Analysis of Plasma Hydrogen Sulfide, Homocysteine, and L-Cysteine in Open-Angle Glaucoma Patients.

Purpose: To compare the plasma levels of hydrogen sulfide (H2S), homocysteine (Hcy), and L-cysteine (Cys) among primary open-angle glaucoma (POAG), normal tension glaucoma (NTG), ocular hypertension (OHT), and normal individuals. To explore associated factors and evaluate their diagnostic abilities in glaucoma. Methods: POAG, NTG, OHT, and normal subjects were recruited from Ruijin Hospital between December 2016 and December 2018. All subjects underwent thorough ophthalmological examinations, and fasting venous blood was taken to determine the concentrations of H2S, Hcy, and Cys. Results: Forty-two POAG, 20 NTG, 52 OHT, and 78 controls were enrolled. The H2S levels in POAG group were significantly lower than those in OHT group (P = 0.036) and normal group (P < 0.001), while the Hcy and Cys levels in POAG and NTG groups were significantly higher (P = 0.007-0.043). The concentrations of H2S, Hcy, and Cys in glaucoma patients with different stages were not significantly different (all P > 0.05). POAG patients with longer duration of diagnosis had lower concentrations (P = 0.026, P = 0.001, P < 0.001), but no significant differences in NTG patients (all P > 0.05). The Hcy and Cys levels in NTG patients showed negative but weak correlations with mean deviation (r = -0.450, P = 0.047; r = -0.478, P = 0.033). All these concentrations showed significant but poor diagnostic values in POAG-Normal group [area under curve (AUC) = 0.642-0.721, P < 0.05]. The H2S level showed poor diagnostic power in POAG-OHT group (AUC = 0.657, P < 0.01). Conclusion: Decreased levels of H2S and increased levels of Hcy and Cys may be associated with glaucoma, especially in POAG. However, the H2S/Hcy metabolic pathway is not sufficiently sensitive to be used as a reliable biomarker in glaucoma.

Evaluation of dynamic thiol-disulfide homeostasis in glaucoma patients and the correlation with retinal nerve fiber layer analysis.

PURPOSE: The aim of this study was to evaluate thiol/disulfide homeostasis and ischemia-modified albumin levels with primary open-angle glaucoma, ocular hypertension, and control group; also to interpret the correlation between these biochemical parameters and retinal nerve fiber layer analysis. MATERIAL AND METHODS: In a prospective cross-sectional study, 30 primary open-angle glaucoma cases, 30 ocular hypertension cases, and 30 control subjects were included in the study. Native thiol, total thiol, and disulfide measurements and disulfide/native thiol, disulfide/total thiol, and native thiol/total thiol ratios were evaluated as thiol-disulfide homeostasis. Albumin and ischemia-modified albumin parameters were also evaluated. All cases underwent detailed ophthalmologic examination including visual acuity, retinal nerve fiber layer via optical coherence tomography, intraocular pressure, and central corneal thickness measurements and visual field analysis by 24-2 Swedish Interactive Threshold Algorithm (SITA) Standard visual field test. RESULTS: Primary open-angle glaucoma group had significantly higher ischemia-modified albumin values than ocular hypertension and control group (p < 0.001). Native thiol and total thiol values of control group were statistically higher than those of primary open-angle glaucoma and ocular hypertension groups. The correlation between the temporal retinal nerve fiber layer value and ischemia-modified albumin, disulfide/native thiol, and disulfide/total thiol values of the primary open-angle glaucoma patients included in the study was moderate correlation in negative direction (r = -0.46, r = -0.39, r = -0.39, respectively), whereas there was a statistically significant moderate correlation in positive direction between the native thiol/total thiol values (r = 0.39) (p < 0.05). CONCLUSION: These findings have reinforced the role of oxidative stress in the etiopathogenesis of primary open-angle glaucoma, suggesting that the thinning retinal nerve fiber layer may be associated with oxidative stress in favor of prooxidant shift.

Observation and characterization of microvascular vasomotion using erythrocyte mediated ICG angiography (EM-ICG-A).

