Optic Ganglion Cells Research Articles

Retinal Structure of Poecilia sphenops: Photoreceptor Mosaics, Synaptic Ribbon Patterns, and Glial Cell Expressions.

The specific arrangement and distribution of photoreceptors in the retina can vary among different fish species, with each species exhibiting adaptations related to its habitat, behavior, and visual requirements. Poecilia sphenops, a diurnal fish, was the focus of this study. The retinas of a total of eighteen Molly fish were investigated utilizing light and electron microscopy. The retina exhibited a square mosaic pattern of the inner segments of cones. This pattern comprised double cones positioned along the sides of a square, with two types of single cones situated at the center and corners of the square arrangement across the entire retina. The corner cones were slightly shorter than the central ones. Additionally, the outer plexiform layer contained both cone pedicles and rod spherules. The rod spherule consisted of a single synaptic ribbon arranged in a triad or quadrat junctional arrangement within the invaginating free ends of the horizontal and bipolar cell processes. On the other hand, cone pedicles have more than one synaptic ribbon in their junctional complex. The inner nuclear layer consisted of the amacrine, bipolar, Müller, and horizontal cell bodies. Müller cell processes, expressing GFAP, extended across all retinal layers, segmenting the deeper retina into alternating fascicles of optic axons and ganglion cells. The outer and inner plexiform layers showed many astrocyte cell processes expressing GFAP. In conclusion, the current study is the first record of the retinal structures of Molly fish. This study illustrated the mosaic arrangement of photoreceptors and GFAP expression patterns of astrocytes and Müller cells. The presence of three cone types, coupled with a sufficient number of rods, likely facilitates motion awareness for tasks like finding food and performing elaborate mating ceremonies.

Small extracellular vesicles derived from human induced pluripotent stem cell-differentiated neural progenitor cells mitigate retinal ganglion cell degeneration in a mouse model of optic nerve injury.

JOURNAL/nrgr/04.03/01300535-202502000-00034/figure1/v/2024-05-28T214302Z/r/image-tiff Several studies have found that transplantation of neural progenitor cells (NPCs) promotes the survival of injured neurons. However, a poor integration rate and high risk of tumorigenicity after cell transplantation limits their clinical application. Small extracellular vesicles (sEVs) contain bioactive molecules for neuronal protection and regeneration. Previous studies have shown that stem/progenitor cell-derived sEVs can promote neuronal survival and recovery of neurological function in neurodegenerative eye diseases and other eye diseases. In this study, we intravitreally transplanted sEVs derived from human induced pluripotent stem cells (hiPSCs) and hiPSCs-differentiated NPCs (hiPSC-NPC) in a mouse model of optic nerve crush. Our results show that these intravitreally injected sEVs were ingested by retinal cells, especially those localized in the ganglion cell layer. Treatment with hiPSC-NPC-derived sEVs mitigated optic nerve crush-induced retinal ganglion cell degeneration, and regulated the retinal microenvironment by inhibiting excessive activation of microglia. Component analysis further revealed that hiPSC-NPC derived sEVs transported neuroprotective and anti-inflammatory miRNA cargos to target cells, which had protective effects on RGCs after optic nerve injury. These findings suggest that sEVs derived from hiPSC-NPC are a promising cell-free therapeutic strategy for optic neuropathy.

BAFF deficiency aggravated optic nerve crush-induced retinal ganglion cells damage by regulating apoptosis and neuroinflammation via NF-κB-IκBα signaling

Loss of retinal ganglion cells (RGCs) is a primary cause of visual impairment in glaucoma, the pathological process is closely related to neuroinflammation and apoptosis. B-cell activating factor (BAFF) is a fundamental survival factor mainly expressed in the B cell lineage. Evidence suggests its neuroprotective effect, but the expression and role in the retina have not yet been investigated. In this study, we adopt optic nerve crush (ONC) as an in vivo model and oxygen-glucose deprivation/reoxygenation (OGD/R) of RGCs as an in vitro model to investigate the expression and function of BAFF. We found that BAFF and its receptors were abundantly expressed in the retina and BAFF inhibition exacerbated the caspase 3-mediated RGCs apoptosis, glial cell activation and pro-inflammatory cytokines expression, which may be caused by the activation of the NF-κB pathway in vivo. In addition, we found that BAFF treatment could alleviate RGCs apoptosis, pro-inflammatory cytokines expression and NF-κB pathway activation, which could be reversed the effect by blockade of the NF-κB pathway in vitro. Meanwhile, we found that microglia induced to overexpress BAFF in the inflammatory microenvironment in a time-dependent manner. Taken together, our results indicated that BAFF deficiency promoted RGCs apoptosis and neuroinflammation through activation of NF-κB pathway in ONC retinas, suggesting that BAFF may serve as a promising therapeutic target for the treatment of glaucoma.

