the perfused tubing model (r = 0.99, p < 0.05) and remained stable during a 1 h measurement at a constant flow rate. Rabbit choroidal blood flow measured by the PF4000 and the NI-LDF linearly correlated with each other over the entire measurement range (r = 0.99, y = x∗1.01-12.35 P.U., p < 0.001). In conclusion, the NI-LDF provides valid, semi quantitative measurements of capillary blood flow in comparison to an established LDF instrument and is suitable for measurements at the posterior pole of the eye.

[Biological and physical aspects of intraocular pressure]. / Biologische und physikalische Aspekte des Augendrucks.

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.

Ciliary blood flow and aqueous humor production.

Aqueous humor production is a metabolically active process sustained by the delivery of oxygen and nutrients and removal of metabolic waste by the ciliary circulation. This article describes our investigations into the relationship between ciliary blood flow and aqueous humor production. The results presented indicate that there is a dynamic relationship between ciliary blood flow and aqueous humor production, with production being blood flow independent above a critical level of perfusion, and blood flow dependent below it. The results also show that the plateau portion of the relationship shifts up or down depending on the level of secretory stimulation or inhibition, and that oxygen is one critical factor provided by ciliary blood flow. Also presented is a theoretical model of ocular hydrodynamics incorporating these new findings.

Aberrant heterodimerization of keratin 16 with keratin 6A in HaCaT keratinocytes results in diminished cellular migration.

Keratin filaments form obligatory heterodimers consisting of one type I and one type II keratin that build the intermediate filaments. In keratinocytes, type II keratin 6 (K6) interacts with type I keratin 16 (K16). We previously showed that the intermediate filament protein K16 is up-regulated in aged human skin. Here, we report that there is an obvious imbalance of K16 to K6 mRNA in in vivo and in vitro aging, which possibly leads to cellular effects. To unveil a possible biological function of K16 overexpression we investigated the migration potential of keratinocytes having up-regulated K16 expression in vitro. Two cell lines were established by transfection of human keratinocytes (HaCaT cells) with K16 or control vectors and subsequent fluorescence-activated cell sorting. By performing migration assays we were able to show a 90% reduction in the migration ability of the K16-overexpressing keratinocytes. In addition, a delay in wound closure associated with K16-overexpressing cells was shown by scratch assays. Transient overexpression of K6A in K16-overexpressing keratinocytes partially corrected the cell-migration defect. By real-time PCR we excluded co-regulation of the annotated interaction partner, K6, in the K16 cell line. Finally, we observed a decreased level of tyrosine phosphorylation in K16-overexpressing cells. Taken together, these data highlight the possibility of a physiological role for K6/K16 heterodimers in keratinocyte cell migration, in addition to the heterodimer's known functions in cell differentiation and mechanical resilience.

[Comparison of central corneal thickness in patients participating in a glaucoma screening programme and those who were examined in the glaucoma unit]. / Vergleich der mittleren zentralen Hornhautdicke bei Patienten eines Glaukomvorsorgeprogramms und ambulanten Glaukompatienten.

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.

[The 'cup-to-disc ratio': a comparison of TopSS, HRT II and subjective findings]. / Die 'Cup-to-Disk Ratio': Ein Vergleich von TopSS, HRT II und subjektiver Befundung.

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.

[On the relationship between age and prevalence and/or incidence of primary open-angle glaucoma in the "Salzburg-Moorfields Collaborative Glaucoma Study"]. / Uber den Zusammenhang zwischen Lebensalter und Prävalenz sowie Inzidenz des primären Offenwinkelglaukoms in der "Salzburg-Moorfields-Collaborative-Glaucoma"-Studie.

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.

The projected increase in glaucoma due to the aging population in Austria from 2001 to 2031: results based on data of the Salzburg-Moorfields Collaborative Glaucoma Study.