A clinical method for characterizing the state of micro-vasculature vasomotion is demonstrated, based on observing in capillaries the dynamics of autologously re-injected erythrocytes containing ICG dye. Since a manifestation of vasomotion is transient erythrocyte pausing, vasomotion state within a field of capillaries is characterized by an histogram plot of the number of paused erythrocytes as a function of pause duration during a fixed period of observation, then the ratio of long-pausing to short-pausing erythrocytes was calculated. The method was first applied to the posterior pole retinal vasculatures of anesthetized-monkey eyes, and normal vasomotion state during air-breathing was compared to the state induced by O2-breathing, known to cause mild arteriolar vasoconstriction in the mature eye. Subsequently, the effects of other antagonists to normal arteriolarvasotonia state (long-standing experimentally-induced ocular hypertension and branch-vein occlusion, as well as tissue edema) were similarly characterized and the results compared to those obtained during baseline air-breathing. The feasibility of applying the histogram characterization of vasomotion state to human eyes and skin was also preliminarily explored.

Postprandial Glucose as a Risk Factor for Elevated Intraocular Pressure.

The aim of this study was to investigate the association between postprandial glucose and intraocular pressure in a relatively healthy population. We examined 1,439 adults getting a health check-up in a health promotion center at Tri-Service General Hospital (TSGH) in Taiwan between 2012 and 2013. All participants underwent examinations to measure metabolic variables and intraocular pressure. Multiple linear regression analyses were performed to assess the relationship between postprandial glucose and intraocular pressure. The levels of postprandial glucose were divided into quartiles with subjects in the lowest quartile being regarded as the reference group to perform quartile-based analysis. Covariate adjustment was designed for three models for further analysis. Subjects with higher quartiles of postprandial glucose level had a higher systolic blood pressure, a greater waist circumference and an elevated fasting glucose level (all p < 0.001). The ß coefficient with adjusted covariates showed a significant positive association between postprandial glucose and intraocular pressure. The trends of intraocular pressure across increasing quartiles of postprandial glucose were statistically significant (all p for trend < 0.001). Thus, higher levels of postprandial glucose positively correlated with elevated intraocular pressure.

[Elemental composition of aqueous humour and blood serum at various levels of intraocular pressure]. / Elementnyi sostav vlagi perednei kamery i syvorotki krovi pri razlichnom urovne vnutriglaznogo davleniya.

AIM: To conduct a comparative study of element concentrations in the aqueous humour of human eye and blood serum at various levels of intraocular pressure (IOP). MATERIAL AND METHODS: The chemical composition of biological fluids was studied in two equal groups (33 patients/33 eyes each): group 1 - primary open-angle glaucoma (POAG) with decompensated IOP and group 2 - normal IOP (the controls). Sampling of the aqueous humour and blood was done during surgical procedures, namely, penetrating glaucoma surgery (group 1) and cataract phacoemulsification (group 2). Blood was taken from the cubital vein and centrifuged to obtain the supernatant for further analysis. The samples were studied with Zeiss EVO LS10 scanning electron microscope (SEM) equipped with Oxford X-Max50 energy dispersive spectrometer. RESULTS: In both groups, regardless of the IOP level, Na and K concentrations were found to be constantly higher in the aqueous humour than the blood serum. The ratio of Na concentrations in the aqueous humour and serum (measured in mmol/l) was 1.51/1.30 at normal IOP and 1.49/1.31 at decompensated IOP. The ratio of K concentrations was 0.11/0.03 and 0.12/0.03, respectively. Concentrations of N and S in the aqueous humour were higher in the group with decompensated IOP. CONCLUSION: Regardless of the IOP level, Na and K concentrations were found to be constantly higher in the aqueous humour than the blood serum. IOP elevation was accompanied by an increase in N and S concentrations in the aqueous humour.

Low serum testosterone and increased diastolic ocular perfusion pressure: a risk for retinal microvasculature.

