Oxygen and Glucose Deprivation on Human Müller Cells (MIO-M1) and Human Organotypic Retinal Cultures (HORCs) in Relation to Glaucoma

Purpose: The purpose of this research was to investigate the effect of glaucoma-related insults, specifically oxygen and/or glucose deprivation (OGD) on the survival and genes expression of human Müller cells (MIO-M1), and retinal ganglion cells (RGCs) using the human organotypic retinal culture (HORC) model. Methods: MIO-M1 cells and HORCs were exposed to different levels of OGD using a custom-built chamber to control oxygen levels. Cell survival was evaluated using MTS and LDH assays while RGC death in HORCs was investigated using NeuN immunohistochemistry and TUNEL-labelling. Expression of genes of interest was assessed using QRT-PCR. Results: Reduced levels of oxygen and glucose (1.11mMglucose/4%O2) caused proliferation of MIO-M1 cells. Full deprivation of glucose caused cell death, but full hypoxia did not affect survival. In HORCs, glucose deprivation and OGD, but not oxygen deprivation alone, caused loss of RGCs. Different levels of OGD regulated expression of genes associated with angiogenesis, glial activation, excitotoxicity and neuroprotection in MIO-M1 cells and HORCs. VEGF expression significantly increased in MIO-M1 cells and HORCs treated with full OGD, and VEGF protein was secreted under reduced levels (1.11mMglucose/4%O2). Secretion of VEGF in MIO-M1 cells and HORCs was also increased under conditions of raised glucose. The PKCβ inhibitor LY333531 decreased VEGF secretion under conditions of raised glucose and hypoxia. Co-culture of MIO-M1 cells resulted in more damage/apoptosis to HORCs and reduced RGCs survival. Conclusions: Use MIO-M1 cells and the HORC model were effective in studying the effect of OGD in relation to glaucoma. Glucose rather than oxygen was the key survival factor for RGCs and MIO-M1 cells. The secreted factors by Müller cells could have protective and detrimental effects on RGC survival. Investigation of mechanisms using these models may be of benefit in development of potential therapeutic interventions for retinal neurodegenerative diseases including glaucoma

Visual resolution under photopic and mesopic conditions in patients with Sjögren's syndrome

AIM: To focus on different visual resolution tasks under photopic and mesopic conditions in Sjögren's syndrome patients compared to age-matched healthy controls. METHODS: The visual resolution measurements included high and low visual acuities and contrast sensitivity functions. These tests were conducted under photopic and then mesopic conditions. Twenty-one Sjögren's syndrome patients and 21 aged-matched healthy volunteers completed all the measurements in this study. RESULTS: Sjögren's syndrome patients have greater impairment in contrast sensitivity than standardized visual acuity. This reduction was significant under the mesopic condition. Also, Sjögren's syndrome patients treated with pilocarpine suffer more than patients without pilocarpine treatment under low light conditions. CONCLUSION: Sjögren's syndrome patients shows greater impairment in different visual resolution tasks due to dry eye symptoms

Hydrostatic pressure does not cause detectable changes to survival of human retinal ganglion

Purpose: Elevated intraocular pressure (IOP) is a major risk factor for glaucoma. One consequence of raised IOP is that ocular tissues are subjected to increased hydrostatic pressure (HP). The effect of raised HP on stress pathway signaling and retinal ganglion cell (RGC) survival in the human retina was investigated. Methods: A chamber was designed to expose cells to increased HP (constant and fluctuating). Accurate pressure control (10-100mmHg) was achieved using mass flow controllers. Human organotypic retinal cultures (HORCs) from donor eyes (<24h post mortem) were cultured in serum-free DMEM/HamF12. Increased HP was compared to simulated ischemia (oxygen glucose deprivation, OGD). Cell death and apoptosis were measured by LDH and TUNEL assays, RGC marker expression by qRT-PCR (THY-1) and RGC number by immunohistochemistry (NeuN). Activated p38 and JNK were detected by Western blot. Results: Exposure of HORCs to constant (60mmHg) or fluctuating (10-100mmHg; 1 cycle/min) pressure for 24 or 48h caused no loss of structural integrity, LDH release, decrease in RGC marker expression (THY-1) or loss of RGCs compared with controls. In addition, there was no increase in TUNEL-positive NeuN-labelled cells at either time-point indicating no increase in apoptosis of RGCs. OGD increased apoptosis, reduced RGC marker expression and RGC number and caused elevated LDH release at 24h. p38 and JNK phosphorylation remained unchanged in HORCs exposed to fluctuating pressure (10-100mmHg; 1 cycle/min) for 15, 30, 60 and 90min durations, whereas OGD (3h) increased activation of p38 and JNK, remaining elevated for 90min post-OGD. Conclusions: Directly applied HP had no detectable impact on RGC survival and stress-signalling in HORCs. Simulated ischemia, however, activated stress pathways and caused RGC death. These results show that direct HP does not cause degeneration of RGCs in the ex vivo human retina

