Circadian rhythm of intraocular pressure.

Intraocular pressure (IOP) plays a crucial role in glaucoma development, involving the dynamics of aqueous humor (AH). AH flows in from the ciliary body and exits through the trabecular meshwork (TM). IOP follows a circadian rhythm synchronized with the suprachiasmatic nucleus (SCN), the circadian pacemaker. The SCN resets peripheral clocks through sympathetic nerves or adrenal glucocorticoids (GCs). IOP's circadian rhythm is governed by circadian time signals, sympathetic noradrenaline (NE), and GCs, rather than the local clock. The activity of Na+/K+-ATPase in non-pigmented epithelial cells in the ciliary body can influence the nocturnal increase in IOP by enhancing AH inflow. Conversely, NE, not GCs, can regulate the IOP rhythm by suppressing TM macrophage phagocytosis and AH outflow. The activation of the ß1-adrenergic receptor (AR)-mediated EPAC-SHIP1 signal through the ablation of phosphatidylinositol triphosphate may govern phagocytic cup formation. These findings could offer insights for better glaucoma management, such as chronotherapy.

Effect of digital ocular massage on intraocular pressure and Schlemm's canal dimensions.

Digital ocular massage has been reported to temporarily lower intraocular pressure (IOP). This could be related to an enhanced aqueous humor outflow; however, the mechanism is not clearly understood. Using anterior segment optical coherence tomography, the Schlemm's canal (SC) and trabecular meshwork (TM) can be imaged and measured. Here, 66 healthy adults underwent digital ocular massage for 10 min in their right eyes. The IOP and dimensions of the SC and TM were measured before and after ocular massage. All subjects demonstrated IOP reduction from 15.7 ± 2.5 mmHg at baseline to 9.6 ± 2.2 mmHg immediately after, and median of 11.6 mmHg 5-min after ocular massage (Friedman's test, p < 0.001). There was significant change in SC area (median 10,063.5 µm2 at baseline to median 10,151.0 µm2 after ocular massage, Wilcoxon test, p = 0.02), and TM thickness (median 149.8 µm at baseline to 144.6 ± 25.3 µm after ocular massage, Wilcoxon test, p = 0.036). One-third of the subjects demonstrated collapse of the SC area (-2 to -52%), while two-thirds showed expansion of the SC area (2 to 168%). There were no significant changes in SC diameter (270.4 ± 84.1 µm vs. 276.5 ± 68.7 µm, paired t-test, p = 0.499), and TM width (733.3 ± 110.1 µm vs. 733.5 ± 111.6 µm, paired t-test, p = 0.988). Eyes with a higher baseline IOP demonstrated a greater IOP reduction (Pearson correlation coefficient r = -0.521, p < 0.001). Eyes with smaller SC area at baseline showed greater SC area expansion (Pearson correlation coefficient = -0.389, p < 0.001). Greater IOP reduction appeared in eyes with greater SC area expansion (Pearson correlation coefficient r = -0.306, p = 0.01). Association between change in IOP and change in TM thickness was not significant (Spearman's ρ = 0.015, p = 0.902). Simple digital ocular massage is an effective method to lower IOP values, and change in the SC area was significantly associated with IOP changes.

Detection of aqueous humor cytokines in diabetic retinopathy and its clinical significance / 中华实验眼科杂志