BACKGROUND: Low levels of testosterone in men and changes in retinal microvascular calibre are both associated with hypertension and cardiovascular disease risk. Sex hormones are also associated with blood flow in microvascular beds which might be a key intermediate mechanism in the development of hypertension. Whether a direct association between endogenous testosterone and retinal microvascular calibre exists is currently unknown. We aimed to determine whether testosterone is independently associated with ocular perfusion via a possible association with retinal vascular calibre or whether it plays only a secondary role via its effect on blood pressure in a bi-ethnic male cohort. PROBANDS AND METHODS: A total of 72 black and 81 white men (28-68 years of age) from the follow-up phase of the Sympathetic activity and Ambulatory Blood Pressure in Africans (SABPA) study were included in this sub-study. Ambulatory pulse pressure and intraocular perfusion pressures were obtained, while metabolic variables and testosterone were measured from fasting venous blood samples. Retinal vascular calibre was quantified from digital photographs using standardised protocols. RESULTS: The black men revealed a poorer cardiometabolic profile and higher pulsatile pressure (>50 mm Hg), intraocular pressure and diastolic ocular perfusion pressure than the white men (p≤0.05). Only in the white men was free testosterone positively associated with retinal calibre, i.e. arterio-venular ratio and central retinal arterial calibre and inversely with central retinal venular calibre. These associations were not found in the black men, independent of whether pulse pressure and ocular perfusion pressure were part of the model. CONCLUSIONS: These results suggest an independent, protective effect of testosterone on the retinal vasculature where an apparent vasodilatory response in the retinal resistance microvessels was observed in white men.

Steady-state levels of retinal 24S-hydroxycholesterol are maintained by glial cells intervention after elevation of intraocular pressure in the rat.

PURPOSE: Our previous studies suggested that CYP46A1 and 24S-hydroxycholesterol (24SOH) may be associated with glaucoma. Loss of CYP46A1-expressing retinal ganglion cells is involved in the activation of glia, and therefore possibly in the disbalance of cholesterol. In this context, the purpose of our present work was to emphasize the glial and longitudinal CYP46A1 expression after an interventional glaucoma-related stress triggered by elevated intraocular pressure (IOP). METHODS: Sprague-Dawley rats were submitted to laser photocoagulation of the trabecular meshwork, limbus and episcleral veins in one eye to induce elevated IOP. Rats were euthanized at days 3, 14, 30 and 60 (n = 10 per time-point), and 24SOH was measured in plasma and retina by gas chromatography-mass spectrometry. CYP46A1 was quantified by Western blotting. Glial activation was assessed by glial fibrillary acidic protein immunoreactivity in Western blots and retinal cryosections. RESULTS: Sustained high IOP was observed in experimental eyes from day 1 to day 21. Plasma MCP-1 and ICAM-1, quantified using multiplex assay kits, were increased at day 3. Glial activation was observed bilaterally at all time-points, at lower levels in contralateral eyes than in experimental eyes. In experimental retinas, CYP46A1 expression showed a transient increase at day 3 and then returned to baseline. Plasma and retinal 24SOH peaked at day 14 and 30, respectively. CONCLUSIONS: These data show that CYP46A1 expression was induced early in response to retinal stress but remained constant at late time-points, reinforcing the constitutive role of CYP46A1 in maintaining cholesterol balance in neuronal tissues.

Changes of serum calcium, phosphorus, and parathyroid hormone concentrations and ocular findings among patients undergoing hemodialysis.

There are various reports of ocular abnormalities in metabolic disorders. This study was done with the aim to investigate the relationships between the amounts of serum calcium, phosphorus, and parathyroid hormone concentrations and ocular findings in patients undergoing hemodialysis. Fifty eight patients with end stage renal failure undergoing hemodialysis were randomly selected and enrolled in this prospective study. Demographic data, history of diabetes mellitus and hypertension, and duration of hemodialysis were recorded. Serum calcium, phosphorus, alkaline phosphatase (ALP), and parathyroid hormone (PTH) concentrations were measured. Also, blood urea nitrogen (BUN) and weight of the patient was measured just before and three minutes after the hemodialysis. Patients also underwent a complete ocular examination including visual acuity, intraocular pressure (IOP), biomicroscopic examination, and fundoscopy. In univariate analysis, adverse relationships were found between the ocular hypertension and ALP concentration (P = 0.017) and also between the visual acuity and phosphorus concentration (P = 0.033). However, in multivariate regression analysis and with regard to the patients' characteristics and medical history in a multivariate model, no relationships were found between ocular findings and serum calcium, phosphorus, ALP, and PTH concentrations. No relationships were found between the serum concentrations of calcium, phosphorus, ALP, and PTH and ocular findings in patients with end stage renal failure undergoing hemodialysis.

