Risk Factor For Normal Tension Glaucoma Research Articles

CONQUERING THE AMBIGUITY OF OPTIC ATROPHY IN NORMAL TENSION GLAUCOMA: FROM MYSTERY TO MASTERY

Introduction : The dilemma in diagnosing glaucoma often arises when optic atrophy is found alongside nonspecific glaucomatous findings and normal intraocular pressure (IOP), particularly in cases of normal tension glaucoma (NTG). This gray zone often leads to doubt and misdiagnosis.
 Case Illustration : A 70-year-old man previously diagnosed with idiopathic bilateral optic atrophy complained of blurred vision in both eyes. The visual acuity was 5/5 in the right eye (RE) and hand movement in the left eye (LE). Both eyes had normal IOP, open angles with Sampaolesi lines on gonioscopy, fibrin deposits at pupillary margins, and a large cup-to-disc ratio with baring and peripapillary atrophy on funduscopy. The OCT examination revealed thinning in the ONH-RNFL, ILM-RPE, and GCL-IPL complexes. HFA revealed tunnel vision in RE and general depression in LE. The patient was suspected of having NTG. We performed BMO-MRW (less than 100 ?m in both eyes) and 24-hour ocular perfusion pressure (OPP) measurements (less than 50 mmHg at night) to support the diagnosis.
 Discussion : The BMO-MRW examination is a new parameter that can help establish the diagnosis of glaucoma. A thin BMO-MRW finding suggests that optic atrophy originates from glaucoma. It is important to perform a comprehensive examination in cases of NTG to identify risk factors and prevent the development of glaucoma. Decreased OPP to less than 50 mmHg and PEX syndrome may be risk factors for NTG.
 Conclusion : In cases of doubtful optical atrophy, it is important to consider the possibility of NTG by performing a comprehensive examination, including BMO-MRW and twenty-four hour OPP measurements.

Relationship of axial length and corneal biomechanical properties with susceptibility to unilateral normal-tension glaucoma.

Corneal biomechanics, reflecting structural vulnerabilities of the eyeball, may participate in the pathogenesis of unilateral normal-tension glaucoma. This study investigated the pathophysiology of unilateral normal-tension glaucoma using Corvis ST (OCULUS Optikgeräte GmbH) and other ocular characteristics. Eighty-three patients with normal-tension glaucoma with unilateral visual field loss and structurally unaffected fellow eyes and 111 healthy controls were included in this prospective study. Dynamic corneal response parameters, intraocular pressure measured by rebound tonometry, central corneal thickness, and axial length were assessed on the same day. Measurements were compared between affected eyes, unaffected fellow eyes, and control eyes. Risk factors for normal-tension glaucoma and unilateral involvement were the main outcome measures. A shorter first applanation time (adjusted odds ratio, 0.061; 95% confidence interval, 0.018-0.215) and a larger peak distance (adjusted odds ratio, 4.935; 95% confidence interval, 1.547-15.739) were significant risk factors for normal-tension glaucoma and were associated with greater glaucoma severity (both P < 0.001). Axial length (adjusted odds ratio, 29.015; 95% confidence interval, 4.452-189.083) was the predominant risk factor for unilateral involvement in patients with normal-tension glaucoma. The eyes with normal-tension glaucoma were more compliant than healthy eyes. Axial elongation-associated optic nerve strain may play an important role in unilateral normal-tension glaucoma with similar corneal and scleral biomechanics in both eyes.

Is stagnant cerebrospinal fluid involved in the pathophysiology of normal tension glaucoma.

Current concepts of the pathophysiology of normal tension glaucoma (NTG) include intraocular pressure, vascular dysregulation and the concept of a translaminar pressure gradient. Studies on NTG performed with cisternography demonstrated an impaired cerebrospinal fluid (CSF) dynamics in the subarachnoid space of the optic nerve sheath, most pronounced behind the lamina cribrosa. Stagnant CSF might be another risk factor for NTG.

