Narrow angle glaucoma is an eye condition where the iris and cornea are positioned too closely. This anatomical configuration restricts the natural drainage of fluid from the eye, leading to a buildup of pressure. If left unmanaged, this condition can damage the optic nerve and potentially result in vision loss. This article informs individuals with narrow angle glaucoma about factors, medications, and situations to approach with caution, helping prevent a sudden, damaging increase in eye pressure known as an acute angle-closure attack.
Why Certain Things Must Be Avoided
The reason certain factors must be avoided in narrow angle glaucoma relates to the eye’s drainage system. The eye produces aqueous humor, which drains through the drainage angle, where the iris meets the cornea. In narrow angle glaucoma, this angle is already constricted.
Pupil dilation can cause the iris to bunch up, blocking this narrow drainage angle. When the drainage pathway is obstructed, aqueous humor cannot exit efficiently, leading to a rapid rise in intraocular pressure (IOP). This sudden increase in pressure is termed an acute angle-closure attack, which can cause significant damage to the optic nerve. Preventing excessive pupil dilation is a central strategy in managing narrow angle glaucoma and avoiding these attacks.
Medications to Approach with Caution
Many medications, both prescription and over-the-counter, can induce pupil dilation or affect the drainage angle, increasing the risk of an acute angle-closure attack in individuals with narrow angles. It is important to always inform all healthcare providers, including doctors and pharmacists, about a narrow angle glaucoma diagnosis before starting any new medication.
Anticholinergic medications are a class to consider, as they block acetylcholine, a chemical messenger that influences pupil size. These are often found in common remedies such as over-the-counter cold and allergy medications containing antihistamines like diphenhydramine. Some antispasmodics, tricyclic antidepressants, and bladder control medications, such as tolterodine and oxybutynin, also possess anticholinergic properties.
Sympathomimetic drugs, which mimic the effects of adrenaline, can also cause pupil dilation. Examples include decongestants like pseudoephedrine and phenylephrine, often found in cold and flu remedies. Certain antidepressants, particularly older tricyclic antidepressants such as amitriptyline and imipramine, carry a higher risk due to their anticholinergic effects. Some selective serotonin reuptake inhibitors (SSRIs), like fluoxetine and paroxetine, have also been associated with an increased risk.
Motion sickness medications, such as scopolamine patches, can have anticholinergic properties that may induce pupil dilation. Certain topical eye drops used during eye exams are designed to dilate pupils and pose a temporary risk. Other medications that may increase risk include some antipsychotics, anti-Parkinsonian drugs, and certain medications for irritable bowel syndrome. Sulfonamide-containing drugs, like topiramate and acetazolamide, can also cause fluid shifts in the eye, potentially leading to angle closure.
Situations to Be Mindful Of
Beyond medications, certain environmental and lifestyle factors can influence pupil size and eye pressure, warranting awareness for individuals with narrow angle glaucoma. Prolonged exposure to dim lighting conditions can naturally cause the pupils to dilate to allow more light to enter the eye. This dilation can reduce the space within the drainage angle, increasing the risk of an angle-closure attack. Using adequate lighting for activities like reading, watching television, or navigating indoors can help mitigate this risk.
Emotional stress can also play a role, as severe stress may trigger physiological responses that include pupil dilation or changes in intraocular pressure. While the exact mechanisms are still being explored, managing stress through techniques like mindfulness or relaxation may contribute to overall eye health. Certain body positions, such as prolonged face-down positions, might increase intraocular pressure in some individuals, though this is generally a low risk. Maintaining good hydration is generally beneficial for overall health, including eye health.
Recognizing an Angle-Closure Emergency
Understanding the signs of an acute angle-closure emergency is important for anyone with narrow angle glaucoma, as prompt action can help prevent permanent vision loss. An acute attack manifests with sudden, severe eye pain, often accompanied by blurred vision. Individuals may also experience seeing rainbow-colored halos around lights.
Additional symptoms can include redness of the affected eye, headache, nausea, and vomiting. These systemic symptoms can lead to misdiagnosis as a neurologic or gastrointestinal issue. If any of these symptoms occur, seek immediate medical attention from an ophthalmologist or an emergency room, as timely treatment is important to preserve vision.