Investigation into the vasospastic mechanisms in the pathogenesis of glaucomatous neuropathy.

UNLABELLED: Spasm of blood vessels supplying the optic nerve head is considered one of possible ischaemic mechanisms of glaucomatous optic neuropathy. PURPOSE: The aim of the study was to evaluate the role of two potent and long-acting vasoconstrictors: endothelin-1 (ET-1) and neuropetide Y (NPY) in the pathogenesis of glaucoma by: 1) measurement of plasma ET-1 and NPY concentrations in primary open-angle glaucoma (POAG) patients with high intraocular pressure (HTG patients) and with normal intraocular pressure (NTG patients) at baseline and following peripheral exposure to cold (cold-pressor test), 2) assessment whether changes, if any, in the plasma concentrations of both peptides following the cold-pressor test correlate with visual field defects. MATERIAL AND METHODS: The study was conducted in three groups of subjects: 1) HTG patients, 2) NTG patients and 3) controls. All subjects were young and free from any cardiovascular disorders. ET-1 and NPY concentrations in the plasma were measured by radioimmunoassay (ET-1: Amersham International UK, NPY: Peninsula Laboratories INC). The cold-pressor test was performed by immersing the whole hand in ice-cold water (4 degrees C) for 2 minutes. Visual fields were examined using standard automated perimetry (Octopus 101, G-2 programme, normal strategy). RESULTS: In the NTG patients the mean baseline plasma ET-1 concentration was significantly lower and the mean baseline plasma NPY concentration significantly higher compared to controls. On the other hand, there were no statistically significant differences in the mean baseline peptide levels between the HTG patients and the control subjects. After the cold-pressor test the mean ET-1 concentrations considerably increased in the three groups. The highest increase was seen in the NTG group and it was statistically significant compared to the HTG group and controls. Following the cold-pressor test the mean NPY concentration was significantly decreased in the NTG group, but remained virtually unchanged in the HTG group and controls. In the NTG patients, significant increase in the mean ET-1 concentration and decrease in the mean NPY concentration seen after the cold-pressor test were accompanied by a significant decrease in the mean MS (mean retinal sensitivity) value in the second eye examined after the cold-pressor test, but no correlation was found between changes in the MS values and changes in the ET-1 and NPY concentrations. There were no significant changes in the mean MS values after cold-pressor test in the HTG patients and controls. CONCLUSIONS: Our findings suggest abnormal neuro-endothelial mechanisms of vascular tone control in NTG patients, related to the effects of ET-1 and NPY, secondary to endothelial dysfunction and to dysregulation of the autonomic nervous system. These abnormalities may involve potentiation of the vasoconstrictive effects of both ET-1 and NPY leading to the optic nerve head ischaemia and subsequent development of visual field defects in the course of normal-tension glaucoma.

[Expression of glucocorticoid receptors alpha and beta in mononuclear cells of peripheral blood in patients with glucocorticoid-induced ocular hypertension].

