Glaucoma risk factors: Difference between revisions
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===Primary Angle Closure Glaucoma=== | ===Primary Angle Closure Glaucoma=== | ||
*'''Race''' : The prevalence in patients older than 40 years depends on race: it is 0.1%-0.6% in whites, 0.1%-0.2% in blacks, 2.1%-5.0% in the Inuit, 0.4%-1.4% in East Asians, 0.3% in the Japanese, and 2.3% in a mixed ethnic group in South Africa. The underlying cause of these differences is due the difference in the biometric parameters (anterior chamber depth, axial length) of the different white and Inuit populations. The increased incidence in the Chinese and East Asian populations are not due to biometric parameters. In most cases angle closure presents as an asymptomatic chronic disease without an acute attack. | *'''Race''' : The prevalence in patients older than 40 years depends on race: it is 0.1%-0.6% in whites, 0.1%-0.2% in blacks, 2.1%-5.0% in the Inuit, 0.4%-1.4% in East Asians, 0.3% in the Japanese, and 2.3% in a mixed ethnic group in South Africa. The underlying cause of these differences is due the difference in the biometric parameters (anterior chamber depth, axial length) of the different white and Inuit populations. The increased incidence in the Chinese and East Asian populations are not due to biometric parameters. In most cases angle closure presents as an asymptomatic chronic disease without an acute attack. | ||
*'''Ocular | *'''Ocular Anatomy''': Patients who are the risk of developing primary angle closure have smaller anterior segments and short axial lengths. The most important risk factor an eye to angle closure are a shallow anterior chamber, a thick lens, increased anterior curvature of the lens, a short Axial length, and a small corneal diameter and radius of curvature. The anterior chamber depth (ACD) of less than 2.5 mm predisposes patients to primary angle closure, whereas most patients with primary angle closure have an ACD of less than 2.1 mm. While primary PAS seem to be uncommon with an ACD of greater than 2.4 mm, there is a strong correlation of increasing PAS formation with an ACD shallower than 2.4 mm. However, despite these generalizations, angle closure still occurs with deep anterior chambers in some cases. | ||
*'''Age''': The prevalence of ACG increases with each decade after 40 years of age. This increased prevalence has been explained by the increasing thickness and forward movement of the lens with age, and the resultant increase in iridolenticular contact. PACG is rare in persons younger than 40 years, and the etiology of angle closure in young individuals is most often related to structural or developmental anomalies rather than pupillary block. | *'''Age''': The prevalence of ACG increases with each decade after 40 years of age. This increased prevalence has been explained by the increasing thickness and forward movement of the lens with age, and the resultant increase in iridolenticular contact. PACG is rare in persons younger than 40 years, and the etiology of angle closure in young individuals is most often related to structural or developmental anomalies rather than pupillary block. | ||
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Rohan Bir Singh, M.B.B.S.[2]
Risk factors
Primary Open Angle Glaucoma
- Age : The risk increases with the increase in age.The visual field defects were 7 times more likely to progress in patients aged 60 years or older than in those younger than 40 years. Although increased lOP with age has been observed in many populations and may account for part of the relationship between age and glaucoma, studies in Japan have shown a relationship between glaucoma and age even with no increase in lOP in the population.
- Race : The prevalence of POAG is 3 to 4 times greater in black persons and Hispanic persons than in non-Hispanic white individuals. Blindness from glaucoma is at least 4 times more common in blacks than in whites. Glaucoma is more likely to be diagnosed at a younger age and likely to be at a more advanced stage at the time of diagnosis in black patients than in white patients.The Baltimore Eye Survey found that the prevalence of glaucoma increases dramatically with age, particularly among black persons, exceeding 11% in those aged 80 years or older.
- Family History : A positive family history is also a risk factor for POAG. The relative risk of POAG is increased approximately 3.7-fold for individuals who have a sibling with POAG.
- Myopia : The evidence supports an association between POAG and myopia. The concurrence of POAG and myopia cause difficulty in diagnosis and management of POAG. There is an increased difficulty in evaluation of the optic disc is particularly complicated in highly myopic eyes that have tilted discs or posterior Staphyloma. The magnification of the disc due to the myopic refractive error interferes with optic disc evaluation. Myopia-related retinal abnormalities can cause visual field defects apart along with glaucoma. High refractive error may also make it difficult to perform accurate perimetric measurement and to interpret visual field abnormalities.
- Diabetes Mellitus : The role of diabetes mellitus in causing POAG is still controversial. Though some studies have found diabetes plays a significant role in the disease, other studies have not found diabetes to be major risk factor.
- Hypertension : The systemic hypertension is associated with a low risk of the presence of glaucoma in younger patients and with an increased risk in older (>65 years) patients. It is considered that with advancing age, the adverse effects of chronic hypertension on the optic nerve microcirculation may lead to the nerve's susceptibility to the development of glaucomatous optic neuropathy. Many studies demonstrate that lower ocular perfusion pressure is a strong risk factor for the development of glaucoma, independent of lOP alone. Some research groups define ocular perfusion pressure as blood pressure (systolic, diastolic, or mean arterial) minus lOP. The overtreatment of systemic hypertension may be a contributing factor to glaucoma progression in some cases and hence, should be avoided.
- Retinal vein occlusion : The patients with central retinal vein occlusion may lead to an elevated lOP and glaucoma. In some case, there may be presentation of preexisting POAG or other types of glaucoma. After CRVO, patients may develop angle-closure glaucoma or, at a later stage, neovascular glaucoma. The comorbidity is due to elevated lOP in susceptible individuals, thus are at risk of developing CRVO.
- Sleep apnea
- Thyroid disorders
- Hypercholesterolemia
- Migraine
- Raynaud Phenomenon
Primary Angle Closure Glaucoma
- Race : The prevalence in patients older than 40 years depends on race: it is 0.1%-0.6% in whites, 0.1%-0.2% in blacks, 2.1%-5.0% in the Inuit, 0.4%-1.4% in East Asians, 0.3% in the Japanese, and 2.3% in a mixed ethnic group in South Africa. The underlying cause of these differences is due the difference in the biometric parameters (anterior chamber depth, axial length) of the different white and Inuit populations. The increased incidence in the Chinese and East Asian populations are not due to biometric parameters. In most cases angle closure presents as an asymptomatic chronic disease without an acute attack.
- Ocular Anatomy: Patients who are the risk of developing primary angle closure have smaller anterior segments and short axial lengths. The most important risk factor an eye to angle closure are a shallow anterior chamber, a thick lens, increased anterior curvature of the lens, a short Axial length, and a small corneal diameter and radius of curvature. The anterior chamber depth (ACD) of less than 2.5 mm predisposes patients to primary angle closure, whereas most patients with primary angle closure have an ACD of less than 2.1 mm. While primary PAS seem to be uncommon with an ACD of greater than 2.4 mm, there is a strong correlation of increasing PAS formation with an ACD shallower than 2.4 mm. However, despite these generalizations, angle closure still occurs with deep anterior chambers in some cases.
- Age: The prevalence of ACG increases with each decade after 40 years of age. This increased prevalence has been explained by the increasing thickness and forward movement of the lens with age, and the resultant increase in iridolenticular contact. PACG is rare in persons younger than 40 years, and the etiology of angle closure in young individuals is most often related to structural or developmental anomalies rather than pupillary block.