Differential expression of vascular endothelial growth factor-a isoforms in neovascular age-related macular degeneration.

PURPOSE: To investigate the role of vascular endothelial growth factor-A (VEGF-A) isoforms in neovascular age-related macular degeneration. METHODS: Choroidal neovascular membranes (CNV) were excised in 24 patients, 8 of them underwent previous photodynamic therapy. All procedures were performed before anti-VEGF therapies were implemented in Germany. Normal human donor eyes served as controls. Messenger RNA expression of total VEGF-A and VEGF-A isoforms was measured. RESULTS: Vascular endothelial growth factor-A121 is the most abundant isoform in CNV and control tissues. In controls, VEGF-A121 is lowest in neural retina and highest in choroids. For total VEGF-A and VEGF-A165, this is vice versa. VEGF-A165 and VEGF-A189 are significantly higher in CNV than in control choroids, the opposite is found for VEGF-A121. After photodynamic therapy, total VEGF-A and VEGF-A121 are increased, VEGF-A165 and VEGF-A189 are decreased. Age-dependently, there is an increase in VEGF-A165 and a decrease in VEGF-A121. CONCLUSION: Vascular endothelial growth factor-A isoforms are differentially distributed, suggesting that tissue-specific regulation of various isoforms is physiologically important. The disruption of this homeostasis in CNV membranes may be significant in the onset and progression of neovascular age-related macular degeneration. Our findings support the dominant role of VEGF-A121 in neovascular age-related macular degeneration but hint that VEGF-A165 may have an equivalent role in other neovascular retinal pathology.

Comparing the effects of two different irrigation solutions on an isolated perfused vertebrate retina.

PURPOSE: To compare the effect of a taurine-containing intraocular irrigation solution (PuriProtect TM) to a standard irrigation solution (BSS TM) we evaluated the retinal function using an electroretinogram (ERG) and analyzed the survival of retinal ganglion cells on isolated whole mount retinas. MATERIALS AND METHODS: During ERG recordings, each irrigation solution was superfused for 45 min with the relevant irrigation solution. To investigate the effects on photoreceptor function, 1 m M asparate was added to obtain a-waves.The recovery of the a- and b-wave was monitored after superfusing the retinas with standard medium again. To evaluate the percentage of dead ganglion cells, retinas were stored for 24 h at 4°C in darkness and after staining the retinas with ethidium homodimer-1 the retinas were analyzed using fluorescence microscopy. RESULTS: The application of standard medium supplemented with 2 m M taurine resulted in a significant increase of the b-wave amplitude compared to standard medium alone. The a-wave amplitudes showed no significant changes under taurine supplementation. Compared to standard medium BSS showed no significant decrease in b-wave amplitudes, but a significant decrease ina-wave amplitudes. In contrast to BSS there were no significant changes in the a- or b-wave amplitudes detectable after the application of PuriProtect. At the end of the washout period no significant changes in a- or b-wave amplitudes were recorded for any tested irrigation solution. Retinas stored for 24 h in PuriProtect or in standard medium with taurine had a statistically significant smaller amount of dead cells than retinas stored in standard medium without taurine supplementation. CONCLUSIONS: BSS does not seem to be an ideal irrigation solution, because it compromises the a-wave in the ERG. In contrast to BSS, PuriProtect showed no significant impact on the ERG and showed a better long-term effect on ganglion cell survival. Taurine supplementation,therefore, seems to be neuroprotective and its supplementation to an intraocular irrigation solution favorable for the retina.

The effects of the intraocular dye brilliant blue G (BBG) mixed with varying concentrations of glucose on retinal function in an isolated perfused vertebrate retina.

BACKGROUND: During vitreoretinal surgery, vital dyes such as brilliant blue G (BBG) are used to visualize anatomical structures. By adding glucose to a concentration of 5%, many surgeons try to achieve a dye mixture heavier than water to facilitate staining of the ILM without preceding fluid-air exchange. However, the intraocular use of high glucose concentrations is critical. This study investigated the effect of 0.4 ml BBG (Brilliant Peel™ 0.25 mg/ml, Fluoron, Ulm, Germany) mixed with various glucose concentrations on the retina in an pseudo in vivo model METHODS: Bovine retinas were isolated and superfused with an oxygen saturated nutrient solution, and the electroretinogram (ERG) was recorded. BBG mixed with 0.05 ml/0.1 ml/0.15 ml glucose 40% was applied epiretinally. ERG recovery was monitored for 75 minutes. 1 mM aspartate was added to the nutrient solution to obtain a-waves. RESULTS: After application of BBG/0.05 ml 40% glucose, a non-significant decrease of the b-wave amplitude was recorded (11.2%). In contrast, higher glucose concentrations showed a significant decrease of the b-wave (23.40% at 0.1 ml glucose, 26% at 0.15 ml glucose). The a-wave amplitudes showed no significant change at the end of the washout for all concentrations. CONCLUSIONS: The clinically used mixture of BBG and glucose seems to be safe up to a concentration of 5%. However, higher concentrations of glucose starting from 10% showed strong evidence of a toxic effect on the retinal function and should be avoided.

Papillary capillary activation in Terson syndrome.

We report the immunopathology and histopathology of a patient with Terson syndrome. The design was an observational case-report. Histopathology and immunohistochemical staining for endoglin (CD105) of an eye from a patient with subarachnoid haemorrhage and Terson syndrome was performed. Immunohistology revealed high papillary endoglin expression. Up-regulation of endoglin indicates activation of endothelial cells. This may suggest a regeneration process after the acute insult.

Systematic evaluation of ICG and trypan blue related effects on ARPE-19 cells in vitro.

The aim of our study was a systematic analysis of the impact of variable parameters on indocyanine green (ICG) and trypan blue (TB) related cytotoxicity on human RPE cells. ARPE-19 cells were incubated with ICG (5.0-0.025mg/ml), with ICG-free solutions of corresponding osmolarities or with TB (1.5-0.0375mg/ml). Incubation lasted 1-20min with or without endolight illumination for 1min or 5min. Cell viability and morphology were examined after 6h, 24h and 72h to detect acute and delayed effects. In the absence of endolight, ICG cytotoxicity depends on osmolarity and exposure time. In the presence of endolight, cytotoxic effects are influenced by dye concentration. TB cytotoxicity depends on dye concentration and exposure time, but not on illumination. All observed cytotoxic effects were mainly acute. Both ICG and TB can be cytotoxic depending on concentration and exposure time. ICG related cytotoxic effects are additionally determined by osmolarity and phototoxicity. However, concentrations (<1mg/ml) and incubation times (<5min) as used in clinical practice would appear to be well tolerated.