The rising tide of rhegmatogenous retinal detachment in Germany: a nationwide analysis of the incidence, from 2005 to 2021.

PURPOSE: This nationwide study aims to delineate the incidence and trends of rhegmatogenous retinal detachment (rRD) in Germany across 17 years (2005-2021). METHODS: We conducted a retrospective cohort study using data from the German Federal Statistics Office and the Institute for the Hospital Remuneration System (InEK). The dataset includes approximately 19 million annual inpatient admissions annually. Retinal detachment was identified through ICD-10 code H33.0. Adjusted incidence rates were estimated after excluding reoperation cases. We used R Statistical Software to calculate estimates to 2021, and Tableau for visualisation. RESULTS: From 2005 to 2021, Germany reported 332,650 rRD cases, with males consistently more affected. Adjusted incidence rose from 15.6 per 100,000 in 2005 to 24.8 in 2021. Variable annual percentage changes in incidence were noted, averaging 4.0% for males and 2.6% for females. The annual mean age of affected individuals ranged from 60.2 to 62 years, with a median age between 62 and 63, suggesting increasing diagnoses at younger ages. Hospital stays declined from 6 to 3.3 days, and higher management rates were observed in Saarland and Rhineland-Palatine. CONCLUSION: The study confirms an increasing incidence of rRD in Germany from 2005 to 2021, particularly among males. These findings call for further research to investigate the underlying causes. Collaboration among healthcare professionals, researchers, and policymakers is essential for effective management and improved visual outcomes.

LASER FLARE PHOTOMETRY IN PRIMARY RHEGMATOGENOUS RETINAL DETACHMENT: An Evaluation of 2,487 Cases.

PURPOSE: Exploratory analysis associated with the prospective, multicenter, randomized PRIVENT trial. To characterize the associations between laser flare photometry and anatomical and epidemiological features of rhegmatogenous retinal detachment (RRD). METHODS: The authors measured laser flare values of all 3,048 prescreened patients excluding those with comorbidities. A mixed regression analysis evaluated the strength of the influencing factors like age, sex, lens status, and presence and extent of RRD on laser flare. RESULTS: Rhegmatogenous retinal detachment was more frequent in men (65.8%) than in women (34.2%, P < 0.001) and in right (52%) than in left eyes (48%, P = 0.045). Phakic RRD affected less quadrants and was less likely to be associated with macula-off status than pseudophakic RRD (48.4% vs. 58.0% macula off, 23% vs. 31% ≥3 quadrants, P < 0.001). Laser flare of affected eyes was significantly higher compared with fellow eyes (12.6 ± 15.2 vs. 8.3 ± 7.4 pc/ms, P < 0.001). The factors age, sex, lens status, presence of RRD, and the number of quadrants affected were independent influencing factors on laser flare. R 2 was 0.145 for phakic and 0.094 for pseudophakic eyes. CONCLUSION: The results indicate that there may be more factors affecting laser flare than previously assumed. This might limit flare as predictive value for PVR and retinal redetachment.

How to improve IARC's RF-EMF cancer hazard communication.

A crucial aspect of IARC's evaluation of the relative carcinogenicity of agents is the communication of its conclusions. The present paper addressed the experimental risk perception literature pertaining to IARC's radiofrequency electromagnetic field evaluation communication, and derived specific recommendations for improving it.

Intravitreal 5-Fluorouracil and Heparin to Prevent Proliferative Vitreoretinopathy: Results from a Randomized Clinical Trial.