Correlation between dry eye and refractive error in Saudi young adults using noninvasive Keratograph 4

Purpose: The purpose is to study the correlation between dry eye and refractive errors in young adults using noninvasive Keratograph. Methods: In this cross sectional study, a total of 126 participants in the age range of 19–25 years and who were free of ocular surface disease, were recruited from King Saud University Campus. Refraction was defined by the spherical equivalent (SE) as the following: 49 emmetropic eyes (±0.50 SE), 48 myopic eyes (≤−0.75 SE and above), and 31 hyperopic eyes (>+0.75 SE). All participants underwent full ophthalmic examinations assessing their refractive status and dryness level including noninvasive breakup time (NIBUT) and tear meniscus height using Keratograph 4. Results: The prevalence of dry eye was 24.6%, 36.5%, and 17.4% in emmetropes, myopes, and hypermetropes, respectively. NIBUT has a negative correlation with hyperopia and a positive correlation with myopia with a significant reduction in the average NIBUT in myopes and hypermetropes in comparison to emmetropes. Conclusion: The current results succeeded to demonstrate a correlation between refractive errors and dryness level

Knowledge of Saudi Patients with Autoimmune Diseases about Hydroxychloroquine Toxicity: The Role of Physician&ndash;Patient Communication

This cross-sectional internet-based questionnaire aimed to assess the knowledge and experience of autoimmune disease patients in Saudi Arabia of the ocular effects of hydroxychloroquine (HCQ). Among the 245 respondents, discontinuation of the drug was linked to its ocular toxicity in approximately 7.3%. Most patients had taken HCQ for a period longer than five years, exceeding a dose of 5 mg/Kg. A lack of education and physician communication about medication toxicity was reported by approximately 40.8% of the participants. Despite the knowledge about HCQ retinopathy, the drug is prescribed to autoimmune disease patients at an inappropriate dosage. Knowledge obtained from physicians&rsquo; communication may improve the health outcomes of chronically ill patients. Rheumatologists and ophthalmologists should work together to recognize patients at risk of hydroxychloroquine toxicity and ensure they receive proper education and adhere to periodic follow-up

Self-Efficacy of Saudi Patients with Autoimmune Diseases in Managing Hydroxychloroquine-Induced Ocular Complications: A Cross-Sectional Survey

Rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE) are common autoimmune diseases (AD) that affect joints and have multi-organ involvement that results in disability, morbidity, and increased mortality. Both conditions are known to cause a wide range of ocular manifestations. Antimalarial drugs, mainly hydroxychloroquine (HCQ), are among the treatment options for AD that is uniquely characterized by retinopathy as a main side effect. This study examines self-efficacy levels in autoimmune disease patients who were or are currently treated with HCQ and related factors such as patient education, communication with the physician, self-education, and ability to cope with the disease

Effect of Muslim Prayer (Salat) positions on the intra-ocular pressure in healthy young individuals