Normal-tension glaucoma and obstructive sleep apnea syndrome: a prospective study

BackgroundToday, identified risk factors for normal-tension glaucoma (NTG) include abnormal ocular blood flow, abnormal blood coagulation, systemic hypotension, ischemic vascular disorders, and autoimmune diseases. However, pathogenesis of the condition remains unclear. On the other hand, there are also a few studies suggesting that the obstructive sleep apnea syndrome (OSAS) may compromise optic nerve head perfusion and cause glaucomatous optic neuropathy by creating transient hypoxemia and increasing vascular resistance. In this study, we evaluated the possible association between OSAS and NTG.MethodsWe recruited 24 patients with NTG and 24 age and sex matched controls who were also similar for systemic risk factors such as diabetes mellitus (DM), hypertension (HT) and hypercholesterolemia. All patients and controls underwent over-night polysomnography (PSG) for the diagnosis of OSAS and calculation of Apnea-Hypopnea Index (AHI).ResultsPatients and controls were statistically similar in terms of age, sex, gender, smoking, systemic risk factors, neck circumference and body mass index. The subjects with AHI ≥ 20 were accepted as OSAS. Ten (41.7%) of 24 patients with NTG and 3 (12.5%) of 24 controls had OSAS (p < 0.05).ConclusionsThe prevalence of OSAS was higher in patients with NTG and the difference between patient and control groups was statistically significant (p < 0.05).

Risk Factors for Normal-Tension Glaucoma Among Subgroups of Patients

To identify risk factors for normal-tension glaucoma among subgroups of patients. In 93 patients with unilateral normal-tension glaucoma, intereye comparison of baseline spherical equivalent, central corneal thickness, untreated intraocular pressure, disc area, and zone beta variables was performed among the following 4 subgroups classified according to age and visual field pattern standard deviation of the eye with glaucoma: subgroup 1 (age < or = 50 years and visual field pattern standard deviation < or = 8 dB), subgroup 2 (< or = 50 years and >8 dB), subgroup 3 (>50 years and < or = 8 dB), and subgroup 4 (>50 years and >8 dB). Fourteen, 27, 30, and 22 patients were included in subgroups 1, 2, 3, and 4, respectively. The untreated intraocular pressure in subgroup 1 (P = .005), the zone beta variables in subgroup 2 (P < .001), and both the untreated intraocular pressure (P = .010 and P = .034, respectively) and the zone beta variables (P < or = .008 and P < or = .006, respectively) in subgroups 3 and 4 were significantly greater in the eyes with glaucoma than in the normal contralateral eyes (by paired t test or Wilcoxon signed rank test). The other variables showed no significant difference between the eyes in any subgroup. The zone beta variables (and not the untreated intraocular pressure) may represent significant risk factors in young patients having normal-tension glaucoma with moderate to severe visual field loss.

Long axial length as risk factor for normal tension glaucoma

The high prevalence of normal tension glaucoma (NTG) in the Japanese requires special screening tests other than measurements of only the intraocular pressure (IOP). This study was carried out to determine whether there is a significant association between the axial length of the eye and the presence of NTG. We reviewed the medical records of all patients who were scheduled to undergo cataract surgery alone or combined with glaucoma surgery at the same time. There were 87 patients with NTG, 137 with POAG, and 978 non-glaucomatous control cases. The axial length, IOP, curvature of the anterior corneal surface, age, and gender were determined at the time of the operation. If both eyes had surgery, data from only the right eyes were analyzed. An association of these parameters with NTG and POAG was analyzed by logistic regression analysis. The three groups were analyzed for differences in the axial length using the Kruskal-Wallis test followed by the Mann-Whitney U test. The axial length was significantly associated with NTG (odds = 1.24, P = 0.002) and POAG (odds = 1.28, P = 0.001). The incidence of either POAG or NTG was significantly higher in patients with axial lengths >or=25.0 mm (odds = 2.29, P < 0.001, Fisher's exact test). The age at the time of cataract surgery was weakly but significantly correlated negatively with the axial length (r = -0.24, P < 0.001, Pearson's correlation coefficient test). Men had significantly longer axial lengths than women. Long axial lengths can be considered a risk factor for NTG and POAG, and patients with long axial lengths need to be carefully examined for glaucoma.

Headache in Normal-Tension Glaucoma Patients

Headache with or without features of migraine has been reported to be a risk factor for normal-tension glaucoma (NTG). However, it is not known whether the linkage between headache and the glaucomatous disease is independent of intraocular pressure (IOP). The purpose of this study was to compare the IOP of a group of NTG patients with headache and the IOP of a group of NTG patients without headache. The mean IOP was compared for 14 persons with and nine persons without headache in a group of 23 NTG patients. An analogous comparison was done between 13 persons with and 10 persons without headache in a group of 23 nonglaucomatous controls. Glaucoma patients and nonglaucomatous controls were uniform with regard to sex, age, and mean IOP. In NTG patients, however, those with headache had a significantly lower mean IOP than did those without headache (p = 0.0004) despite a comparable glaucomatous visual-field damage. Such a difference did not occur in nonglaucomatous patients. Headache seems to define a particular population among NTG patients.