PURPOSE: The aim of this study is to present the projected increase in definite primary open angle glaucoma (POAG) and related diseases in Austria from 2001 to 2031. METHODS: The present work is based on two data sources: population projections in Austria and detection rates of the Salzburg-Moorfields Collaborative Glaucoma Study for Austrians in the age groups 40-54 years, 55-69 years, and 70 years and above. The estimates of this glaucoma screening program are based on a total of 3419 subjects. Sensitivity analyses were applied to test the effects of higher and lower sets of prevalence assumptions on the extent of the probable projections. RESULTS: The number of Austrians with definite POAG, early POAG, POAG suspects, and ocular hypertension (OHT) is expected to increase until 2031 by 0.5%, 43.1%, and 65.6% in the three age groups specified above, respectively. The overall number of Austrians with POAG at the age of 40 or older is estimated to increase from 67,600 in 2001 to 96,400 in 2031. This corresponds to an increase of 42% from 2001 to 2031 (lower scenario: 37%, upper scenario: 47%). Similar increases are expected for individuals with early POAG, POAG suspects, and OHT. CONCLUSIONS: These projections provide an objective basis to estimate the resources that may be needed by health authorities and care providers such as ophthalmologists in the future and should help to design glaucoma blindness prevention programs or screening studies in Austria. The predicted continuous increase of Europe's older population will prove to become a challenge for public health professionals not only for diagnosis and monitoring, but also for the treatment of glaucoma.

Resource use and costs for a glaucoma screening program in Austria: an 8-year review: a cost-consequence analysis based on the Salzburg-Moorfields Collaborative Glaucoma Study.

PURPOSE: The aim of this study is to report costs, detection rates, and resources needed for detection of primary open angle glaucoma and related diseases in a glaucoma screening program in Salzburg, Austria, over a period of 8 years. METHODS: The Salzburg-Moorfields Collaborative Glaucoma Study performed a complete ophthalmologic examination on a total of 4864 subjects within a study period of approximately 8 years (98 months). The total numbers reported are total number of subjects screened at the initial examination and follow-up examinations; total working hours and estimated working hours per visit for one ophthalmologist and two medical assistants; direct costs per visit; detection rates for subjects; and corresponding costs per true positive case diagnosed with definite primary open angle glaucoma (POAG), early POAG, POAG suspect, ocular hypertension (OHT), and glaucoma artefact. RESULTS: Within the screening period of 98 months, a total of 9427 examinations and second verification checks were performed: 5466 at the initial examination, 404 at the 1-year follow-up, 815 at the 2-year follow-up, 339 at the 3-year follow-up, 225 at the 4-year follow-up, 1059 at the 5-year follow-up, 996 at the 6-year follow-up, 118 at the 7-year follow-up, and 5 at the 8-year follow-up. The total amount of time spent for screening was 23,814 working hours. We estimate the costs per visit at EUR 123 for each initial examination, EUR 28 for each second confirmation check, and EUR 95 per follow-up examination. The following detection rates were observed: definite POAG: 1.7% (95% CI: 1.3-2.2%), early POAG: 2.9% (95% CI: 2.3-3.5%), POAG suspect: 8.5% (95% CI: 7.6-9.4%), OHT: 2.2% (95% CI: 1.7-2.7%), glaucoma artefact or other causes: 5.8% (95% CI: 5.1-6.6%), normal cases: 79% (95% CI: 78-80%). CONCLUSIONS: Direct costs per visit were considerably higher than those reported in the Netherlands or the United Kingdom. If a health care provider decides to perform a glaucoma screening within this setting, the costs for the detection of a new case are EUR 7250 for definite POAG, EUR 4250 for early POAG, EUR 1450 for POAG suspect, EUR 5600 for OHT, EUR 2100 for glaucoma artefact case, and EUR 156 for a normal case.

Effects of a topical alpha2 adrenergic agonist on ciliary blood flow and aqueous production in rabbits.

