Low-tension Glaucoma Patients Research Articles

Visualising structural and functional characteristics distinguishing between newly diagnosed high-tension and low-tension glaucoma patients.

To determine whether there are quantifiable structural or functional differences that can distinguish between high-tension glaucoma (HTG; intraocular pressure [IOP] > 21 mm Hg) and low-tension glaucoma (LTG; IOP ≤ 21 mm Hg) at diagnosis. This was a retrospective, cross-sectional study. Clinical results of one eye from 90 newly diagnosed HTG and 319 newly diagnosed LTG patients (117 with very-low-tension glaucoma [vLTG; ≤15 mm Hg] and 202 with middling LTG [mLTG; >15 mm Hg, ≤21 mm Hg]) were extracted, which included relevant demographic covariates of glaucoma, quantitative optical coherence tomography (including the optic nerve head, retinal nerve fibre layer and ganglion cell-inner plexiform layer) measurements and standard automated perimetry global metrics. We used binary logistic regression analysis to identify statistically significant clinical parameters distinguishing between phenotypic groups for inclusion in principal component (PC) (factor) analysis (PCA). The separability between each centroid for each cohort was calculated using the Euclidean distance (d(x,y)). The binary logistic regression comparing HTG and all LTG identified eight statistically significant clinical parameters. Subsequent PCA results included three PCs with an eigenvalue >1. PCs 1 and 2 accounted for 21.2% and 20.2% of the model, respectively, with a d(x,y)=0.468, indicating low separability between HTG and LTG. The analysis comparing vLTG, mLTG and HTG identified 15 significant clinical parameters, which were subsequently grouped into five PCs. PCs 1 and 2 accounted for 24.1% and 17.8%, respectively. The largest separation was observed between vLTG and HTG (d(x,y)=0.581), followed by vLTG and mLTG (d(x,y)=0.435) and lastly mLTG and HTG (d(x,y)=0.210). Conventional quantitative structural or functional parameters could not distinguish between pressure-defined glaucoma phenotypes at the point of diagnosis and are therefore not contributory to separating cohorts. The overlap in findings highlights the heterogeneity of the primary open-angle glaucoma clinical presentations among pressure-defined groups at the cohort level.

Types of reaction to pilocarpine in patients with low-tension glaucoma

PURPOSE. To determine the types of reaction to pilocarpine in patients with low-tension glaucoma (LTG) and study the nature of fluid outflow along the main pathways in different types of reaction to pilocarpine.METHODS. The observation group included 21 people (42 eyes) with LTG aged 51 to 80 years (average age 68±9.8 years). The criteria for inclusion in the study were emmetropic refraction and no previous laser and surgical interventions on the examined eye. The anterior chamber angle corresponded to medium–wide or wide according to the classification by A.P. Nesterov. The initial stage of LTG was established in 16 eyes, developed stage — 12 eyes, advanced stage — 14 eyes.The examination was carried out both in patients with newly diagnosed glaucoma and in patients with previously established diagnosis who received hypotensive drug therapy; in the latter case the patients were recommended to cease instillations of hypotensive drugs 10–14 days prior to the examination.RESULTS. Among the studied LTG patients, positive pilocarpine test was registered in 5 eyes (12%), negative — in 6 eyes (14%), and paradoxical — in 31 eyes (74%).The obtained data revealed no statistically significant differences in the initial values of anterior chamber depth, lens thickness and axial eye length between patients with paradoxical and positive reactions to pilocarpine. Therefore, there are no anatomical prerequisites for the development of a particular type of reaction to the pilocarpine test in the studied eyes.The ease of outflow coefficient (EOC) for the drainage pathway is significantly reduced in patients with positive reaction to pilocarpine, which in absolute numbers approaches normal values. In these patients the drainage outflow reserves are preserved.In persons with paradoxical reaction to pilocarpine, EOC for the drainage pathway is significantly reduced and is low in absolute numbers. Deterioration of the outflow along the uveoscleral pathway in pilocarpine instillations leads to elevated intraocular pressure.CONCLUSION. The majority of patients with low-tension glaucoma have a paradoxical reaction to the pilocarpine test. The sufficiently high sensitivity of the sample allows recommending it as a diagnostic test for this type of glaucoma.Different types of reaction to pilocarpine in patients with low-tension glaucoma are associated with the intensity of intraocular fluid outflow over the drainage and uveoscleral pathways.