Objective:To detect the concentration of various cytokines in aqueous humor of patients with diabetes retinopathy (DR) with Luminex liquid chip, and analyze the relationship between the cytokines and the occurrence and development of DR.Methods:A cross-sectional study was conducted.Sixty-three DR patients (97 eyes) treated with anti-vascular endothelial growth factor (VEGF) drugs in the First Affiliated Hospital of Guangzhou University of Traditional Chinese Medicine from March 1, 2019 to December 31, 2019 were enrolled as DR group, including 38 nonproliferative DR (NPDR) eyes in NPDR group and 59 proliferative DR (PDR) eyes in PDR group, 39 eyes in photocoagulation group and 58 eyes in non-photocoagulation group.Twenty-seven patients (31 eyes) hospitalized for cataract surgery at the same time were collected as the control group.Aqueous humor was extracted during the operation, and Luminex liquid chip was used to detect the concentrations of vascular endothelial growth factor-A (VEGF-A), placental growth factor (PLGF), platelet-derived growth factor (PDGF)-AA, PDGF-BB, angiopoietin-like protein 4 (ANGPTL4), interleukin-6 (IL-6), IL-8, IL-1β, monocyte chemotactic protein-1 (MCP-1), intercellular cell adhesion molecule-1 (ICAM-1) and tumor necrosis factor-α (TNF-α) in aqueous humor.The concentrations of various cytokines of different groups were compared, and the correlation among various aqueous humor cytokines was analyzed by Spearman rank correlation analysis.This study adhered to the Declaration of Helsinki.The study protocol was approved by the Ethics Committee of First Affiliated Hospital of Guangzhou University of Chinese Medicine (No.Y[2019]230). Written informed consent was obtained from each patient.Results:The concentrations of VEGF-A, PLGF, PDGF-AA, ANGPTL4, IL-6, IL-8, MCP-1 and ICAM-1 in DR group were significantly higher and the concentration of IL-1β was significantly lower than those of control group ( Z=-4.747, -5.164, -3.373, -8.062, -4.535, -5.954, -5.098, -3.228, -5.954, all at P<0.01). The concentrations of VEGF-A, PLGF, PDGF-AA, ANGPTL4, IL-6, IL-8 and MCP-1 of the photocoagulation and non-photocoagulation groups were higher and the concentration of IL-1β was significantly lower than those in the control group (all at P<0.017). The concentration of ICAM-1 in the photocoagulation group was significantly higher than that in the control group ( P<0.017). The concentrations of PLGF, PDGF-AA and ANGPTL4 of PDR group were higher than those of NPDR group, and the differences were statistically significant ( Z=-2.291, -3.396, -2.276, all at P<0.05). VEGF-A was positively correlated with the other cytokines except ICAM-1 ( rs=0.237-0.540, all at P<0.05). ANGPTL4 was positively correlated with the other cytokines except IL-1β ( rs=0.361-0.733, all at P<0.01). Conclusions:The occurrence and development of DR are closely related to VEGF family, PDGF family, ANGPTL family and inflammatory factors.The concentrations of PLGF, PDGF-AA and ANGPTL4 are higher in PDR eyes.There are close and complex relationships among a variety of cytokines in the eyes of DR patients.

Changes in Aqueous Humor Lutein Levels of Patients with Cataracts after a 6-Week Course of Lutein-Containing Antioxidant Supplementation.

PURPOSE: Oxidative damage is known to be an important cause of age-related cataracts and it has been suggested that administration of antioxidants, such as lutein, may delay the onset and progression of cataracts. Our previous investigation of human aqueous humor after the intake of a lutein-containing supplement demonstrated decreases in peroxidative products. This study evaluated the transportation of lutein into aqueous humor which is an important factor when measuring the antioxidant effects of lutein on the lens. METHODS: This study enrolled 155 patients with binocular cataracts of the same grade. Serum and aqueous humor samples were collected during cataract surgery before (as pre-intake samples) and after 6 weeks of oral intake of Ocuvite + Lutein® (as post-intake samples). Lutein levels were measured with high-performance liquid chromatography. RESULTS: Lutein levels in both the serum and aqueous humor were significantly higher in the post-intake than the pre-intake samples. There were significant increases in the lutein levels in patients with lower pre-intake lutein serum levels. There was also a tendency for greater increases in patients with lower pre-intake aqueous humor lutein levels. CONCLUSIONS: These results demonstrate that oral lutein supplementation increases lutein levels, which further induce decreases in peroxidation in the aqueous humor. Furthermore, lutein supplementation may be more effective in patients with lower serum lutein levels.

Hemodialysis Effect on the Composition of the Eye Fluid of Cataract Patients.

Numerous reports have proven that dialysis patients experience disturbances in the levels of elements in biological fluids. Disturbances in the homeostasis of essential elements or the appearance of highly toxic elements are serious problems also in clinical ophthalmology. The purpose of this study was to investigate the influence of hemodialysis (HD) on the elemental composition of anterior chamber aqueous humor (AH) in patients undergoing cataract surgery. The study involved 22 patients. The control group enrolled 16 patients (age 75.68 ± 9.67, female 54.55%, male 45.45%) with cataract and normal kidney function (control), and the second group included six patients (age 70.33 ± 12.74, female 33.33%, male 66.67%) with cataract undergoing HD treatment. The elements quantification was established using an inductively coupled plasma optical emission spectrometer (ICP-MS). In the eye fluid of dialysis patients, there were increased levels of manganese (Mn) and mercury (Hg) and decreased levels of vanadium (V) and zinc (Zn). In addition, a statistically significant increase in the Hg/Zn and Hg/selenium (Se) ratios and a lowering of the iron (Fe)/Mn ratio were observed in the studied group in comparison to the control. The obtained results indicated the need for Zn and Se supplementation in order to eliminate the hazards caused by Hg toxicity. A lower level of V in the eye fluid of dialysis patients may have a positive effect on maintaining a calcium and phosphorus homeostasis. Our study gives a deep insight into changes of elements concentrations in AH induced by HD.