Lycii Fructus, a medicine food homology material, attenuates retinal damage in sodium iodate-induced retinal degeneration mice and inhibits oxidation-induced apoptosis of Müller cells via regulating Nrf2-HO1 signaling pathway

Lycii Fructus (LF) is a medicinal-edible homology material frequently used for treating age-related macular degeneration (AMD) in Chinese medicine. Abundant of literatures verified the retina protection effect of LF on AMD-like animal models. However, previous studies on LF attenuating retinal damage mainly focused on its protection effect on pigment epithelial cells and optic ganglion cells while few reports on Müller cells. In the current study, we found that LF extracts attenuated oxidation damages and inhibited cell apoptosis of retina on a mouse retinal injury model induced by sodium iodate. LF extracts also increased expressions of Müller cell biomarker glutamine synthetase of eyeballs of model mice, which indicated that LF extract protected Müller cell from oxidation injury induced by sodium iodate. In Müller cell MIO-M1 cultures, LF also significantly inhibited cellular apoptosis induced by NaIO3 by regulating Nrf2/HO-1 signaling pathway and the aqueous extracts exerted better active tendency than ethanol extracts. These data implied that the antioxidant effect of LF on protecting Müller cell might contribute to its retina repair function, thereby providing more scientific evidences for the development of LF as an alternative therapy or preventive measures for AMD.

The Importance of Optical Coherence Tomography in the Diagnosis of Atypical or Subclinical Optic Neuritis: A Case Series Study

Background: Optic neuritis (ON) is an inflammatory condition of the optic nerve. ON is associated with development of demyelinating diseases of the central nervous system (CNS). CNS lesions visualized by magnetic resonance imaging (MRI) and the finding of oligoclonal IgG bands (OB) in the cerebrospinal fluid (CSF) are used to stratify the risk of MS after a "first" episode of ON. However, the diagnosis of ON in absence of typical clinical manifestations can be challenging. Methods and Materials: Here we present three cases with changes in the optic nerve and ganglion cell layer in the retina over the disease course. (1) A 34-year-old female with a history of migraine and hypertension had suspect amaurosis fugax (transient vision loss) in the right eye. This patient developed MS four years later. Optical coherence tomography (OCT) showed dynamic changes of the thickness of peripapillary retinal nerve fiber layer (RNFL) and macular ganglion cell-inner plexiform layer (GCIPL) over time. (2) A 29-year-old male with spastic hemiparesis and lesions in the spinal cord and brainstem. Six years later he showed bilateral subclinical ON identified using OCT, visual evoked potentials (VEP) and MRI. The patient fulfilled diagnosis criteria of seronegative neuromyelitis optica (NMO). (3) A 23-year-old female with overweight and headache had bilateral optic disc swelling. With OCT and lumbar puncture, idiopathic intracranial hypertension (IIH) was excluded. Further investigation showed positive antibody for myelin oligodendrocyte glycoprotein (MOG). Conclusions: These three cases illustrate the importance of using OCT to facilitate quick, objective and accurate diagnosis of atypical or subclinical ON, and thus proper therapy.

Altered dynamic functional connectivity in the primary visual cortex in patients with primary angle-closure glaucoma.

Glaucoma is the main blindness-causing disease in the world. Previous neuroimaging studies demonstrated that glaucoma not only causes the loss of optic ganglion cells but also leads to the abnormal function of the optic nerve pathway and the visual cortex. However, previous studies also reported that patients with glaucoma have dysfunction in the visual cortex in a static state. Whether or not patients with primary angle-closure glaucoma (PACG) were accompanied by dynamic functional connectivity (FC) changes in the primary visual cortex (V1) remains unknown. A total of 34 patients with PACG (23 men and 11 women) and 34 well-matched healthy controls (HCs) were enrolled in the study. The dynamic functional connectivity (dFC) with the sliding window method was applied to investigate the dynamic functional connectivity changes in the V1. Compared with HCs, patients with PACG showed increased dFC values between left V1 and bilateral calcarine (CAL). Meanwhile, patients with PACG showed increased dFC values between right V1 and bilateral CAL. Our study demonstrated that patients with PACG showed increased dFC within the visual network, which might indicate the increased variability FC in the V1 in patients with PACG.