A study of connective tissue metabolites in biological fluids of patients with various types of glaucoma

PURPOSE. To quantify the content of connective tissue metabolites reflecting the exchange of its main components in biological fluids in low tension glaucoma (LTG) and primary open-angle glaucoma (POAG), and to conduct a comparative analysis of the obtained data. METHODS. The studies were conducted in 33 patients with low tension glaucoma aged 51 to 80 years old (mean age 69 ± 10.4 years), 20 patients with POAG aged 53 to 80 years old (mean age 67 ± 10.1 years) and 15 clinically healthy volunteers aged 52 to 78 years old (mean age 68 ± 9.2 years). The protein components of the fibrous part of the connective tissue were analyzed for daily excretion of oxyproline in urine by the method involving para-Dimethylamin-obenzaldehyde modified by P.N. Sharaev. Serum glycosaminoglycans (GAG) were studied by analyzing carbohydrate components of connective tissue. The concentration of GAG in the blood serum was determined by the colorimetric method, using Dische's carbazole reaction. RESULTS. The amount of GAG in the blood serum of LTG patients was 3.26 ± 1.57 mmol/L, while in the control group consisting of clinically healthy volunteers — 2.92 ± 1.25 mmol/L. The differences were not statistically significant (p > 0.1). The amount of daily excretion of oxyproline in the urine of LTG patients was 17.17 ± 8.64 mmol/day, and in the group of clinically healthy individuals — 13.96 ± 5.61 mmol/day. The differences were statistically significant (p < 0.05). The amount of GAG in the blood serum of POAG patients was 3.97 ± 1.17 mmol/L. The differences in relation to LTG were statistically significant (p < 0.05). The amount of daily excretion of oxyproline in the urine of POAG patients was 32.71 ± 19.79 mmol/day. The differences were statistically significant in relation to LTG (p < 0.05). The amount of GAG and oxyproline in biological fluids tends to increase with the advancement of LTG and POAG. CONCLUSION. Destruction processes in the connective tissue do occur in LTG, but are less pronounced in comparison to POAG and more pronounced in comparison to healthy individuals. The indicator that most clearly reflects the activity of destructive processes in the connective tissue is the daily excretion of oxyproline in urine.

Obstructive sleep apnea as a risk factor for primary open angle glaucoma and ocular hypertension in a monocentric pilot study