Ascorbic acid concentrations in aqueous humor after systemic vitamin C supplementation in patients with cataract: pilot study.

BACKGROUND: To measure ascorbic acid concentration in aqueous humor of patients with cataract after oral or intravenous vitamin C supplementation. METHODS: Forty-two eyes of 42 patients with senile cataract who underwent uncomplicated cataract surgery were enrolled. Patients (n = 14 each) were administered oral vitamin C (2 g), intravenous vitamin C (20 g) or no treatment (control group) on the day before surgery. Samples of aqueous humor (0.1 cm3) were obtained by anterior chamber aspiration at the beginning of surgery and stored at -80 °C. Ascorbic acid concentration in aqueous humor was measured by high-pressure liquid chromatography. RESULTS: The mean age at surgery was 62.5 years, with no difference among the three groups. The mean ± standard deviation concentrations of ascorbic acid in aqueous humor in the control and oral and intravenous vitamin C groups were 1347 ± 331 µmol/L, 1859 ± 408 µmol/L and 2387 ± 445 µmol/L, respectively. Ascorbic acid concentration was significantly lower in the control than in the oral (P < 0.01) and intravenous (P < 0.001) vitamin C groups and was significantly higher in the intravenous than in the oral vitamin C group (P < 0.05). CONCLUSIONS: Ascorbic acid concentration in aqueous humor is increased by systemic vitamin C supplementation, with intravenous administration being more effective than oral administration.

Simultaneous determination of seven alkaloids from Rhizoma Corydalis Decumbentis in rabbit aqueous humor by LC-MS/MS: Application to ocular pharmacokinetic studies.

This study aims to establish a fast and sensitive LC-MS/MS method for simultaneous determination of seven alkaloids from Rhizoma Corydalis Decumbentis in rabbit aqueous humor. Aqueous humor samples were processed by protein precipitation and then separated on a Thermo Syncronis C18 column (50mm×2.1mm, 5µm) with a mobile phase using acetonitrile-0.05% formic acid (28:72, v/v). Detection of the analytes and the internal standard (coptisine) were performed in positive electrospray ionization with selected reaction monitoring. The method showed good linearity (r>0.9931) for all the seven alkaloids. This fully validated method was applied to the studies of aqueous humor pharmacokinetics of seven alkaloids from Rhizoma Corydalis Decumbentis and the effects of borneol on corneal penetration of these alkaloids into aqueous humor. This is the first work that presents a reliable LC-MS/MS method for simultaneous determination of seven alkaloids in rabbit aqueous humor and its application of ocular pharmacokinetics of seven alkaloids from Rhizoma Corydalis Decumbentis.

Fluctuation of lysosomal phospholipase A2 in experimental autoimmune uveitis in rats.

Intraocular inflammation leads to oxidative stress and may generate lipid oxidation products. The present study was conducted to elucidate the pathophysiological roles of the lysosomal phospholipase A2 (LPLA2), a phospholipid-degrading enzyme, and the production of oxidized phospholipids (oxPLs) in autoimmune uveitis using a rat model. Lewis rats were immunized with a bovine interphotoreceptor retinoid-binding protein (bIRBP) peptide with complete Freund's adjuvant (CFA) to induce experimental autoimmune uveitis (EAU). The aqueous humor (AH) and serum were collected every week for 4 weeks from the immunized rats. The LPLA2 activity of the AH and serum was detected using liposomes consisting of 1,2-dioleoylphosphatidylglycerol/N-acetylsphingosine as the substrate under acidic conditions. Immunohistochemical analysis was performed using antibodies against LPLA2 and oxPLs. The ocular inflammation was exacerbated at 2 weeks after immunization. The LPLA2 activity in the rat AH was increased by EAU induction, and was concomitant with the extent of inflammation in the anterior chamber (AC). In contrast, the LPLA2 activity in the rat serum was not influenced by EAU induction. At 2 weeks after immunization, immunoreactivity of LPLA2 was observed in infiltrated macrophages in the AC and vitreous cavity of the EAU rats. Furthermore, immunoreactivity of oxPLs was observed in the infiltrated macrophages of EAU rat eyes. These results demonstrated that the LPLA2 activity of the AH is augmented with the inflammation in the AC. The high expression of LPLA2 and production of oxPLs are found in the infiltrated macrophages in the acute inflammation of EAU rats. The present findings suggest the connection between LPLA2 activity and oxPL metabolism in the inflammation sites in the eye.