Optic disc, macula and ganglion cell layer measurements obtained with optical coherence tomography in patients with thyroid disorder

Purpose: The aim of this study was to compare retinal nerve layer thickness, central macula thickness and ganglion cell layer measurements using optical coherence tomography (OCT) between thyroid patients and age- and sex-matched healthy controls.
 Materials and Methods: Eighty eyes of 80 patients in the thyroid patient group and 48 eyes of 48 patients in the control group were included in the study. After evaluating the exclusion criteria, visual acuity, anterior segment biomicroscopy, intraocular pressure, fundoscopy and spectral field optic coherence tomography (SF-OCT) imaging tests were performed on all patients included in the study. These data have been recorded. Central macular thickness (CMT), retinal nerve fiber layer (RNFL) and ganglion cell complex (GCC) measurements were evaluated by statistical methods for both groups.
 Results: There was no statistically significant difference between the demographic data of the groups included in the study. IOP measurements were found to be statistically significantly higher in the patient group compared to the control group. CMT values were 258.2±16.1 µm in the patient group and 273.1±23.8 µm in the control group, and statistically significant differences were observed between the groups. 
 Conclusion: The findings supports that changes in the optic nerve and macula develop before vision loss in TO patients compared to the healthy control group. We can follow TO patients more objectively and reliably and make treatment planning more accurately by adding OCT, which is a noninvasive test, to our clinical practice, since structural changes develop before functional deterioration in TO patients.

Comprehensive visual electrophysiological measurements discover crucial changes caused by alcohol addiction in humans: Clinical values in early prevention of alcoholic vision decline.

Alcohol addiction often compromises vision by impairing the visual pathway, particularly the retina and optic nerve. Vision decline in alcoholics consists of a sequential transition from reversible functional deterioration of the visual pathway to irreversible clinical vision degeneration or vision loss. Thus, the control of alcoholic vision decline should focus on prevention before permanent damage occurs. Visual electrophysiology is a promising method for early detection of retinal dysfunction and optic neuropathy, including full-field electroretinography (ffERG) and pattern-reversal visual evoked potential (PR-VEP). So far, however, research studying the electrophysiological characteristics in the preclinical stage of vision decline caused by alcohol addiction is still lacking. Here we conducted a retrospective study with 11 alcoholics and 14 matched control individuals to address this need. We had performed comprehensive visual electrophysiological tests, including ffERG and PR-VEP. We next analyzed all electrophysiological parameters using multivariate statistical analyses and discovered some highly sensitive alterations to alcohol addiction. We found severely reduced amplitudes in scotopic ffERG oscillatory potentials (OPs) in alcohol addicts. These changes indicate the alcohol-induced disturbances of amacrine cells and retinal circulation. In subjects with alcohol addiction, the amplitudes of b-waves diminish significantly in scotopic but not photopic ffERG, implying the impaired function of the retinal rod system and the dysfunction of the inner retina. PR-VEPs elicited by checkerboard stimuli with large 1 degree (°) checks mainly reflect the state of the optic nerve and ganglion cells, and PR-VEPs provoked by small 0.25° checks mainly reflect the function of the macular. We performed both measurements and observed a robust amplitude reduction in all three peaks (N75–P100, P100–N135) and a significant peak time extension in P100. Our research provides an affordable and non-invasive tool to accurately evaluate visual pathway conditions in alcohol addicts and help clinicians take targeted treatment.