Purpose: There is a lack of research examining the effects of Muslim prayer (Salat) positions on the intra-ocular pressure (IOP). Considering its involvement with postural changes, this study aimed to investigate the changes in the IOP upon assuming Salat positions before, immediately after, and after 2 minutes of prayer in healthy young adults. Methods: This prospective, observational study recruited healthy young individuals aged between 18 and 30 years. The IOP measurements were obtained in one eye using Auto Kerato-Refracto-Tonometer TRK-1P, Topcon at baseline before assuming prayer positions, immediately after, and after 2 minutes of the prayer. Results: Forty female participants were recruited, with a mean age of 21 ± 2.9 years, a mean weight of 59.7 ± 14.8 (kg), and a mean body mass index (BMI) of 23.8 ± 5.7 (kg/m2). Only 16% had a BMI ≥25 kg/m2 (n = 15). All participants started with a mean IOP at baseline of 19.35 ± 1.65 mmHg, which increased to 20 ± 2.38 mmHg and declined to 19.85 ± 2.67 mmHg after 2 minutes of Salat. The difference between the mean IOPs at baseline, immediately after, and after 2 minutes of Salat was not significant (p = 0.06). However, there was a significant difference between the baseline IOP measurements and those immediately after Salat (p = 0.02). Conclusion: A significant difference was found between the IOP measurements at baseline and immediately after Salat; however, this was not clinically significant. Further investigation is warranted to confirm these findings and explore the effect of a longer duration of Salat in glaucoma and glaucoma suspect patients

The system used to expose retinal tissue to raised hydrostatic pressure.

<p>(A) Schematic diagram of the hydrostatic pressure system (not to scale). Examples of computer controlled protocols using the pressure system at (B) constant (60mmHg) pressure for 24h and (C) fluctuating (10–100mmHg; 1 cycle/min) pressure for 1h. MFC = mass flow controller.</p

Elevated pressure did not activate p38 or JNK stress signalling pathways.

<p>Phosphorylation of (A) p38 and (B) JNK, relative to their total expression, did not significantly alter with fluctuating pressure in HORCs (n = 3; 15 min- p38 p = 0.769, JNK p = 0.354; 30 min—p38 p = 0.696, JNK p = 0.667; 60 min—p38 p = 0.232, JNK p = 0.891; 90min-p38 p = 0.273, JNK p = 0.833). Phosphorylation of (C) p38 and (D) JNK was observed immediately following 3h OGD (n = 3; 0 min—p38 p = 0.012, JNK p = 0.006), and in the during the following reperfusion period in control medium (n = 3; 60 min—p38 p = 0.019, JNK p = 0.039; 90 min—JNK p = 0.049). Results are expressed as a percentage of the untreated control. Representative blots are shown.</p

Elevated hydrostatic pressure did not decrease the expression of RGC specific markers in HORCs or cause RGC apoptosis.

<p>(A) Constant (HP(C); 60mmHg) or fluctuating (HP(F) 10–100mmHg; 1cycle/min) pressure did not decrease the number of NeuN-labelled RGCs at the 24 or 48h time-points (HP(C) 60mmHg 24h—n = 9, p = 0.947; HP(C) 60mmHg 48h—n = 9, p = 0.668; HP(F) 10–100mmHg 24h—n = 10, p = 0.955; (HP(F) 10–100mmHg 48h—n = 10; p = 0.733). A significant reduction in NeuN-labelled cells was observed following simulated ischemia (3h OGD/21h control conditions) (n = 9; *p = 0.002). (B) Elevated HP for 24 or 48h did not reduce <i>THY-1</i> mRNA expression compared to same time point controls (HP(C) 60mmHg 24h—n = 4, p = 0.878; HP(C) 60mmHg 48h—n = 4, p = 0.837; HP(F) 10–100mmHg 24h—n = 4, p = 0.584; HP(F) 10–100mmHg—n = 4; p = 0.516). A significant reduction in <i>THY-1</i> expression was caused by 3h OGD/21h control conditions (n = 8; *p = 0.010). (C-G) Apoptotic labelling in RGCs was low with no increase in the number of TUNEL+ NeuN-labelled cells at 24 or 48h after constant or fluctuating pressure compared to controls (HP(C) 60mmHg 24h—n = 4, p = 0.531; HP(C) 60mmHg 48h—n = 4, p = 0.349; HP(F) 10–100mmHg 24h—n = 4, p = 0.695; HP(F) 10–100mmHg—n = 4; p = 0.853). An increase in the proportion of apoptotic RGCs could be detected following 3h OGD/ 21h control conditions (n = 4; *p = 0.011). DAPI = blue, TUNEL = red, NeuN = green, GCL = ganglion cell layer. White arrows highlight TUNEL+ NeuN-labelled cells. Scale = 200μm.</p