BackgroundBoth glaucoma and obstructive sleep apnea (OSA) are widespread diseases. OSA may presumably partly cause or worsen glaucoma, although the etiopathogenesis is unclear. Here we analyze for the first time the possible association between different glaucoma phenotypes and OSA.Methods110 patients (47 females, 63 males; median age 64.3 years, median BMI 26.62 kg/m2) with suspected glaucoma and without any prior diagnosis of OSA were prospectively studied by one-night home sleep apnea testing (HSAT), 101 of the patients were analyzed. HSAT parameters, like apnea hypopnea index (AHI) and oxygen desaturation index as well as opthalmological parameters like intraocular pressure (IOP) and mean defect depth (MD) were collected. Moreover, HSAT results were compared across four phenotypic groups: primary open angle glaucoma (POAG), low-tension-glaucoma (LTG), ocular hypertension (OH), and controls.ResultsThere was no strong correlation between IOP or MD and AHI. BMI, age and gender did not differ between groups. Significant differences between POAG and LTG were found for all HSAT parameters. The AHI showed the most prominent group difference (Wilcoxon-Kruskal-Wallis rank sum test was highly significant with chi2 = 22, df = 3 p < 0.0001) with severely lower event rates in the LTG (9.45/h) compared to POAG (22.7/h) and controls (21.9/h; p < 0.0001 and 0.02, respectively). Highly significant differences were found between the four groups regarding AHI (Chi2 = 22, df = 3, p < 0.0001) with significantly lower events per hour in the LTG compared to POAG (Hodges-Lehmann = − 13.8, 95% CI (− 18.6 – − 8.8; p < 0.0001) and to controls (Hodges-Lehmann = 12.1, 95% CI -19.9 – − 2.4; p < 0.02). Severe and moderate OSA was more prevalent in POAG (69.8%) and OH (33.3%) than in LTG (9%). The effect of the glaucoma phenotype on the AHI was more prominent in females (p = 0.0006) than in males (p = 0.011).ConclusionAlthough physical endpoints, such as MD and IOP, do not correlate with AHI, there was a strong correlation between the POAG and OH clinical glaucoma phenotypes and the AHI. Further studies should investigate the necessity to test routine screening for OSA by HSAT in patients with diagnosed POAG and OH. Besides, some characteristics of LTG differed widely from other glaucoma types and controls. LTG patients had a significantly lower rate of OSA compared to other glaucoma types and even controls. This might be due to a different pathogenesis of LTG.Trial registrationRetrospectively registered at DRKS (nr. S00021201) on April 9th 2020.

Identification of the Most Accurate Spectral-domain Optical Coherence Tomography Parameters in Eyes With Early High-Tension and Low-Tension Glaucoma.

The aim of the study was to compare the diagnostic ability of macular ganglion cell complex (GCC) and peripapillary retinal nerve fiber layer (pRNFL) thickness in high-tension glaucoma (HTG) and low-tension glaucoma (LTG). Glaucoma was defined as glaucomatous optic neuropathy and reproducible visual field defects. Patients were classified as having LTG if untreated intraocular pressure was ≤21 mm Hg on 2 different occasions. Only eyes with early glaucoma (mean deviation <-6 dB) were included. All patients underwent spectral-domain optical coherence tomography (SDOCT) imaging. A total of 56 normal subjects, 64 HTG patients, and 35 LTG patients were enrolled. Overall, after adjusting for mean deviation and age, the average pRNFL thickness in eyes with LTG was 18.7 µm thinner than in eyes with HTG (17% difference, P<0.01). In the HTG group, no significant difference was found between areas under the receiver operating characteristic curve (AUCs) for average GCC and average pRNFL thicknesses (0.77 vs. 0.68, P=0.06). In the LTG group, average pRNFL thickness had a significantly larger AUC compared with average GCC thickness (0.95 vs. 0.81, P<0.001). Comparing AUCs between HTG and LTG groups, although the average GCC had similar AUCs in both groups (P=0.47), the average pRNFL thickness had a significantly larger AUC in the LTG group (P<0.001). In eyes with early glaucoma, the pRNFL thickness scan seems to be a more accurate SDOCT protocol to identify those with LTG compared with the GCC thickness scan.

Cerebral blood flow in glaucoma patients.

Glaucomatous damage has been described as a slowly progressive neuronal degenerative process along the visual pathway. Decreased cerebral and ocular blood flow as well as impaired vascular autoregulation has been identified in glaucoma and have been shown to correlate with visual field loss. In low-tension glaucoma patients, diffuse cerebral ischemic changes have been detected through magnetic resonance imaging. Given these findings, it seems that for some patients, glaucomatous damage may be the ocular manifestation of a more widespread vascular abnormality involving the brain rather than a separate process isolated only to the eye and its immediate vasculature.

Distribution of optineurin sequence variations in an ethnically diverse population of low-tension glaucoma patients from the United States.