PURPOSE: Proliferative vitreoretinopathy (PVR) is the major cause for surgical failure after primary rhegmatogenous retinal detachment (RRD). So far, no therapy has been proven to prevent PVR. Promising results for 5-fluorouracil (5-FU) and low-molecular weight heparin (LMWH) in high-risk eyes have been reported previously. The objective of this trial was to examine the effect of adjuvant intravitreal therapy with 5-FU and LMWH compared with placebo on incidence of PVR in high-risk patients with primary RRD. DESIGN: Randomized, double-blind, controlled, multicenter, interventional trial with 1 interim analysis. PARTICIPANTS: Patients with RRD who were considered to be at high risk for PVR were included. Risk of PVR was assessed by noninvasive aqueous flare measurement using laser flare photometry. METHODS: Patients were randomized 1:1 to verum (200 mg/ml 5-FU and 5 IU/ml dalteparin) and placebo (balanced salt solution) intravitreally applied during routine pars plana vitrectomy. MAIN OUTCOME MEASURES: Primary end point was the development of PVR grade CP (full-thickness retinal folds or subretinal strands in clock hours located posterior to equator) 1 or higher within 12 weeks after surgery. For grading, an end point committee assessed fundus photographs. Secondary end points included best-corrected visual acuity and redetachment rate. A group sequential design with 1 interim analysis was applied using the O'Brien and Fleming boundaries. Proliferative vitreoretinopathy grade CP incidence was compared using a Mantel-Haenszel test stratified by surgeon. RESULTS: A total of 325 patients in 13 German trial sites had been randomized (verum, n = 163; placebo, n = 162). In study eyes, mean laser flare was 31 ± 26 pc/ms. No significant difference was found in PVR rate. Primary analysis in the modified intention-to-treat population results were: verum 28% vs. placebo 23% (including not assessable cases as failures); odds ratio [OR], 1.25; 95% confidence interval [CI], 0.76-2.08; P = 0.77. Those in the per-protocol population were: 12% vs. 12%; OR, 1.05; 95% CI, 0.47-2.34; P = 0.47. None of the secondary end points showed any significant difference between treatment groups. During the study period, no relevant safety risks were identified. CONCLUSIONS: Rate of PVR did not differ between adjuvant therapy with 5-FU and LMWH and placebo treatment in eyes with RRD.

Age- and sex-related variations of individual retinal layer thickness in the foveal center of healthy eyes.

Alterations of the visual function during life are associated with changes in the morphological parameters of the outer retinal layers of the fovea. We evaluated age- and sex-related variations of the mean thicknesses of the different retinal layers at the central foveola which provides the maximal visual acuity. The vertical expansions of the following structures were measured on spectral-domain optical coherence tomographic images of 2944 healthy eyes of 1990 subjects with ages between 5 and 85 years: the total thickness of the retinal tissue, the thickness of the retinal pigment epithelium, the lengths of photoreceptors (receptor segments), photoreceptor outer segments (POS), and photoreceptor inner segments (PIS), and the thicknesses of the ellipsoid zone (EZ), myoid zone (MZ), external limiting membrane, outer nuclear layer, Henle fiber layer, and the horizontal layer of the Müller cell cone. We found diverse morphologies of the central photoreceptor layer with different thicknesses of the EZ and interdigitation zone lines. The mean total thickness of the retinal tissue at the central foveola showed three periods: it increased between 5 and about 41 years of age, displayed a plateau until about 52 years, and decreased continuously thereafter. Photoreceptors, POS, and PIS displayed their maximal mean lengths between 5 and about 36 years of age; the lengths decreased continuously between 36 and 85 years of age. Whereas the mean thickness of the EZ did not alter across the life span, the mean thickness of MZ displayed three periods: it increased between 5 and about 21 years of age, showed a plateau until about 36 years, and decreased considerably thereafter. Sex differences were observed for five parameters in eyes of subjects aging between 55 and 85 years. We suggest that the MZ thickness reflects the level of the metabolic activity of photoreceptors. The increase in the MZ thickness, likely reflecting increasing metabolic activity of photoreceptors, might contribute to the improvement of visual function in young subjects. The decrease of the MZ thickness in the fovea of elderly might reflect a decrease of the metabolic activity perhaps resulting from mitochondrial dysfunction which is known to occur in photoreceptors of aged eyes.

The epidemiology of uveal melanoma in Germany: a nationwide report of incidence and survival between 2009 and 2015.

PURPOSE: To calculate the overall incidence of uveal melanoma in Germany and to compare incidences in different German states. In addition, we computed the overall and cancer-specific survival rates nationwide. METHODS: Incidence data for the period between 2009 and 2015, covering the entire German population, was collected through the German Center for Cancer Registry. ICD-O-3 topography codes C69.3-C69.4 and histology codes for melanoma subtypes were used to collect the incidence data. Confidence Intervals with a level of 95% (95% CI) were calculated for rates. Survival was calculated using the Kaplan-Meier. The log-rank test was used for survival comparisons. RESULTS: This study comprised 3654 patients with uveal melanomas, including 467 (12.8%) with iridial and ciliary body tumors. The overall age-standardized incidence rate (ASIR) was 6.41 person per million. Generally, the ASIR was higher in males than females (6.67 (95% CI 6.37-6.98) vs. 6.16 (95% CI 5.88-6.45 per million). Higher crude incidence rates were noted in the northeastern states (12.5 per million (95% CI 10.5-14.7) in Mecklenburg-Vorpommern) compared with the southwestern states (2.1 per million (95% CI 1.7-2.6) in Hessen). The 5-year overall survival stood at 47%, while the cancer-specific survival stood at 84%. Multivariate analysis showed that women, younger patients, and patients living in Berlin achieved significantly higher overall survival. CONCLUSION: Overall ASIR of uveal melanoma in Germany indicates that the disease is more common in males and that it follows the same geographical distribution previously noted in central European countries, with the highest incidence in northern parts of Germany.