OBJECTIVE: To study the expression of glucocorticoid receptors (alpha and beta) in mononuclear cells of peripheral blood (PBMCs) in patients with glucocorticoid-induced ocular hypertension (GIOH) and the relationship between of the expression of GRalpha and GRbeta in PBMCs and its susceptibility to GIOH. METHODS: Case control study. Thirty-two patients with anaphylactic conjunctivitis were enrolled in this study. All of whom were received topical application of 0.1% dexamethasone. The patients with the elevation of intraocular pressure (IOP) over 8 mm Hg(1 mm Hg = 0.133 kPa) or higher within two weeks were defined as GIOH and the others were considered as control group. There were no statistical difference in sex, average age, and baseline IOP between two groups. Each group consisted of sixteen patients. GRalpha and GRbeta mRNA (relative value) in PBMCs were detected with semi-quantitative reverse transcriptional polymerase chain reaction (RT-PCR), GRalpha and GRbeta protein (positive ratio) in PBMCs examined with fluorescent labelling flow cytometry. RESULTS: The GRalpha mRNA/GAPDH ratio of GIOH group was significantly (t = 3.872, P < 0.05) higher than that of control group (1.152 +/- 0.057 vs 1.048 +/- 0.031). The GRbeta mRNA/GAPDH of GIOH group was lower than that of control group's (1.055 +/- 0.034 vs 1.063 +/- 0.035), but was not statistically different (t = 0.419, P > 0.05). GRalpha positive percentage was significantly (t = 8.513, P < 0.01) higher in PBMCs of GIOH group than that of the control group (93.10 +/- 7.35)% vs (46.00 +/- 13.11)%, whereas GRbeta positive percentage was significantly (t = 4.842 P < 0.01) lower in PBMCs of GIOH group than that in control group (12.50 +/- 4.18)% vs (23.83 +/- 3.92)%. CONCLUSIONS: The higher expression of GRalpha in PBMCs in patients may have an implication of susceptibility to GIOH and warrant further investigation.

Dorzolamide-timolol combination and retinal vessel oxygen saturation in patients with glaucoma or ocular hypertension.

AIMS: To examine whether the addition of dorzolamide to timolol monotherapy influences oxygen saturation in the human retina. METHODS: Non-invasive spectrophotometric retinal oximetry was used to measure oxygen saturation in retinal vessels. Twenty patients with open-angle glaucoma (11) and ocular hypertension (9) were recruited. The patients were randomised into receiving timolol monotherapy or dorzolamide-timolol combination for an 8-month test period, followed by a second test period, before which the patients switched treatments. Oximetry measurements were performed at 2-month intervals during each period. Of the 20 patients, 13 followed the study protocol into the second test period, and 10 managed all study visits. RESULTS: The oxygen saturation in retinal vessels was stable within the test periods. The mean arteriolar saturation was 96 (2)% (mean (SD)) during timolol monotherapy and 97 (2)% during dorzolamide-timolol combination therapy (p = 0.17, all patients pooled, n = 13). Corresponding values in venules were 66 (5)% during timolol monotherapy and 65 (6)% during dorzolamide-timolol therapy (p = 0.13). Patients who started on dorzolamide-timolol combination showed a significant reduction in arteriolar (98 (2)% to 95 (2)%, p<0.01) and venular saturation (69 (5)% to 66 (6)%, p<0.05) when changing to timolol monotherapy. CONCLUSION: Adding dorzolamide to timolol monotherapy has a minimal effect, but going from dorzolamide-timolol combination to timolol alone lowered arteriolar and venular oxygen saturation. The retinal oxygen saturation measurements show a high degree of stability over an extended period of time. Previous studies have suggested increased retinal and optic nerve blood flow with dorzolamide. Unchanged oxygen saturation and increased blood flow would indicate increased oxygen delivery to the retina.

Sera of glaucoma patients show autoantibodies against myelin basic protein and complex autoantibody profiles against human optic nerve antigens.