Previous studies have suggested that Optineurin (OPTN) sequence variants contribute to low-tension glaucoma (LTG) in ethnically homogeneous populations. The purpose of this study is to evaluate the prevalence of OPTN sequence variants in an ethnically diverse population of LTG patients from the United States, and to describe the phenotype of patients with OPTN sequence variants preferentially found in LTG patients. Genomic DNA purified from 67 LTG patients was screened for DNA sequence variants located in the exons and flanking introns of the OPTN gene using high-performance liquid chromatography analysis and direct genomic DNA sequencing. Eighty-six primary open-angle glaucoma probands and 100 control patients were also analyzed. Nine OPTN DNA sequence variants were identified in this patient population including the 2 previously identified heterozygous nonsynonymous single-nucleotide polymorphisms in exons 4 and 5. Four LTG patients with severe disease and positive family history of glaucoma, were found to have DNA sequence changes not found in primary open-angle glaucoma probands or control individuals including the previously reported E50K variation. The results of this study support the rare association of OPTN sequence variants with familial forms of LTG. The E50K mutation seems to be associated with a severe form of LTG, and although rare, the identification of this sequence variant in patients at risk may help direct appropriate therapy.

Migraine and glaucoma: an epidemiologic survey of French ophthalmologists.

Glaucoma is a common ocular disorder; a high intraocular pressure is observed in the majority of glaucoma (HIOPG) cases, but some patients have low-tension glaucoma (LTG). In the literature, some works link LTG and migraine, which is speculative of a potential role of a vasospastic factor or diathesis common to migraine and LTG. Using a standardized questionnaire based on International Headache Society (IHS) criteria, we investigated 954 glaucoma patients; 320 (33.5%) described a headache (migraine or tension-type headache) and 240 (25.1%) presented the IHS criteria for migraine. Migraine prevalence was not significantly different between HIOPG and LTG patients (22.8% and 32%, respectively) in this study.

Reduced ocular pulse amplitude in low tension glaucoma is independent of vasospasm.

A vascular basis for the pathogenesis of primary open angle glaucoma has been postulated for many years. Defects in the regulation of ocular blood flow may be the initiating factor in this group of multifactorial diseases. This study was designed to evaluate the effect of vasospasm on ocular pulse amplitude (OPA) in low tension glaucoma (LTG) patients. OPA, using the Langham Ocular Blood Flow (OBF) System, applanation intraocular pressure (IOP), systemic blood pressure and heart rate were measured and vasospasm was determined by a fingernail capillary blood flow test. OPA (mmHg) in the LTG patients with a vasospastic reaction (LTG-V, 1.4 +/- 0.1, n = 17) was not significantly (p > 0.09) different when compared with non-vasospastic LTG patients (LTG-NV, 1.5 +/- 0.2, n = 15) but was significantly (p < 0.001) reduced in LTG-V and LTG-NV patients when compared with matched healthy control subgroups (2.3 +/- 0.2 and 2.4 +/- 0.3, respectively). IOP (mmHg) in LTG-V (13.3 +/- 0.4) and LTG-NV (13.2 +/- 0.5) patient groups was not significantly (p > 0.05) different when compared with each other, but was significantly (p < 0.05) lower when compared with matched control subgroups (15.0 +/- 0.3 and 15.2 +/- 0.4, respectively). Haemodynamic parameters were not significantly different from controls. The abnormality in choroidal perfusion indicated by a reduction in OPA in all LTG patients is unrelated to the presence or absence of vasospasm.

Correlation Between the Visual Field Indices and Heidelberg Retina Tomograph Parameters

We wished to determine whether a relationship exists between Heidelberg retina tomograph (HRT) parameters and the visual field indices. One eye was randomly chosen from 59 normal patients [normal visual field and normal optic nerve head (ONH) and intraocular pressure (IOP) < 21 mm Hg], 64 ocular hypertensive patients (normal visual field and normal OHN and IOP > 22 mm Hg), 124 high-tension glaucoma patients (abnormal visual field and/or abnormal optic nerve and IOP > 22 mm Hg) and 47 low-tension glaucoma patients (abnormal visual field and or optic disc and IOP < 21 mm Hg). All the patients were examined with Humphrey Perimeter, program 30-2, and HRT. Findings were assessed by analysis of variance, Pearson's correlation coefficient, and multiple linear regression. Among all subjects, we noted a statistically significant correlation (Pearson's r, p < 0.001) between cup area, cup/disc area ratio, rim area, rim volume, cup shape measure, and retinal nerve fiber layer cross-section area with mean deviation and corrected pattern SD. Multiple linear regression analysis demonstrated that rim area was the most important predictor of mean deviation and corrected pattern SD. The presence of significant correlations between some HRT parameters, such as rim area and cup shape measure and visual field indices, suggests that these HRT parameters could be good indicators of the degree of glaucomatous ONH damage.