CD82 protects against glaucomatous axonal transport deficits via mTORC1 activation in mice

Glaucoma is a leading cause of irreversible blindness worldwide and is characterized by progressive optic nerve degeneration and retinal ganglion cell loss. Axonal transport deficits have been demonstrated to be the earliest crucial pathophysiological changes underlying axonal degeneration in glaucoma. Here, we explored the role of the tetraspanin superfamily member CD82 in an acute ocular hypertension model. We found a transient downregulation of CD82 after acute IOP elevation, with parallel emergence of axonal transport deficits. The overexpression of CD82 with an AAV2/9 vector in the mouse retina improved optic nerve axonal transport and ameliorated subsequent axon degeneration. Moreover, the CD82 overexpression stimulated optic nerve regeneration and restored vision in a mouse optic nerve crush model. CD82 exerted a protective effect through the upregulation of TRAF2, which is an E3 ubiquitin ligase, and activated mTORC1 through K63-linked ubiquitylation and intracellular repositioning of Raptor. Therefore, our study offers deeper insight into the tetraspanin superfamily and demonstrates a potential neuroprotective strategy in glaucoma treatment.

The Lack of Amyloidogenic Activity Is Persistent in Old WT and APPswe/PS1ΔE9 Mouse Retinae.

We have previously reported that vision decline was not associated with amyloidogenesis processing in aging C57BL/6J wild-type (WT) mice and in a mouse model of Alzheimer’s disease, the APPswe/PS1ΔE9 transgenic mouse model (APP/PS1). This conclusion was drawn using middle-aged (10–13 months old) mice. Here, we hypothesized that compared with hippocampal and cortical neurons, the weak amyloidogenic activity of retinal neurons may result in a detectable release of amyloid β (Aβ) only in aged mice, i.e., between 14 and 24 months of age. The aim of the present study was thus to follow potential activity changes in the amyloidogenic and nonamyloidogenic pathways of young (4 months) and old (20–24 months) WT and APP/PS1 mice. Our results showed that in spite of retinal activity loss reported by electroretinogram (ERG) recordings, the level of amyloid beta precursor protein (APP) and its derivatives did not significantly vary in the eyes of old vs. young mice. Strikingly, the ectopic expression of human APPswe in APP/PS1 mice did not allow us to detect Aβ monomers at 23 months. In contrast, Aβ was observed in hippocampal and cortical tissues at this age but not at 4 months of life. In contrast, optic nerve transection-induced retinal ganglion cell injury significantly affected the level of retinal APP and the secretion of soluble APP alpha in the vitreous. Collectively, these results suggest that the amyloidogenic and nonamyloidogenic pathways are not involved in visual function decline in aging mice. In WT and APP/PS1 mice, it is proposed that retinal neurons do not have the capacity to secrete Aβ in contrast with other cortical and hippocampal neurons.

Клинический случай впервые выявленной далекозашедшей первичной открытоугольной глаукомы на фоне друз диска зрительного нерва

Aim. To present a clinical case of glaucoma development against the background of optic disc drusen (ODD), demonstrating the difficulties of differential diagnosis between such nosologies as glaucomatous optic neuropathy, optic disc swelling, and chronic optic neuropathy caused by ODD. Methods. Patient S., 72 years old, was referred to clinic with suspected optic disc swelling, initial senile cataract of both eyes. The patient underwent additional investigations: Maklakov tonometry registered an increase of intraocular pressure level exceeding permissible norm; perimetry which has revealed narrowing of visual field boundaries in both eyes; ß-scan ultrasonography has visualized morphological changes with highly reflective drusen in both eyes; optical coherence tomography of optic nerve and ganglion cell layer revealed decrease in nerve fiber layer thickness on nasal side. For differential diagnosis, the patient underwent magnetic resonance imaging (MRI) of the brain, according to which intracranial pathology was excluded. Results. Using modern diagnostic methods it was possible to establish clinical diagnosis: newly detected primary open-angle glaucoma (POAG) III b, explicit ODD, initial senile cataract, pseudoexfoliation syndrome grade 2. Hypotensive regimen did not result in target pressure; therefore, the patient was prescribed surgical treatment (microinvasive non-penetrating deep sclerectomy on both eyes). Conclusion. The presented clinical case showed that against the background of ODD creating the picture of pseudo-swelling and masking the changes in optic nerve because of glaucoma process, the patient had POAG in far-advanced stage. MRI of the brain, as well as additional ophthalmological investigations using modern technologies, made it possible to establish correct diagnosis and prescribe the necessary therapy for this nosology. Key words: optic disc drusen; primary open-angle glaucoma; perimetry; optical coherence tomography.

