Limitations in assessing nerve growth factor levels in aqueous humor samples from human eyes

<p>Abstract</p> <p>Background</p> <p>Nerve growth factor (NGF) helps in the healing and survival of ganglion cells, photoreceptors, and optic nerve after injury and has been implicated to have a role in pathophysiology of glaucoma. So far, in animal studies, injury to iris in vitro has revealed an increase in NGF levels in aqueous. There is a great interest in investigating the levels of NGF in human aqueous in glaucomatous eyes, as suggested by animal studies, to gain a better understanding of the pathophysiology of glaucoma.</p> <p>Findings</p> <p>In this study, we examined the presence of NGF levels in aqueous humor collected from human eyes and the limitations in determining the NGF levels in human samples. NGF was assessed by ELISA immunoassay in undiluted aqueous samples collected from 32 consecutive patients undergoing surgery for cataract (control) or primary open angle glaucoma (POAG). Recombinant NGF was used as positive control. NGF levels were below undetectable levels in aqueous humor from eyes with POAG and controls by immunoassay. Less than 10% of samples had detectable NGF levels and these were considered outliers.</p> <p>Conclusion</p> <p>Our result highlights the undetectable levels of NGF in human aqueous samples.</p

Functional microperimetry and SD-OCT confirm consecutive retinal atrophy from optic nerve pit

A congenital anomaly, optic nerve pit is often associated with serous retinal detachment involving macula. Long standing serous detachment leads to outer retinal atrophy and decrease in visual sensitivity. Recently, spectral-domain optical coherence tomography (OCT) has been reported to demonstrate a communication between the optic nerve sheath and the subretinal space. Vitreous cavity is proposed as an alternate source of fluid for accumulation in the subretinal space. We imaged a patient with optic nerve pit with Spectralis OCT and report the findings seen including the presence of an area of peripapapillary retinal atrophy, due to the spontaneous resolution of associated long-standing retinal detachment

Freezing adversely affects measurement of vascular endothelial growth factor levels in human aqueous samples

Sankarathi Balaiya Sandeep Grover Ravi K Murthy Kakarla V ChalamDepartment of Ophthalmology, University of Florida College of Medicine, Jacksonville, FL, USAPurpose: Aqueous levels of vascular endothelial growth factor (VEGF) can be a surrogate marker of intraocular VEGF activity and a measure of efficacy of anti-VEGF treatment in a variety of vasoproliferative retinal disorders, including diabetic retinopathy, age-related macular degeneration, and central retinal vein occlusion. Measurement of the VEGF level may be adversely affected by premeasurement variables, such as freezing and delay, in sample analysis. We aim to evaluate the effect of storage and delayed measurement of human aqueous VEGF levels in these conditions.Methods: Aqueous samples collected from patients receiving intravitreal injection of bevacizumab for various retinal diseases were divided into two groups. In Group 1, the VEGF levels were analyzed on the same day; in Group 2, the VEGF levels were analyzed after 21 days of freezer storage (-80&amp;deg;C) using immunobead assay. Statistical comparison using a paired t-test was performed between the two groups.Results: Thirty-one aqueous humor samples were collected, and the VEGF concentration for fresh samples was 7.8 &amp;plusmn; 5.9 pg/mL (mean &amp;plusmn; SD) compared to 6.5 &amp;plusmn; 6.0 pg/mL in frozen samples, resulting in a statistically significant difference (P = 0.03).Conclusions: Accurate measurement of the VEGF level is a vital component of clinical decision-making. Delayed analysis of VEGF levels in aqueous samples may result in significant sample degradation and lower levels of measured VEGF.Keywords: VEGF level, aqueous humor, immunobead assay, VEGF storag

Effects of Indocyanine green on cultured retinal ganglion cells in-vitro

<p>Abstract</p> <p>Background</p> <p>Indocyanine green (ICG) dye is commonly used to stain the inner limiting membrane during macular surgery. There are reports documenting the toxicity of ICG on retinal pigment epithelial cells, with conflicting results in retinal ganglion cells. In the present study, we evaluated the effect of ICG on retinal ganglion cells in vitro.</p> <p>Cultured rat retinal ganglion cells (RGC-5) were exposed to different concentrations of ICG (0.25, 0.5, 1.0, 1.25, & 5 mg/ml) and at various time intervals (1, 5, 15, 30, & 60 minutes). Changes in structural morphology were identified using phase contrast bright field microscopy. Cell viability was quantified using the neutral red assay and cell death was characterized using Annexin-V staining.</p> <p>Findings</p> <p>Significant morphologic changes were observed at the 15 and 60 min intervals for all concentrations, where a reduction in cell size and loss of normal spindle shape was noted. A dose dependent decrease in cell viability was observed with increasing concentration of ICG as well as increasing exposure intervals. Compared to control, 48-74% reduction in neutral red uptake at all concentrations for exposures 5 min or greater (p < 0.001). Even at 1 min exposure, a dose dependent decline was observed in cell viability, with a 28-48% decline for doses above 1.25 mg/ml (p = 0.007). Staining with Annexin-V, demonstrated a similar dose and time dependent increase in number of cells exhibiting early apoptosis. A greater than two-fold increase in Annexin-V expression for all doses at exposures greater than 1 min was noted.</p> <p>Conclusion</p> <p>ICG dye exhibits toxicity to retinal ganglion cells at clinically relevant doses following 1 min exposure.</p