Differences in optic discs in low-tension glaucoma patients with relatively low or high pressures

Differences in optic discs in low-tension glaucoma patients with relatively low or high pressures

Influence of physical exercise and nifedipine on ocular pulse amplitude.

Ocular pulse amplitude (OPA) was measured to investigate the influence of peripheral vasoconstriction and vasodilation on choroidal perfusion in healthy volunteers and to determine whether low OPA in low-tension glaucoma (LTG) patients is associated with a vasospastic reaction and its response to the calcium channel blocker nifedipine. OPA was determined using the Langham ocular blood flow (OBF) system, applanation intraocular pressure (IOP), systemic blood pressure, and heart rate were measured, and ocular perfusion pressure was calculated before and after exercise and smoking in 12 otherwise nonsmoking, healthy volunteers and prior to and for 3 months after initiation of nifedipine therapy in 32 LTG patients with and without a vasospastic reaction as manifested by a nailfold capillary blood flow test. Exercise significantly (P < 0.05) increased heart rate, systolic blood pressure and ocular perfusion pressure, while it significantly (P < 0.05) reduced IOP and diastolic blood pressure. However, OPA was not significantly (P > 0.1) affected by changes in these parameters. Smoking significantly (P < 0.05) increased systolic and diastolic blood pressure, heart rate, and ocular perfusion pressure but did not significantly (P > 0.09) alter OPA. There were two distinct LTG subtypes, with and without a vasospastic reaction. Only those with a vasospastic reaction showed a significant (P < 0.001) increase in OPA after 3 months of nifedipine treatment, while all other parameters tested were not significantly altered. Despite affecting ocular and systemic perfusion parameters, exercise and smoking did not alter OPA, suggesting functional isolation, i.e. autoregulation of the choroidal and/or ophthalmic artery circulation in healthy volunteers. Low OPA in LTG was increased by nifedipine only in vasospastic LTG patients, suggesting different, vasotonus-related pathologies. Calcium channel blockers and other vasodilators may be useful in vasoreactive LTG patients with reduced OPA.

Low-Tension Glaucoma: A Comparative Study With Retinal Ischemic Syndromes and Anterior Ischemic Optic Neuropathy

ABSTRACT In low-tension glaucoma (LTG), nerve-fiber-bundle defects are assumed to result from ischemia of the choroidal branches of the posterior ciliary arteries, due either to local vascular changes or, presumably, hemodynamically occlusive carotid artery disease. To study the possible hemodynamical origin of LTG, we examined and compared, clinically and by ultrasound (continuous-wave Doppler and duplex-scanning), the extracranial carotid arteries of (1) 21 patients (34 eyes) with LTG, (2) 48 patients (49 eyes) with retinal ischemic syndromes (RISI, and (3) 15 patients (17 eyes) with anterior ischemic optic neuropathy (AION). High-grade stenoses and occlusions of the internal carotid arteries ipsilateral to the affected eyes were significantly more frequent in the RIS patients (17 of 49) than in the LTG patients (2 of 34; P &lt; .01) and the AION patients (0 of 17; P &lt; .01). Among our relatively small group of LTG patients, we found no striking evidence supporting a hemodynamic origin of LTG.