Effects of as-if risk framing of hazards on risk perception and its rebuttal.

BACKGROUND: The difference between hazard and risk is crucial in risk assessment but rather unknown by non-experts. Hyper-partisan activists could use this knowledge gap to amplify risk perception by framing hazards as as-if risks, i.e., describing hazards as if their exposure is critical. Thus, using this as-if risk framing can trigger impressions that a risk is present. Until now, this framing technique and its rebuttal was not empirically analyzed. METHOD: An experimental 2 × 2 factorial online study (N = 404) with repeated measures after intervention was conducted to investigate how framing (hazard vs. as-if risk) and stigmatization (stigmatized vs. non-stigmatized chemical agent) affects affective and cognitive risk perception using an example of exposure to drifting pesticides. RESULTS: As-if risk framing increased risk perception, effects of stigmatization were not observed. However, the a-priori risk perception influences the recorded risk perceptions after the experimental treatment. Rebuttal was successful, i.e., subjects with elevated risk perceptions due to as-if risk framing reduced their risk perception after receiving corrective information. CONCLUSIONS: As-if risk framing investigated here is not a sequestered case. Accordingly, the present study may offer general insights into correcting biased information that neglects the difference between hazard and risk. Risk communicators can benefit from these insights.

Hypoxic and osmotic expression of Kir2.1 potassium channels in retinal pigment epithelial cells: Contribution to vascular endothelial growth factor expression.

Retinal pigment epithelial (RPE) cells express different subtypes of inwardly rectifying potassium (Kir) channels. We investigated whether human and rat RPE cells express genes of strongly rectifying Kir2 channels. We also determined the hypoxic and hyperosmotic regulation of Kir2.1 gene expression in cultured human RPE cells and the effects of siRNA-mediated knockdown of Kir2.1 on VEGFA expression, VEGF secretion, proliferation, and viability of the cells. Extracellular hyperosmolarity was induced by addition of NaCl or sucrose. Hypoxia and chemical hypoxia were produced by cell culture in 0.25% O2 and addition of CoCl2, respectively. Gene expression levels were evaluated by real-time RT-PCR. Rat RPE cells contained Kir2.1, Kir2.2, Kir2.3, and Kir2.4 gene transcripts while human RPE cells contained Kir2.1, Kir2.2, and Kir2.4 transcripts. Immunocytochemical data may suggest that Kir2.1 protein in cultured human cells is expressed in both perinuclear and plasma membranes. Kir2.1 gene expression and Kir2.1 protein level in human cells increased under hypoxic and hyperosmotic conditions. The expression of the Kir2.1 gene was mediated in part by diverse intracellular signal transduction pathways and transcription factor activities under both conditions; the hyperosmotic, but not the CoCl2-induced Kir2.1 gene expression was dependent on intracellular calcium signaling. Autocrine/paracrine activation of purinergic receptors contributed to Kir2.1 gene expression under hyperosmotic (P2Y1, P2Y2, P2X7) and CoCl2-induced conditions (P2Y2, P2X7). Exogenous VEGF, TGF-ß1, and blood serum decreased Kir2.1 gene expression. Inhibition of VEGF receptor-2 increased the Kir2.1 gene expression under control conditions and in CoCl2-simulated hypoxia, and decreased it under high NaCl conditions. Knockdown of Kir2.1 by siRNA inhibited the CoCl2-induced and hyperosmotic transcription of the VEGFA gene and caused a delayed decrease of the constitutive VEGFA gene expression while VEGF protein secretion was not altered. Kir2.1 knockdown stimulated RPE cell proliferation under control and hyperosmotic conditions without affecting cell viability. The data indicate that Kir2.1 channel activity is required for the expression of the VEGFA gene and inhibits the proliferation of RPE cells. Under control and hypoxic conditions, the extracellular VEGF level may regulate the production of VEGF via its inhibitory effect on the Kir2.1 gene transcription; this feedback loop may prevent overproduction of VEGF.

