Glaucoma is a group of eye conditions that damage the optic nerve, often linked to elevated pressure inside the eye, potentially leading to vision loss. Narrow angle glaucoma, also known as angle-closure glaucoma, is a specific form of this condition.
Understanding Narrow Angle Glaucoma
The eye continuously produces a clear fluid called aqueous humor, which nourishes the eye and helps maintain its shape. This fluid typically drains out of the eye through a network of channels located in the angle between the iris (the colored part of the eye) and the cornea (the clear front surface of the eye).
In narrow angle glaucoma, this drainage angle is constricted, impeding aqueous humor outflow. When fluid cannot drain properly, pressure builds inside the eye, damaging the optic nerve. This condition can manifest as chronic narrow angle glaucoma, where the angle gradually narrows, or as acute angle-closure glaucoma, which is a sudden and often painful blockage considered a medical emergency. Symptoms of acute angle-closure glaucoma can include severe eye pain, headache, blurred vision, and seeing halos around lights, while chronic forms may have less noticeable symptoms in early stages.
The Hereditary Link
Narrow angle glaucoma has a hereditary component; a family history increases an individual’s risk. This indicates a predisposition influenced by genetic factors, not direct inheritance like eye color. Individuals inherit specific anatomical features of their eyes from their parents, which can make them more susceptible to narrow angles.
Inherited anatomical characteristics often include shorter eye length or a shallower anterior chamber (the space between the cornea and iris). Farsighted (hyperopic) individuals often have smaller eyes with shallower anterior chambers, leading to narrower drainage angles. Research continues to identify specific genes, but narrow angle glaucoma results from a complex interplay of multiple genes rather than a single defect.
Risk is higher for first-degree relatives (parents, siblings, children) of affected individuals, with some studies showing significantly elevated risk for siblings. This familial tendency underscores the importance of understanding one’s family eye health history.
Other Risk Factors
Beyond genetics, several other factors increase the likelihood of developing narrow angle glaucoma. Advancing age is a risk factor; the eye’s lens grows throughout life, potentially pushing the iris forward and narrowing the angle. It is more common in individuals over 60.
Ethnicity also plays a role, with certain groups having higher prevalence due to specific eye structures. Individuals of East Asian and Inuit heritage, for example, are more prone due to naturally narrower anterior chamber drainage angles. Women also have a slightly higher risk than men, possibly due to sex-linked differences in eye anatomy.
Certain medications can trigger or worsen narrow angle glaucoma by causing pupil dilation, pushing the iris forward and blocking the drainage angle. These include some cold and flu remedies containing decongestants or antihistamines, certain antidepressants, and some medications used for anxiety, asthma, or bladder control. Even dilating eye drops used during exams can pose a risk in susceptible individuals. Existing eye conditions like hyperopia (farsightedness) and cataracts can also contribute to angle narrowing.
Screening and Proactive Steps
Regular, comprehensive eye examinations are important for anyone, especially those with identified risk factors. An eye care professional can perform specific diagnostic tests to assess the drainage angle and optic nerve health.
Gonioscopy is a standard method for visualizing and evaluating the eye’s drainage angle. This procedure involves using a special mirrored lens to determine if the angle is open or narrow. Other tests may include tonometry to measure eye pressure, ophthalmoscopy to examine the optic nerve for damage, and optical coherence tomography (OCT) for detailed imaging of the nerve.
If a very narrow angle is detected, prophylactic laser iridotomy may be recommended. This laser procedure creates a small opening in the iris, allowing fluid to flow more freely and reducing the risk of a sudden angle-closure attack. Early detection and timely intervention are important for managing narrow angle glaucoma and preserving vision.