Calcium Channel Blockers in the Management of Low-tension and Open-angle Glaucoma

Fifty-six patients with either open-angle or low-tension glaucoma who were concurrently taking calcium channel blockers were compared to similar groups not taking such medications for a mean follow-up period of 3.4 years. Serial stereoscopic optic nerve photographs and visual fields of all patients were evaluated for evidence of glaucomatous progression. In patients with low-tension glaucoma, there was a significant difference in the progression of visual field defects, with only two of 18 eyes (11%) of patients taking calcium channel blockers, compared to ten of 18 eyes (56%) of controls showing new visual field defects. Similarly, low-tension glaucoma patients taking calcium channel blocker therapy demonstrated no evidence of progressive optic nerve damage, compared to eight of 18 control eyes (44%). In contrast, patients with open-angle glaucoma taking calcium channel blockers showed no marked difference in the progression of glaucoma, compared to controls. These findings suggest that calcium channel blockers may be useful in the management of low-tension glaucoma.

Finger blood flow in patients with low tension glaucoma and primary open-angle glaucoma.

Finger blood flow was studied by means of laser Doppler flowmetry in 12 patients with low tension glaucoma (LTG), 12 patients with primary open-angle glaucoma (POAG) and 12 normal subjects. Baseline flow, flow after immersion of the hand in warm water (+40 degrees C), and flow after exposure of the hand in cold water (+4 degrees C) were measured. Statistically significant differences were not found in each flow between the three groups of the patients (p greater than 0.05). Vasospastic response to warm and cold water was observed in 25% of LTG patients, 17% of POAG patients, and 25% of normal subjects. There was no significant difference between LTG, POAG, and normal subjects in finger blood flow.

Hemodynamic variables in progressive and non‐progressive low tension glaucoma

Systemic blood pressure and medications for different general diseases were retrospectively examined in 30 low-tension glaucoma patients. Thirty patients with POAG were used as controls. LTG was divided into a progressive and non-progressive form on basis of the course of the disease. Systemic blood pressure was higher in POAG and the progressive form of LTG than in the non-progressive LTG. There was twice as much antihypertensive medication in LTG than POAG patients.

Unequal Intraocular Pressure and Its Relation to Asymmetric Visual Field Defects in Low-tension Glaucoma

Fifty-nine low-tension glaucoma patients were reviewed with respect to asymmetry of intraocular pressure (IOP) and visual field defects. In the presence of unequal IOP the visual field damage is almost always greater on the side with higher mean IOP. However, only 13 of 47 patients with asymmetric visual field defects had a mean IOP difference between the two eyes of greater than or equal to 1 mmHg. Although in the case of IOP asymmetry visual field damage is greater in the eye with higher mean IOP, other factors must also play an important role in the development of visual field defects in low-tension glaucoma.

Co-existence of empty sella syndrome and low tension glaucoma.

In 15 low-tension glaucoma patients computed tomography of the head was re-evaluated in order to find the possible empty-sella syndrome. Fourteen CT-scans were normal, and empty sella was found in one patient with progressive low tension glaucoma. The possible role of empty sella syndrome in glaucomatous visual field defects is discussed.

A Comparison of the Blue Color Mechanism in Highand Low-tension Glaucoma

Twenty-five eyes of 25 high-tension glaucoma patients and 25 eyes of 25 low-tension glaucoma patients matched for similar visual field defects had their spectral increment threshold measured. Patients with high-tension glaucoma showed significant losses in both chromatic and achromatic sensitivities when compared with low-tension glaucoma patients. The results support the hypothesis that there may be different mechanisms of damage in glaucoma.

Response of Blood Flow to Warm and Cold in Normal and Low-Tension Glaucoma Patients

We measured blood flow in the finger in 38 control subjects with normal ocular findings without migraine, 13 control subjects with normal ocular findings with classic migraine, 17 patients with low-tension glaucoma with classic migraine, and 29 patients with low-tension glaucoma without migraine. Three blood flow measurements were recorded: one at baseline, one after immersion in warm water (40 C), and one after ten seconds' exposure to cold water (4 C). The mean baseline flow and the mean flow after exposure to cold was lower in patients with low-tension glaucoma (P = .013 and P less than .001, respectively).