On the Protective Effect of Lycium Barbarum Polysaccharide (LBP) on Optic Nerve Tissue and Retinal Ganglion Cells

Background: The present paper established a model of optic neuritis injury by intrathecal injection of lipopolysaccharide (LPS) into the optic nerve, then explored the protective effect of Lycium Barbarum Polysaccharide (LBP) on optic nerve tissue and RGCs after injury. Material and methods: LPS was microinjected into the optic nerve of SD rats to induce optic neuritis. The histopathological variations of HE staining were observed in each group. The expressions of ED1/CD68 and GFAP were determined by immunofluorescence. The optic nerve repairment was evaluated by lux solid blue staining. TUNEL detects retinal cell apoptosis. Western blot was used to detect differences in expressions of related proteins. Results: LBP can alleviate the degree of optic nerve damage in rats with optic neuritis injury, inhibit the increase of LPS-induced macrophages and astrocytes in the optic nerve and retina, mitigate LPS-induced retinal RGC damage, inhibit LPS-induced expressions of proinflammatory cytokines TNF-α and IL-6, COX2 and iNOS in the optic nerve injury model of optic neuritis in rats, as well as inhibit the activation of STAT1, STAT3 and NF-κB pathways. Conclusion: LBP can ameliorate optic nerve damage, and the mechanism may be realized through inhibiting NF- B and STAT signaling pathways.

Relationship between miR-375 regulating Ndrg2/IL-6/STAT3 signaling pathway and diabetic retinopathy in rats.

To explore the relationship between micro ribonucleic acid (miR)-375 in regulating the N-Myc downstream-regulated gene 2 (Ndrg2)/interleukin-6 (IL-6)/signal transducer and activator of transcription 3 (STAT3) signaling pathway and diabetic retinopathy (DR) in rats. Thirty Sprague- Dawley rats were randomly divided into Control group (n=10), Model group (n=10), and miR-375 inhibitor group [miR-375 small interfering RNA (siRNA) group, n=10]. The rats in Model group were injected with streptozotocin (STZ) via the tail vein to prepare into rat models of diabetes. The body weight, fasting blood glucose, and retinal barrier permeability of rats in each group were detected. The levels of malondialdehyde (MDA) and superoxide dismutase (SOD) in rat serum were measured using kits. Terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-biotin nick end labeling (TUNEL) assay was performed to determine the apoptosis of optic ganglion cells in rat retinal tissues. Additionally, the messenger RNA (mRNA) and protein levels of Ndrg2, IL-6 and STAT3 in rat retinal tissues were detected via reverse transcription-polymerase chain reaction (RT-PCR) and Western blotting, respectively. Compared with Control group, Model group had reduced body weight of rats, increased blood glucose and retinal permeability of rats, raised serum MDA content, decreased SOD activity, up-regulated apoptotic rate of optic ganglia, and notably elevated mRNA and protein levels of Ndrg2, IL-6 and STAT3 in retinal tissues. Compared with those in Model group, the body weight of rats declined, the blood glucose of rats rose, the retinal permeability of rats was decreased significantly, the serum MDA content was reduced, the SOD activity was raised, the apoptotic rate of optic ganglia was decreased, and the mRNA and protein levels of Ndrg2, IL-6 and STAT3 in retinal tissues were also decreased significantly in miR-375 siRNA group. MiR-375 inhibitors are able to reduce blood glucose, retinal permeability, and optic ganglion apoptosis in rats with DR, and the mechanism of action may be related to the regulation on the Ndrg2/IL-6/STAT3 signaling pathway.

Comparison of Structural Defects between Optic Disc and Ganglion Cell Complex in Patients with Glaucoma