The relationship between ciliary perfusion and aqueous production is poorly understood. It was recently reported that aqueous production decreases when ciliary blood flow is reduced by lowering the ocular perfusion pressure, and hypothesized that drug-induced reduction of ciliary blood flow would also decrease aqueous production. In the present study, we test this hypothesis with an alpha2 adrenergic agonist (brimonidine) formulated for topical application. When used acutely, brimonidine decreases intraocular pressure (IOP) by suppressing aqueous production, although its mechanism of action is unclear. The experiments were performed in four groups of anesthetized rabbits (n=33) in which the following variables were measured: ocular mean arterial pressure (OMAP), IOP, orbital venous pressure (OVP), aqueous flow, ciliary blood flow, ciliary oxygen tension (PO2), episcleral venous pressure (EVP), carotid blood flow and heart rate. The measurements were made before and after brimonidine (0.15%, 40 microl) was applied to the cornea. Brimonidine decreased IOP (-33%, p<0.01), aqueous flow (-39%, p<0.01), ciliary blood flow (-37%, p<0.01), EVP (-42%, p<0.01) and ciliary PO2 (-32%, p<0.05). We conclude that topical brimonidine is a ciliary vasoconstrictor, and that alpha2 adrenergic agonist-induced decreases in ciliary blood flow decrease aqueous production.

[The Salzburg-Moorfields Collaborative Glaucoma Study: first results of the prevalence and 5-year incidences in this prospective, population-based longitudinal study]. / Die Salzburg-Moorfields-Collaborative-Glaucoma Study: Erste Ergebnisse der Prävalenzen und 5-Jahres-Inzidenzen in dieser prospektiven, bevölkerungsbasierten Longitudinalstudie.

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.

Alpha-fodrin is cleaved by caspase-3 in a chronic ocular hypertensive (COH) rat model of glaucoma.

PURPOSE: alpha-Fodrin is a neuronal cytoskeletal protein and a known caspase-3 target. We sought to determine whether caspase-3 cleaves alpha-fodrin in COH rat retinas and whether this process is reduced by adeno-associated virus (AAV)-induced retinal ganglion cell expression of baculovirus inhibitory repeat-containing 4 (BIRC4), a potent caspase-3 inhibitor. METHODS: Ocular hypertension was induced unilaterally in five rat eyes by limbal injection of hypertonic saline. In a similar experiment, ocular hypertension was induced in four eyes pre-treated with an intravitreal injection of AAV-BIRC4 to assess alpha-fodrin cleavage. Western immunoblotting was performed on all retinas. RESULTS: Caspase-3 cleavage of alpha-fodrin yields a specific 120kDa protein fragment. COH retina immunoblots indicated significantly more caspase-3 cleavage of alpha-fodrin than controls (P < 0.01, paired t-test). Inhibition of retinal caspase-3 activity with BIRC4 reduced caspase-3-mediated alpha-fodrin cleavage compared to controls. CONCLUSIONS: This confirms our previous finding of caspase-3 cleavage of alpha-fodrin in COH retinas and parallels pathology seen in Alzheimer's disease, in which neurons undergo chronic caspase activation, slow build-up of cleavage products, and delayed apoptosis. If caspase activation in glaucoma leads to protracted rather than rapid retinal ganglion cell apoptosis, a much longer therapeutic window exists for apoptosis inhibition with caspase inhibitors such as BIRC4.

Effects of nitric oxide synthase inhibition on ciliary blood flow, aqueous production and intraocular pressure.

A prior study found that inhibition of nitric oxide synthase with L-NAME causes a large, rapid decrease in IOP in anesthetized rabbits. In this follow-up study we sought to determine if this hypotensive effect was due to decreased aqueous production, possibly caused by ciliary vasoconstriction. Two protocols were performed in anesthetized rabbits. In the first protocol, mean arterial pressure (MAP) and IOP were measured by direct cannulation, and aqueous flow was measured by fluorophotometry, before and after L-NAME (5 mg kg(-1), i.v., n = 7). In the second protocol, ciliary blood flow was measured transclerally by laser Doppler flowmetry while MAP was varied mechanically over a wide range before and after L-NAME (5 mg kg(-1), i.v., n = 8). L-NAME caused a significant increase in MAP and decreases in IOP, ciliary blood flow and aqueous flow. L-NAME also caused a significant downward shift in the ciliary pressure-flow relation over the entire pressure range examined. The results indicate that L-NAME causes ciliary vasoconstriction and decreases aqueous production, suggesting that the L-NAME ocular hypotensive effect may be due in part to a blood flow-dependent decrease in aqueous production. However, assuming no uveoscleral outflow and constant episcleral venous pressure and outflow facility, the decrease in aqueous flow accounts for 66% of the drop in IOP, suggesting an additional effect of L-NAME on aqueous outflow.