BACKGROUND: The aim of this study was to gain more information about the possible immunological mechanisms in glaucoma. We analyzed the complex autoantibody patterns against human optic nerve antigens in sera of patients with glaucoma and tried to identify important antigens. METHODS: Sera of 133 patients were included: healthy control subjects (n = 44), primary open-angle glaucoma (n = 44), and normal tension glaucoma patients (n = 45). The sera were tested against Western blots of human optic nerve, and antibody bands were visualized with chloronaphthol. IgG antibody patterns were analyzed by multivariate statistical techniques, and the most significant antigens were identified by mass spectrometry (Maldi-TOFTOF). RESULTS: All subjects, even healthy ones, showed different and complex antibody patterns. Glaucoma groups showed specific up- and down-regulations of antibody reactivities compared to the control group. The multivariate analysis of discriminance found significant differences (P < 0.05) in IgG antibody profiles against human optic nerve antigens between both glaucoma groups and healthy subjects. The identified antigens include: myelin basic protein (up-regulated in the POAG group), glial fibrillary acidic protein (down-regulated in the glaucoma groups), and vimentin (down-regulated in the glaucoma groups in comparison to controls). CONCLUSIONS: Using human optic nerve antigen, we were able to demonstrate that complex IgG autoantibody patterns exist in sera of patients with glaucoma. Large correlations between the given and our previous studies using bovine optic nerve antigens could be seen. Furthermore, anti-myelin basic protein antibodies, which can also be detected in patients with multiple sclerosis, were found in sera of glaucoma patients.

Decreased plasma cortisol in response to intramuscular ACTH in ocular hypertensives and primary open-angle glaucomas.

PURPOSE: To determine if there is a difference in response of the adrenal gland to intramuscular adrenocorticotropic hormone (ACTH) between normals and ocular hypertensives (OHs) plus primary open-angle glaucomas (POAGs) without pigmented angles. METHODS: Intramuscular ACTH was given to 29 normals and 24 OH plus POAG hospitalized in a Clinical Study Unit. Blood samples were obtained at baseline (0 hours) before administration of intramuscular ACTH and 4, 8, and 24 hours after administration of intramuscular ACTH for analysis of plasma cortisol/body mass index (BMI). RESULTS: The OH plus POAG group showed lower cortisol/BMI values compared with the normal group at 4, 8, and 24 hours with a significantly lower peak/BMI value (P=0.030). Multivariate analyses with the peak plasma cortisol/BMI level as the dependent variable showed that a lower peak plasma/BMI was associated with the OH plus POAG group. Also, a lower peak plasma cortisol/BMI level was associated with a lower 0-hour cortisol/BMI (Log). CONCLUSIONS: Compared with normals, the OH plus POAG subjects showed lower plasma cortisol levels in response to intramuscular ACTH. This observation suggests adrenal suppression in the OH plus OAG group.

Systemic high-sensitivity C-reactive protein levels in normal-tension glaucoma and primary open-angle glaucoma.

PURPOSE: To determine the systemic high-sensitivity C-reactive protein (hsCRP) level in patients with normal tension glaucoma (NTG) and primary open-angle glaucoma (POAG). MATERIALS AND METHODS: With the exclusion of patients with cardiovascular and other systemic diseases, 40 patients with NTG, 40 with POAG, and 40 normal controls were enrolled in this study. Each patient underwent blood sampling for hsCRP, biochemistry, and lipid profile analysis. RESULTS: Each group had similar demographic parameters including the age, sex, body mass index, heart rate, and blood pressure. There was no statistically significant difference in the hsCRP and biochemistry results between the 3 groups. The lipid profile exhibited a mild elevation in the patients with POAG. CONCLUSIONS: Our data revealed no difference in the hsCRP level between NTG, POAG, and normal controls after exclusion of patients with cardiovascular and other systemic diseases. Systemic vascular inflammation may not be a major cause in the pathogenesis of glaucoma in those without histories of cardiovascular diseases.

Plasma thymulin and nerve growth factor levels in patients with primary open angle glaucoma and elevated intraocular pressure.