Lymphatic drainage from the eye: A new target for therapy.

Lowering intraocular pressure (IOP) has been central to glaucoma care for over a century. In order to prevent sight loss from disease, there has been considerable focus on medical and surgical methods to improve fluid drainage from the eye. In spite of this, our understanding of exactly how aqueous humor leaves the eye is not complete. Recently, lymphatic vessels have been discovered in the human uvea, with studies showing lymphatic fluid outflow in several models, in addition to evidence for their pharmacological enhancement. The presence of a lymphatic outflow system points to an exciting, expanded understanding of how fluid and particulate materials such as proteins move out of the eye, and how IOP may be regulated. We coin the term "uveolymphatic pathway"-to reflect a comprehensive and compelling new target for glaucoma and an exciting opportunity for future investigations to better understand the eye in health and disease.

The gender-differentiated antioxidant effects of a lutein-containing supplement in the aqueous humor of patients with senile cataracts.

Antioxidant supplements are expected to decrease oxidative damage and prevent ocular diseases. In this study, changes in the anti-oxidative ability and oxidative status in the aqueous humor before and after intake of a lutein-containing supplement were measured. Forty patients who all had identical grades of cataracts in both eyes were included. The aqueous humor was collected as pre-intake samples during cataract surgery. Ocuvite + Lutein(Ⓡ), an antioxidant supplement, was administered orally beginning the day after surgery. Six weeks later, the aqueous humor was collected as a post-intake sample during cataract surgery of the opposite eye. To determine the anti-oxidative ability, the levels of superoxide (O2(*-)) scavenging activity were measured. To determine the oxidative status, the levels of hydrogen peroxide (H2O2) and total amount of hydroperoxides (TH, including H2O2 and peroxides of lipids, proteins, and nucleic acids) were measured. In post-intake samples, the O2(*-) scavenging activities were significantly higher in both genders (p < 0.05). The levels of H2O2 were significantly higher (p < 0.01) while the levels of TH were significantly lower (p < 0.01) only in females. The level of H2O2 was significantly negatively correlated to the TH in the post-intake samples of both genders (r = -0.50 and p < 0.05 for males; r = -0.59 and p < 0.01 for females) while the level of H2O2 was significantly positively correlated to the O2(*-) scavenging activity in both pre- and post-intake aqueous humor in females only (r = 0.66 and p < 0.01 for pre-intake samples, r = 0.71 and p < 0.01 for post-intake samples). After the introduction of the antioxidant supplement, O2(*-) scavenging activity increased while H2O2 levels remained the same in males, suggesting that scavenging rates are proportional. In postmenopausal females, the superoxide scavenging activity also increased, however unlike in males, the H2O2 levels also increased meaning H2O2 was not completely scavenged. H2O2 is a non-free radical and can be excreted from the aqueous humor to prevent further oxidation of lipids, proteins, and nucleic acids, which was confirmed by the low levels of TH in post-intake samples. Antioxidant supplements are suggested to be effective in reducing oxidation in the aqueous humor by different mechanisms in both genders.

The influence of thalamosinusotomy under different constant intraocular pressures on aqueous outflow facility in isolated porcine eyes

OBJETIVO: Avaliar o efeito da thalamosinusotomia ab interno, que é um procedimento cirúrgico experimental similar a esclerotalamotomia ab interno, na drenagem do humor aquoso. MÉTODOS: Olhos de porco enucleados foram perfundidos com solução fisiológica de Krebs-Ringer e azul de tripan, sob diferentes pressões constantes de perfusão, após o procedimento cirúrgico experimental. A facilidade de drenagem e os tecidos corados/não corados foram medidos. RESULTADOS: A facilidade de drenagem e a área sob a curva (fluxo) aumentaram com o aumento do número de incisões da thalamosinusotomia (0 a 4). Olhos submetidos a thalamosinusotomia apresentaram mais tecido corado (conjuntiva, superfície externa e interna da esclera) que olhos submetidos a cirurgia sham, com diferença estatisticamente significativa (p< 0,05). CONCLUSÕES: Os resultados sugerem que a facilidade de drenagem aumenta com o aumento do número de thalamus, diferente vias de drenagem são estimuladas após a thalamosinusotomia, e a drenagem uveoscleral pode ser uma via importante após o procedimento cirúrgico experimental.