Foveal configurations with disappearance of the foveal pit in eyes with macular pucker: Presumed role of Müller cells in the formation of foveal herniation.

Many eyes with macular pucker are characterized by a centripetal displacement of the inner foveal layers which may result in a disappearance of the foveal pit. In this retrospective case series of 90 eyes with macular pucker of 90 patients, we describe using spectral-domain optical coherence tomography different foveal configurations with ectopic inner foveal layers, document the relationship between posterior vitreous detachment (PVD) and idiopathic epiretinal membrane (ERM) formation and spontaneous and postoperative morphological alterations of the fovea, and propose an active role of Müller cells in the development of foveal herniation. We found that ERM were formed during or after partial perifoveal PVD, or after foveal deformations caused by tissue edema. The ERM-mediated centripetal displacement of the inner foveal layers and in various eyes anterior hyaloidal traction caused a disappearance of the foveal pit and an anterior stretching of the foveola with a thickening of the central outer nuclear layer (ONL). After the edges of the thickened inner layers of the foveal walls moved together, continuous centripetal displacement of the inner foveal layers generated a bulge of the fovea towards the vitreous (foveal herniation). Macular pseudoholes with a herniation of the inner foveal layers show that the outer layer of the protruding foveal walls is the outer plexiform layer (OPL). If the ERM covered the foveal walls and parafova, but not the foveola, the inner layers of the foveal walls were not fully centripetally displaced and the foveal pit was present. The visual acuity of eyes with ectopic inner foveal layers was inversely correlated with the thickness of the foveal center. Spontaneous morphological alterations after disappearance of the foveal pit may include the development of cystoid macular edema or additional thickening of the foveal tissue and foveal herniation. The foveal configuration with ectopic inner layers of the foveal walls and a thick central ONL persisted over longer postoperative time periods. The data show that the centripetal displacement of the inner foveal layers in eyes with macular pucker, which results in a disappearance of the foveal pit, may also generate foveal herniation which is suggested to be caused by contraction of Müller cell processes in the OPL. The centripetal displacement of the inner foveal layers and the formation of foveal herniation are suggested to reverse the foveal pit formation during development.

Different modes of full-thickness macular hole formation.

Full-thickness macular holes (FTMH) are an important cause of visual deterioration. However, different modes of FTMH formation are less investigated. It is also not clear whether the development of edematous cysts contributes to FTMH formation. In this retrospective case series of 30 eyes of 30 patients, we describe using spectral-domain optical coherence tomography different modes of FTMH formation. Morphological alterations of established FTMH are shown in 5 eyes of 5 patients. We found in 2 of 30 eyes investigated that anterior hyaloidal traction induced a hyperreflectivity of the inner Müller cell layer of the foveola prior to FTMH formation. In 3 eyes, FTMH were caused by anterior hyaloidal traction which produced foveal pseudocysts that developed to an outer lamellar hole (OLH) characterized by a disruption of the central outer retina. The OLH developed to a FTMH by the disruption of the inner layer of the foveola. FTMH formation from an OLH by hyaloidal traction was observed also in further 7 eyes. In 2 eyes, the OLH, which preceded FTMH formation, was generated by a serous retinal detachment. In 3 eyes, anterior hyaloidal traction caused a detachment of the fovea from the retinal pigment epithelium (RPE); the subsequent disruption of the foveola resulted in a FTMH. Six eyes showed the development of a FTMH from a degenerative lamellar hole (DLH). In 5 eyes with macular pucker, FTMH were formed by traction of epiretinal membranes (ERM) or hyaloidal traction. Two eyes showed the development of a FTMH by anterior or tangential hyaloidal traction likely without a formation of an OLH. FTMH formation from an OLH proceeded with or without an enlargement of cystic cavities in the foveal walls. The formation of FTMH from a DLH, after a detachment of the fovea, and in macular pucker eyes was associated with a formation of cystic cavities in the foveal walls. The best-corrected visual acuity (BCVA) of eyes with an OLH or FTMH was inversely correlated to the base and minimum diameters of the holes, and with the height of the foveal walls; the highest correlation coefficients were found between the BCVA and the base diameter. The data show that FTMH may be formed via different modes by hyaloidal traction and/or traction of ERM, or after a serous retinal detachment. It is suggested that, after FTMH formation, the impaired fluid clearance through the RPE after detachment of the central outer retina causes the development of edematous cysts in the foveal walls which enlarges the FTMH. The BCVA of eyes with an OLH or FTMH mainly depends on the size of the central photoreceptor-free area.