Purpose: To evaluate the agreement of glaucomatous structural defects of the ganglion cell complex (GCC) detected with the spectral domain optical coherence tomography (sdOCT) with the optic nerve head alterations detected with the Heidelberg retina tomography (HRT), of glaucoma patients with ocular hypertension or open angle glaucoma.
 Material and Methods: Ninety patients eyes with structural glaucomatous defects were enrolled. All of them underwent imaging examination of GCC with sdOCT and the optic disk with HRT. The Cohen's kappa coefficient of agreement was used.
 Results: The agreement between the optic disc and GCC using the parameters of the programs analysis of the HRT, the moorfields regression analysis (MRA) and glaucoma probability score (GPS) was not significant. Instead between MRA and GPS a good agreement was calculated. Significant agreements were found between MRA and GPS on one hand and GCC on the other, considering location and length of the glaucomatous damage, while non significant agreements were found between GPS and GCC for the location and the length of the glaucomatous structural defect.
 Conclusions: There is no significance (Please explain further if you are referring to significance in terms of the difference, similarity or agreement) between HRT and sdOCT for the detection of the glaucomatous damage between the optic nerve head and the ganglion cell complex. Instead MRA and GCC detect comparable areas and lengths of the glaucomatous damage. On the other hand GPS records larger deficits relative to MRA and has not a significant agreement with the study of GCC.

Visual function restoring after trabeculectomy: between dream and reality

Glaucoma is characterized by the progressive degeneration of the optic nerve head (ONH) and retinal ganglion cells (RGCs). RGCs can be divided into basic regions, including the axon and synapse, the dendritic arbor, and the cell body (1). These compartments can independently be affected by degeneration processes and cause damage of the ONH (1,2).

GABA-, histamine-, and FMRFamide-immunoreactivity in the visual, vestibular and central nervous systems of Hermissenda crassicornis.

Hermissenda crassicornis is a model for studying the molecular and cellular basis for classical conditioning, based on its ability to associate light with vestibular stimulation. We used confocal microscopy to map histamine (HA), FMRF-amide, and γ-aminobutyric acid (GABA) immunoreactivity in the central nervous system (CNS), eyes, optic ganglia and statocysts of the nudibranchs. For HA immunoreactivity, we documented both consistently and variably labeled CNS structures across individuals. We also noted minor differences in GABA immunoreactivity in the CNS compared to previous work on Hermissenda. Contrary to expectations, we found no evidence for GABA inside the visual or vestibular systems. Instead, we found only FMRFamide- and HA immunoreactivity (FMRFamide: 4 optic ganglion cells, 4-5 hair cells; HA: 3 optic ganglion cells, 8 hair cells). Overall, our results can act as basis for comparisons of nervous systems across nudibranchs, and suggest further exploration of intraspecific plasticity versus evolutionary changes in gastropod nervous systems.

Heterozygous Pitx2 Null Mice Accurately Recapitulate the Ocular Features of Axenfeld-Rieger Syndrome and Congenital Glaucoma.

PurposeThe purpose of this analysis was to assess the utility of Pitx2+/− mice as a model for the ocular features of Axenfeld-Rieger Syndrome and for congenital glaucoma.MethodsEyes of Pitx2+/− and wild-type littermates were examined clinically using optical coherence tomography (OCT) and fundus photography. Intraocular pressures were measured using a TonoLab rebound tonometer. Eyes were examined histologically to assess PITX2 expression, structural integrity, and optic nerve and ganglion cell content.ResultsPITX2 is present postnatally in the corneal endothelium and stroma, iris stroma, trabecular meshwork, and Schlemm's canal. Reduced central corneal thickness, iris defects, and iridicorneal adhesions are all prevalent in Pitx2+/− eyes. Although optic nerve heads appear normal at postnatal day 7, IOP is elevated and optic nerve head cupping is fully penetrant in Pitx2+/− eyes by 3 weeks of age. Neurodegeneration is present in a significant percentage of optic nerves from Pitx2+/− mice by 3 weeks of age, and is fully penetrant by 2 months of age. Pitx2+/− eyes show significant reductions in specifically ganglion cell density in all four quadrants by 2 months of age.ConclusionsPitx2+/− mice model the major ocular features of Axenfeld-Rieger Syndrome and will be an important resource for understanding the molecular mechanisms leading to anterior segment dysgenesis and a high prevalence of glaucoma in this disease. In addition, these mice may provide an efficient new model for assessing the molecular events in glaucoma more generally, and for developing and testing new treatment paradigms for this disease.

Avoiding Clinical Misinterpretation and Artifacts of Optical Coherence Tomography Analysis of the Optic Nerve, Retinal Nerve Fiber Layer, and Ganglion Cell Layer.