PURPOSE: To explorethe effect of the thalamosinusotomy ab interno, which is an experimental surgical procedure similar to sclerothalamotomy ab interno, on aqueous humor drainage. METHODS: Enucleated porcine eyes were perfused with Krebs-Ringer's physiologic solution and trypan blue, in vitro, under different constant pressures after the experimental procedure. The outflow facility and the stained/unstained tissue were measured. RESULTS: The outflow facility and the area under the curve (outflow) increased with the increasing number of thalamosinusotomy incisions (0 to 4). Thalamosinusotomy eyes showed more stained tissue (conjunctiva, outer sclera, inner sclera) than sham surgery eyes with significant statistical difference (P<0.05). CONCLUSIONS: The results suggested that outflow facility increases with the increasing number of thalamus, different pathways are stimulated after thalamosinusotomy, and the uveoscleral outflow could be an important route after the experimental surgical procedure.

Analysis of Aqueous Humor Calcium and Phosphate from Cataract Eyes with and without Diabetes Mellitus

PURPOSE: To compare the levels of calcium and phosphorus in the aqueous humor and serum of diabetics and non-diabetics. METHODS: We divided patients into two groups: seventy-six non-diabetic cataract patients and fifty-two diabetic cataract patients. The diabetic group was divided again into three subgroups: twenty-six patients with no diabetic retinopathy, thirteen patients with non-proliferative diabetic retinopathy, and thirteen patients with proliferative diabetic retinopathy. The authors compared the levels of calcium and phosphorus in the serum and aqueous humor of cataract patients. Statistic analysis was performed to form two comparisons: 1) a comparison between non-diabetics and diabetics and 2) a comparison among non-diabetics and the three subgroups of diabetics. RESULTS: In serum, calcium levels did not statistically differ between non-diabetics and diabetics. The phosphorus level was also not significantly different. In the aqueous humor, however, while calcium levels did not differ significantly, the phosphorus levels in diabetics were considerably higher than those in non-diabetics. When non-diabetics were compared to the three diabetic subgroups, calcium levels did not differ in serum or aqueous humor, but the phosphorus levels in diabetics with proliferative diabetic retinopathy were significantly higher than those in non-diabetics, diabetics without diabetic retinopathy, and diabetics with non-proliferative diabetic retinopathy. CONCLUSIONS: The level of phosphorus in the aqueous humor and serum of diabetics was significantly increased, especially in diabetics with proliferative diabetic retinopathy. This result may be related to hydrophilic acrylic IOL opacification. Future studies regarding the pathogenic role of a high concentration of aqueous humor and serum phosphorus are required.

Analysis of Aqueous Humor Calcium and Phosphate from Cataract Eyes with and without Diabetes Mellitus

PURPOSE: To compare the levels of calcium and phosphorus in the aqueous humor and serum of diabetics and non-diabetics. METHODS: We divided patients into two groups: seventy-six non-diabetic cataract patients and fifty-two diabetic cataract patients. The diabetic group was divided again into three subgroups: twenty-six patients with no diabetic retinopathy, thirteen patients with non-proliferative diabetic retinopathy, and thirteen patients with proliferative diabetic retinopathy. The authors compared the levels of calcium and phosphorus in the serum and aqueous humor of cataract patients. Statistic analysis was performed to form two comparisons: 1) a comparison between non-diabetics and diabetics and 2) a comparison among non-diabetics and the three subgroups of diabetics. RESULTS: In serum, calcium levels did not statistically differ between non-diabetics and diabetics. The phosphorus level was also not significantly different. In the aqueous humor, however, while calcium levels did not differ significantly, the phosphorus levels in diabetics were considerably higher than those in non-diabetics. When non-diabetics were compared to the three diabetic subgroups, calcium levels did not differ in serum or aqueous humor, but the phosphorus levels in diabetics with proliferative diabetic retinopathy were significantly higher than those in non-diabetics, diabetics without diabetic retinopathy, and diabetics with non-proliferative diabetic retinopathy. CONCLUSIONS: The level of phosphorus in the aqueous humor and serum of diabetics was significantly increased, especially in diabetics with proliferative diabetic retinopathy. This result may be related to hydrophilic acrylic IOL opacification. Future studies regarding the pathogenic role of a high concentration of aqueous humor and serum phosphorus are required.