Neuroprotective effects of glial mediators in interactions between retinal neurons and Müller cells.

Progressive retinal ganglion cell (RGC) loss underlies a number of retinal neurodegenerative disorders, which may lead to permanent vision loss. However, secreted neuroprotective factors, such as PEDF, VEGF and IL-6, which are produced by Müller cells, have been shown to promote RGC survival. Assuming that the communication of RGCs with Müller cells involves a release of glioactive substances we sought to determine whether retinal neurons are able to modulate expression levels of Müller cell-derived PEDF, VEGF and IL-6. We demonstrate elevated mRNA levels of these factors in Müller cells in co-cultures with RGCs or R28 cells when compared to homotypic Müller cell cultures. Furthermore, R28 cells were more protected from apoptosis when co-cultured with Müller cells. IL-6 and VEGF were upregulated in Müller cells under hypoxia. Both cytokines, as well as PEDF, induced an altered neuronal expression of members of the Bcl-2 family, which are central molecules in the regulation of apoptosis. These results suggest that in retinal ischemia, via own secreted mediators, RGCs can resist a potential demise by stimulating Müller cells to increase production of neuroprotective factors, which counteract RGC apoptosis.

Descemet membrane endothelial keratoplasty (DMEK): clinical results of precut versus surgeon-cut grafts.

PURPOSE: This study aims to investigate possible differences in clinical outcomes between precut and surgeon-cut grafts for Descemet membrane endothelial keratoplasty (DMEK). METHODS: 142 consecutive patients who underwent DMEK were included in the study. 44 patients received precut tissues, and 98 patients received surgeon-cut tissues. Precut grafts were allocated to the patient by the German Society for Tissue Transplantation if available. We compared the outcomes of both groups for changes in visual acuity, central corneal thickness, endothelial cell density, re-bubbling rate, and graft failure rate. RESULTS: Patients who received precut tissues experienced similar increase in visual acuity (median change 0.4 logMAR) and decrease of corneal swelling (median change 132 µm) compared with those who received surgeon-cut tissues (median VA change 0.3 logMAR, p = 0.55, CCT change 118 µm, p = 0.63). There was no statistical difference in endothelial cell density (1436 vs. 1569 cells/mm2, p = 0.37), re-bubbling (32% vs. 35%, p = 0.85), and graft failure rate (5% vs. 1%, p = 0.23). No primary graft failure occurred in the group of precut grafts. CONCLUSION: Both methods lead to comparable results for visual acuity, corneal deswelling, endothelial cell density, and re-bubbling rate. A previously described higher graft failure rate for precut tissues could not be confirmed in our study. Thus, we do not see medical reasons against the use of precut tissues. There are several advantages of precut DMEK tissues over surgeon-cut tissues, especially the prevention of graft loss during preparation in the operating theater.

PERSEUS 24-month analysis: a prospective non-interventional study to assess the effectiveness of intravitreal aflibercept in routine clinical practice in Germany in patients with neovascular age-related macular degeneration.

PURPOSE: To evaluate the real-world effectiveness of intravitreal aflibercept injections in Germany in patients with neovascular age-related macular degeneration over 24 months. METHODS: PERSEUS was a prospective, non-interventional cohort study. The primary endpoint was the mean change in visual acuity (VA) from baseline. Secondary endpoints included the proportion of patients with a VA gain or loss of ≥ 15 letters and the frequency of injections and examinations. Patients with regular (bimonthly after 3 monthly injections during year 1 and ≥ 4 injections in year 2) and irregular (any other) treatment were analyzed. The last observation carried forward (LOCF) and the observed cases (OC) approach was applied for primary endpoint analysis to account for missing data. RESULTS: 803 patients were considered for effectivity analysis. At month 24, only 38% of the patients were still under observation. The LOCF population included 727, the OC population 279 patients. Treatment-naïve patients improved by 6.3 (LOCF)/8.1 (OC) letters with regular treatment over 24 months but only by 3.3 (LOCF)/3.1 (OC) letters with irregular treatment. The proportion of treatment-naïve patients achieving a VA improvement of ≥ 15 letters was similar between regularly and irregularly treated cohorts. However, considerably more patients in the irregular cohorts experienced a VA worsening of ≥ 15 letters than in the regular cohorts (LOCF: 18.7% vs. 7.4%). CONCLUSIONS: Regular IVT-AFL treatment resulted in better VA outcomes than irregular treatment at month 24. However, only a minority of patients received regular treatment over a 2-year period.