Background:Optical coherence tomography (OCT) has become an important tool for diagnosing optic nerve disease. The structural details and reproducibility of OCT continues to improve with further advances in technology. However, artifacts and misinterpretation of OCT can lead to clinical misdiagnosis of diseases if they go unrecognized.Evidence Acquisition:A literature review using PubMed combined with clinical and research experience.Results:We describe the most common artifacts and errors in interpretation seen on OCT in both optic nerve and ganglion cell analyses. We provide examples of the artifacts, discuss the causes, and provide methods of detecting them. In addition, we discuss a systematic approach to OCT analysis to facilitate the recognition of artifacts and to avoid clinical misinterpretation.Conclusions:While OCT is invaluable in diagnosing optic nerve disease, we need to be cognizant of the artifacts that can occur with OCT. Failure to recognize some of these artifacts can lead to misdiagnoses and inappropriate investigations.

Caspase-7: a critical mediator of optic nerve injury-induced retinal ganglion cell death.

BackgroundAxonal injury of the optic nerve (ON) is involved in various ocular diseases, such as glaucoma and traumatic optic neuropathy, which leads to apoptotic death of retinal ganglion cells (RGCs) and loss of vision. Caspases have been implicated in RGC pathogenesis. However, the role of caspase-7, a functionally unique caspase, in ON injury and RGC apoptosis has not been reported previously. The purpose of this study is to evaluate the role of caspase-7 in ON injury-induced RGC apoptosis.ResultsC57BL/6 (wildtype, WT) and caspase-7 knockout (Casp7−/−) mice were used. We show that ON crush activated caspase-7 and calpain-1, an upstream activator of caspase-7, in mouse RGCs, as well as hydrolysis of kinectin and co-chaperone P23, specific substrates of caspase-7. ON crush caused a progressive loss of RGCs to 28 days after injury. Knockout of caspase-7 partially and significantly protected against the ON injury-induced RGC loss; RGC density at 28 days post ON crush in Casp7−/− mice was approximately twice of that in WT ON injured retinas. Consistent with changes in RGC counts, spectral-domain optical coherence tomography analysis revealed that ON crush significantly reduced the in vivo thickness of the ganglion cell complex layer (including ganglion cell layer, nerve fiber layer, and inner plexiform layer) in the retina. The ON crush-induced thinning of retinal layer was significantly ameliorated in Casp7−/− mice when compared to WT mice. Moreover, electroretinography analysis demonstrated a decline in the positive component of scotopic threshold response amplitude in ON crushed eyes of the WT mice, whereas this RGC functional response was significantly higher in Casp7−/− mice at 28 days post injury.ConclusionAltogether, our findings indicate that caspase-7 plays a critical role in ON injury-induced RGC death, and inhibition of caspase-7 activity may be a novel therapeutic strategy for glaucoma and other neurodegenerative diseases of the retina.Electronic supplementary materialThe online version of this article (doi:10.1186/s13024-015-0039-2) contains supplementary material, which is available to authorized users.

Effects of phenolic acid metabolites formed after chlorogenic acid consumption on retinal degeneration in vivo.

Although ingestion of coffee and its constituent chlorogenic acid (CGA) protects the retina from oxidative stress, the bioaccessibility and bioavailability of coffee metabolites are not well understood. The aim of this study was to determine which coffee metabolites reach the retina and protect against retinal degeneration. UPLC-MS/MS was used to detect CGA and coffee metabolites in the rat eye. The methyl thiazolyl tetrazolium assay and double staining with Hoechst and propidium iodide showed that CGA, caffeic acid (CA), and dihydrocaffeic acid (DHCA) protect retinal ganglion cells from hypoxia-induced damage. Western blots showed that treatment with coffee metabolites up-regulated anti-apoptotic proteins such as Bcl-2 and Bcl-XL and down-regulated pro-apoptotic proteins such as Bad, PARP, and cleaved caspase 3. Adult ICR mice were subjected to optic nerve crush-induced retinal ganglion cell death with intravitreal pre-treatment with coffee metabolites 1 day before and 1 h after the procedure. Retrograde Fluorogold(TM) labeling showed severe retinal ganglion cell loss after optic nerve crushing, and coffee metabolites significantly reduced damage to retinal ganglion cells. CGA and coffee metabolites, especially, CA, and DHCA, reach the eye, where they can significantly reduce apoptosis induced by hypoxia and optic nerve crush stress, and thus prevent retinal degeneration.