Primary open angle glaucoma begins in middle-aged and elderly patients with minimal symptoms that progressively worsen. The angle of the anterior chamber characteristically remains open throughout the clinical course of the disorder.
Epidemiology: Primary open angle glaucoma is by far the most common form of glaucoma and accounts for over 90% of adult glaucomas. The incidence of the disorder significantly increases beyond the age of 40, reaching a peak between the ages of 60 and 70. Its prevalence among 40-year-olds is 0.9% as compared to 4.7% among patients over the age of 50.
There appears to be a genetic predisposition for primary open angle glaucoma. Over one- third of glaucoma patients have relatives with the same disorder.
Patients with a positive family history are at greater risk of developing the disorder.
Etiology (See also physiology and pathophysiology of aqueous humor circulation): The cause of primary open angle glaucoma is not known, although it is known that drainage of the aqueous humor is impeded. The primary lesion occurs in the neuroretinal tissue of the optic nerve as compression neuropathy of the optic nerve.
Symptoms: The majority of patients with primary open angle glaucoma do not experience any subjective symptoms for years. However, a small number of patients experience occasional unspecific symptoms such as headache, a burning sensation in the eyes, or blurred or decreased vision that the patient may attribute to lack of eyeglasses or insufficient correction. The patient may also perceive rings of color around light sources at night, which has traditionally been regarded as a symptom of angle closure glaucoma.
H Primary open angle glaucoma often does not exhibit typical symptoms foryears. Regular examination by an ophthalmologist is crucial for early diagnosis.
Primary open angle glaucoma can be far advanced before the patient notices an extensive visual field defect in one or both eyes.
It is crucial to diagnose the disorder as early as possible because the prognosis for glaucoma detected in its early stages is far better than for advanced glaucoma. Where increased intraocular pressure remains undiagnosed or untreated for years, glaucomatous optic nerve damage and the associated visual field defect will increase to the point of blindness.
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