Importance of continuous treatment with intravitreal aflibercept injections in patients with neovascular age-related macular degeneration-12-month post hoc analysis of the PERSEUS real-world evidence study.

PURPOSE: To investigate the influence of treatment regularity with intravitreal aflibercept injections (IVT-AFL injections) on visual acuity (VA) outcomes in patients with neovascular age-related macular degeneration (nAMD) enrolled in the PERSEUS trial who received at least 7 IVT-AFL injections during the first year. METHODS: This was a post hoc analysis of the PERSEUS trial, a prospective, non-interventional, multicenter cohort study, and included 370 patients with nAMD who had received ≥ 7 IVT-AFL injections during year 1. In addition to the prespecified subgroups of treatment-naïve and previously treated patients, results were compared between patients with regular (n = 209) and irregular (n = 161) treatment. Regular treatment was defined as initial dosing with monthly IVT-AFL injections for 3 months, then bimonthly IVT-AFL injections until month 12. Irregular treatment was defined as any deviation from regular treatment (provided ≥ 7 injections were received). The outcome of primary interest was the mean change in VA from baseline after 12 months. Further outcomes of interest included VA gain or loss, proportion of patients achieving reading vision, and percentage of patients with fluid. RESULTS: At month 12, the mean (± standard deviation, SD) VA improvement from baseline was 6.1 ± 15.6 Early Treatment Diabetic Retinopathy Study letters in the regular cohort and 2.5 ± 16.7 letters in the irregular cohort with ≥ 7 IVT-AFL injections (P = 0.0514). Best results were obtained in the treatment-naïve regular sub-cohort with a mean ± SD VA improvement of 8.0 ± 17.7 letters, whereas treatment-naïve patients with irregular treatment experienced a considerably lower VA gain (2.8 ± 20.0 letters). Irregular treatment consistently correlated with inferior results in treatment-naïve patients. At month 12, the proportion of treatment-naïve patients who had experienced a worsening of ≥ 5 letters was 29.6% in the irregular sub-cohort versus 13.6% in the regular sub-cohort (P = 0.0049). However, among the treatment-naïve patients, the mean number of injections was significantly higher in the irregular than in the regular sub-cohort (8.0 ± 1.2 vs. 7.4 ± 0.6; P = 0.0001). Furthermore, compared with the treatment-naïve, regular sub-cohort, patients in the irregular sub-cohort had more visits (19.1 ± 8.6 vs. 16.1 ± 5.7), VA tests (14.2 ± 6.9 vs. 12.0 ± 4.6), and optical coherence tomography examinations (5.1 ± 3.7 vs. 3.4.0 ± 3.0). CONCLUSIONS: Although irregularly treated patients received more injections and more monitoring visits during the first year of IVT-AFL treatment, they experienced worse VA outcomes than regularly treated patients.

Degenerative lamellar macular holes: tractional development and morphological alterations.

PURPOSE: The development of degenerative lamellar macular holes (DLH) is largely unclear. This study was aimed at documenting with spectral-domain optical coherence tomography the tractional development and morphological alterations of DLH. METHODS: A retrospective case series of 44 eyes of 44 patients is described. RESULTS: The development of DLH is preceded for months or years by tractional deformations of the fovea due to the action of contractile epiretinal membranes (ERM) and/or the partially detached posterior hyaloid, or by cystoid macular edema (CME). DLH may develop after a tractional stretching and thickening of the foveal center, from a foveal pseudocyst, after a detachment of the foveola from the retinal pigment epithelium, a disruption of the foveal structure due to CME, and after surgical treatment of tractional lamellar or full-thickness macular holes (FTMH). The foveal configuration of a DLH can be spontaneously reestablished after short transient episodes of CME and a small FTMH. A DLH can evolve to a FTMH by traction of an ERM. Surgical treatment of a DLH may result in an irregular regeneration of the foveal center without photoreceptors. CONCLUSIONS: Tractional forces play an important role in the development of DLH and in the further evolution to FTMH. It is suggested that a DLH is the result of a retinal wound repair process after a tractional disruption of the Müller cell cone and a degeneration of Henle fibers, to prevent a further increase in the degenerative cavitations.