BACKGROUND: The objective was to measure the plasma concentrations of thymulin and nerve growth factor (NGF) in a group of patients with primary open angle glaucoma (POAG) and compare them with age- and sex-matched normal controls. METHODS: Twenty-eight patients newly diagnosed with POAG who were not undergoing treatment were compared with the same number of age- and sex-matched healthy controls. Blood samples were drawn into heparinized tubes and plasma samples were collected for the determination of the concentrations of thymulin and NGF, using specific enzyme-linked immunosorbent assay (ELISA). The Student's t test was used to perform the necessary statistical analysis of the results. RESULTS: Seventeen women and 11 men were enrolled in each of the two groups (study and control), with a mean age of 63.7 (SD 10.3) years in the former and 63.3 (SD 9.6) years in the latter. There was a highly significant (p<0.001) elevation in the thymulin levels in POAG patients compared with the control group. However, no significant difference was observed when comparing the plasma NGF levels. CONCLUSION: This is the first report to measure plasma thymulin levels in glaucoma patients. The significant results point the possible role of this immunomodulator in the pathogenesis of primary open angle glaucoma. The potential role of NGF seems to be less likely. These findings warrant further investigation.

Decreased response of plasma cortisol to intravenous metyrapone in ocular hypertension and primary open-angle glaucoma.

PURPOSE: To determine if there is a difference in response to metyrapone, which blocks the conversion of 11-deoxycortisol to cortisol in the adrenal gland between normals and ocular hypertensives (OH) plus primary open-angle glaucomas (POAG) without pigmented angles. METHODS: Intravenous metyrapone was given to 20 normals and 15 ocular hypertensives plus primary open-angle glaucomas without pigmented angles. Blood samples were obtained at 4, 6, and 8 hours after administration of intravenous metyrapone for analyses of 11-deoxycortisol and cortisol. RESULTS: The ocular hypertensives plus primary open-angle glaucoma group showed significantly lower cortisol values compared with the normal group at 6 hours (P = 0.002) but not at 4 or 8 hours. There were no significant differences between the two groups for 11-deoxycortisol values at 4, 6, or 8 hours. The percent decrease of plasma cortisol from baseline was significantly greater for the ocular hypertensives plus open-angle glaucoma group compared with the normals at 4 hours (P = 0.010) and 6 hours (P = 0.0004). Significant negative correlations were observed for the total group of subjects between levels of plasma cortisol at 6 hours and intraocular pressure, worse eye (P = 0.029), percent area of cupping, worse eye (P = 0.045), pallor, worse eye (P = 0.001), and visual field loss, worse eye (P = 0.048), so that the less the plasma cortisol, the greater the abnormality of the glaucomatous parameters. Multivariate analyses with the 6-hour plasma cortisol level as the dependent variable showed that the only significant (P = 0.0004) independent variable was the percent area of pallor, worse eye, associated with a smaller level of plasma cortisol at 6 hours. Similarly, the multiple regression models using the percent change from baseline of the 6-hour plasma cortisol value showed a significant association of larger percent decreases of plasma cortisol in the ocular hypertensives plus open-angle glaucoma compared with the normals. CONCLUSIONS: The ocular hypertensives plus primary open-angle glaucoma subjects show greater adrenal inhibition to metyrapone in the synthesis of cortisol from 11-deoxycortisol compared with normals. This observation suggests an adrenal abnormality in the ocular hypertensive plus primary open-angle glaucoma subjects.

Comparison of carteolol plasmatic levels after repeated instillations of long-acting and regular formulations of carteolol 2% in glaucoma patients.

BACKGROUND: A new long-acting (LA) formulation of carteolol 2% instilled once daily has been shown to provide a therapeutic effect similar to that of the regular formulation of carteolol 2% instilled twice daily. This study was designed to test whether the new formulation reduces the systemic delivery of carteolol. METHODS: In this double-masked, randomised, intra-subject comparative study, 23 patients with bilateral primary open-angle glaucoma or bilateral ocular hypertension received sequentially, according to the randomised order of administration, each of the 2 following treatments: carteolol 2% LA once daily for 2 months and carteolol 2% regular twice daily for 2 months. Treatments were instilled in both eyes throughout the study period. At the end of each period of treatment, blood samples were taken immediately before the last morning instillation (residual time), then 30 min, 1 h, 2 h and 4 h after this instillation in order to measure the carteolol plasma concentrations. RESULTS: The mean values of maximal plasma concentration (C(max)), residual level and area under the curve obtained following carteolol 2% LA treatment were significantly lower than the values obtained after carteolol 2% regular treatment (mean+/-SD): C(max) (ng/ml): 1.72+/-0.85 versus 3.64+/-3.65; residual level (ng/ml): 0.70+/-0.58 versus 1.80+/-0.84; area under the curve (ng/mlxh): 5.50+/-2.66 versus 10.27+/-5.46. Regarding safety, two drug-related, non-serious adverse events were reported in the LA group: one case of moderate, superficial, punctate keratitis and one case of "bitter taste in the throat." Both treatments appeared to be well tolerated. CONCLUSIONS: The data from this study showed that the systemic delivery of carteolol is lower for the once-daily LA formulation than for the regular twice-daily formulation. Consequently, long-acting carteolol eye-drops should reduce the risk of beta-blocking systemic side effects.