In vitro drusen model - three-dimensional spheroid culture of retinal pigment epithelial cells.

Age-related macular degeneration (AMD) is a leading cause of blindness in people over 50 years of age in many developed countries. Drusen are yellowish extracellular deposits beneath retinal pigment epithelium (RPE) found in aging eyes and considered as a biomarker of AMD. However, the biogenesis of drusen has not been elucidated. We reported previously that multicellular spheroids of human RPE cells constructed a well-differentiated monolayer of RPE with a Bruch's membrane. We determined that RPE spheroids exhibited drusen formation between the RPE and Bruch's membrane with expression of many drusen-associated proteins, such as amyloid ß and complement components, the expression of which was altered by a challenge with oxidative stress. Artificial lipofuscin-loaded RPE spheroids yielded drusen more frequently. In the current study, we showed that drusen originates from the RPE. This culture system is an attractive tool for use as an in vitro drusen model, which might help elucidate the biogenesis of drusen and the pathogenesis of related diseases, such as AMD.

Osmotic regulation of aquaporin-8 expression in retinal pigment epithelial cells in vitro: Dependence on KATP channel activation.

Purpose: The expression of aquaporin-8 (AQP8), which plays a crucial role in the maintenance of the cellular fluid and electrolyte balance, was shown to be increased in RPE cells under hyperosmotic conditions. The aim of the present study was to investigate the mechanisms of hyperosmotic AQP8 gene expression and the localization of AQP8 in cultured human RPE cells. Methods: Hyperosmolarity was produced with the addition of 100 mM NaCl or 200 mM sucrose. Hypoxia was induced by cell culture in a 0.2% O2 atmosphere or the addition of the hypoxia mimetic CoCl2. Oxidative stress was induced by the addition of H2O2. Gene expression was determined with real-time RT-PCR analysis. AQP8 protein localization and secretion of VEGF were evaluated with immunocytochemistry, western blotting, and enzyme-linked immunosorbent assay (ELISA). Results: Immunocytochemical and western blot data suggest that the AQP8 protein is mainly located in the mitochondria. Extracellular hyperosmolarity, hypoxia, and oxidative stress induced increases in AQP8 gene expression. Hyperosmotic AQP8 gene expression was reduced by inhibitors of the p38 MAPK and PI3K signal transduction pathways, and by JAK2 and PLA2 inhibitors, and was in part mediated by the transcriptional activity of CREB. Hyperosmotic AQP8 gene expression was also reduced by autocrine/paracrine interleukin-1 signaling, the sulfonylureas glibenclamide and glipizide, which are known inhibitors of KATP channel activation, and a pannexin-blocking peptide. The KATP channel opener pinacidil increased the expression of AQP8 under control conditions. The cells contained Kir6.1 and SUR2B gene transcripts and displayed Kir6.1 immunoreactivity. siRNA-mediated knockdown of AQP8 caused increases in hypoxic VEGF gene expression and secretion and decreased cell viability under control, hyperosmotic, and hypoxic conditions. Conclusions: The data indicate that hyperosmotic expression of AQP8 in RPE cells is dependent on the activation of KATP channels. The data suggest that AQP8 activity decreases the hypoxic VEGF expression and improves the viability of RPE cells which may have impact for ischemic retinal diseases like diabetic retinopathy and age-related macular degeneration.

Osmotic and hypoxic induction of osteopontin in retinal pigment epithelial cells: Involvement of purinergic receptor signaling.