Association between low plasma levels of ophthalmic timolol and haemodynamics in glaucoma patients.

OBJECTIVES: The aims of the study were to assess the correlation between the plasma concentration of ophthalmic timolol and cardiovascular parameters, and the influence of timolol on advanced haemodynamic variables, such as stroke (SI), cardiac (CI) and systemic vascular resistance (SVRI) indices and arterial pulse wave velocity (PWV). METHODS: Twenty-five glaucoma or ocular hypertensive patients were treated with 0.5% aqueous and 0.1% hydrogel formulations of timolol using a randomised, double-masked, crossover, multicentre design. All the patients were subjected to passive head-up tilt, electrocardiography, exercise test and measurement of plasma concentration of timolol. In the analysis, the data on the two treatments were combined, and the Spearman correlation coefficients between the plasma level of timolol and physiological effects were calculated. RESULTS: During the head-up tilt test before rising the bed up, the resting heart rate (HR; R=-0.52, P=0.001) and PWV (R=-0.34, P=0.04) were inversely correlated with timolol level. In the upright position, ophthalmic timolol effectively suppressed the rise in HR (R=-0.36, P=0.03). The SI did not change with timolol concentration, while CI diminished as timolol concentration rose (R=-0.39, P=0.02). The SVRI correlated with timolol concentration (R=0.38, P=0.02). In the exercise test, correlation between HR and plasma level of timolol steadily grew stronger as the load increased, reaching R=-0.60 (P<0.0001) at the maximum load. Systolic and diastolic arterial pressures were not associated with the timolol concentration. CONCLUSION: The plasma concentration of ophthalmic timolol correlates with several haemodynamic effects. As HR decreases, SVRI increases and blood pressure is kept unchanged.

Immobilization stress induces elevation of intraocular pressure in rabbits.

The aim of this study was to test whether immobilization and intravenous volume load as stressors influence the intraocular pressure in rabbits. Rabbits were immobilized for 1 h in a horizontally placed plastic tube with an internal diameter of 13.2 cm and a length of 33.2 cm. After immobilization, rabbits received rapid intravenous drip infusion of 5% glucose solution, 20 ml/kg of body weight, in 5 min. The intraocular pressure immediately after immobilization (11.2 +/- 3.0 mm Hg; mean and standard deviation) was significantly higher compared to control rabbits without immobilization (9.2 +/- 1.0 mm Hg, Student's t test, p = 0.0462). This difference became significantly larger when volume load was exerted on both groups of rabbits (22.7 +/- 5.6 versus 16.4 +/- 2.2 mm Hg, p = 0.0067). Serum levels of cortisol, adrenaline, and noradrenaline were significantly elevated after immobilization (p = 0.0002, p = 0.0271, p = 0.0296, respectively). Venous pressure of the ear tended to increase in rabbits immediately after immobilization (15.8 +/- 3.1 mm Hg) compared with control rabbits (8.5 +/- 2.3 mm Hg), and the difference became significant when volume load was exerted on both groups of rabbits (20.8 +/- 7.4 versus 9.2 +/- 4.8 mm Hg, p = 0.0211). In conclusion, we clearly demonstrated that physical stress due to immobilization, especially in combination with volume load, increased intraocular pressure in rabbits.