Purpose: Osteopontin (OPN) is a neuroprotective factor in the retina that improves photoreceptor survival. The aim of the present study was to investigate whether human RPE cells express and respond to OPN. Methods: Hypoxia and chemical hypoxia were induced by cell culture in 0.25% O2 and the addition of CoCl2, respectively. Hyperosmolarity was produced by the addition of 100 mM NaCl or 200 mM sucrose. Gene expression was quantified with real-time reverse transcription (RT)-PCR, and protein secretion was investigated with enzyme-linked immunosorbent assay (ELISA). Nuclear factor of activated T cell 5 (NFAT5) was depleted with siRNA. Results: The acutely isolated RPE cells and the cultured RPE cells expressed OPN. OPN gene expression was induced by hypoxia and hyperosmotic media, as well as by exogenous bFGF. High extracellular NaCl and hypoxia induced secretion of OPN. Hyperosmotic expression of the OPN gene was mediated by the p38 MAPK and ERK1/2 signal transduction pathways, and the transcriptional activities of CREB and NFAT5. The hypoxic expression of the OPN gene was mediated by the PI3K signal transduction pathway and caspase-mediated, necrosis-related pathways. Phospholipases A2 were involved in mediating hyperosmotic and hypoxic OPN gene expression. Autocrine or paracrine P2Y2 receptor signaling induced by extracellular ATP contributed to hyperosmotic expression of the OPN gene whereas activation of A1 receptors by extracellularly formed adenosine contributed to thypoxic OPN gene expression. Autocrine or paracrine VEGF signaling exerted an inhibitory effect on expression of the OPN gene. Exogenous OPN induced expression and secretion of bFGF, but not of VEGF. Conclusions: The data indicated that RPE cells produce and respond to OPN; OPN expression is, in part, induced by the cellular danger signal ATP. RPE-derived neuroprotective factors such as bFGF may contribute to the prosurvival effect of OPN on photoreceptor cells.

Pigment Epithelium-Derived Factor (PEDF) Receptors Are Involved in Survival of Retinal Neurons.

The demise of retinal ganglion cells (RGCs) is characteristic of diseases of the retina such as glaucoma and diabetic or ischemic retinopathies. Pigment epithelium-derived factor (PEDF) is a multifunctional secreted protein that mediates neuroprotection and inhibition of angiogenesis in the retina. We have studied expression and regulation of two of several receptors for PEDF, patatin-like phospholipase 2 gene product/PEDF-R and laminin receptor (LR), in serum-starved RGC under normoxia and hypoxia and investigated their involvement in the survival of retinal neuronal cells. We show that PEDF-R and LR are co-expressed in RGC and R28 retinal precursor cells. Expression of both receptors was enhanced in the presence of complex secretions from retinal glial (Müller) cells and upregulated by VEGF and under hypoxic conditions. PEDF-R- and LR-knocked-down cells demonstrated a markedly attenuated expression of anti-apoptotic Bcl-2 family members (Bcl-2, Bcl-xL) and neuroprotective mediators (PEDF, VEGF, BDNF) suggesting that both PEDF-R and LR mediate pro-survival effects of PEDF on RGC. While this study does not provide evidence for a differential survival-promoting influence of either PEDF-R or LR, it nevertheless highlights the importance of both PEDF receptors for the viability of retinal neurons.

Two different populations of Müller cells stabilize the structure of the fovea: an optical coherence tomography study.

PURPOSE: To document with spectral-domain optical coherence tomography the structural stabilization of the fovea and the sealing of outer macular defects by Müller cells. METHODS: A retrospective case series of 45 eyes of 34 patients is described. RESULTS: In cases of a cystic disruption of the foveola as in macular telangiectasia type 2 and vitreomacular traction, the Müller cell cone provides the structural stability of the fovea. In cases of a detachment or disruption of the Müller cell cone, e.g., in foveal pseudocysts, outer lamellar holes, and degenerative and tractional lamellar holes, Müller cells of the foveal walls may provide the structural stability of the fovea by the formation of a hyperreflective external limiting membrane (ELM) which bridges the holes in the central outer nuclear layer (ONL). Müller cells of the foveal walls and parafovea mediate the regeneration of the foveal architecture in cases of outer lamellar and full-thickness macular holes. The regeneration proceeds by a centripetal displacement of photoreceptor cell somata which closes the holes in the central ONL. The closure may be supported by the formation of a glial tissue band at the ELM which seals the hole. CONCLUSIONS: The Müller cell cone provides the foveal stability in cases of a cystic disruption of the foveola. The structural stability of the outer foveal layers is mainly provided by the Müller cells of the foveal walls and parafovea; these cells also mediate the regeneration of the outer fovea in cases of a defect of the central ONL.