From the Guidelines
Pheochromocytoma can potentially cause elevated intraocular pressure (IOP) due to the excessive catecholamines secreted by the tumor, which can affect ocular blood flow and aqueous humor dynamics. The mechanism involves alpha-adrenergic stimulation, which can decrease aqueous humor outflow and increase episcleral venous pressure, both contributing to IOP elevation [ 1 ]. Additionally, the systemic hypertension associated with pheochromocytoma can directly impact ocular perfusion pressure and potentially worsen IOP control.
Key Points to Consider
- Pheochromocytoma is a rare tumor of the adrenal glands that secretes excessive catecholamines, leading to episodes of hypertension [ 1 ].
- Patients with pheochromocytoma who experience visual symptoms or have glaucoma risk factors should undergo regular ophthalmologic evaluation.
- Management typically focuses on treating the underlying pheochromocytoma, usually through surgical removal of the tumor, which often resolves the secondary hypertension and may improve IOP control.
- Alpha-blockers like phenoxybenzamine or doxazosin, commonly used to manage pheochromocytoma symptoms before surgery, may also help reduce IOP by counteracting the catecholamine effects on ocular tissues.
Treatment and Management
The decision to begin treatment to lower IOP in patients with pheochromocytoma should be based on the ophthalmologist’s analysis of the examination results, risk assessment, and evaluation of the patient and the patient’s preferences [ 1 ]. The number and severity of risk factors present, the prognosis, management plan, and likelihood that therapy, once started, can be long term, should be discussed with the patient and, when feasible, with the patient’s family. Treatment with alpha-blockers, such as doxazosin, may be beneficial in reducing IOP and managing pheochromocytoma symptoms [ 1 ].
From the Research
Pheochromocytoma and Intraocular Pressure
- Pheochromocytoma is a rare, mostly benign catecholamine-producing tumor of chromaffin cells of the adrenal medulla or of a paraganglion 2.
- The typical clinical manifestations of pheochromocytoma are sustained or paroxysmal hypertension, severe headaches, palpitations, and sweating resulting from hormone excess 2.
- However, there is evidence to suggest that pheochromocytoma can cause high intraocular pressure (IOP) 3.
- A case study reported a patient with pheochromocytoma presenting with bithalamic infarction, dementia, and elevated intraocular pressure, which improved after adrenelectomy 3.
- The exact mechanism by which pheochromocytoma causes high IOP is not clearly understood, but it may be related to the excess release of catecholamines, which can stimulate α and β adrenoreceptors and lead to various clinical manifestations, including increased IOP 4.
Clinical Presentation and Screening
- Pheochromocytomas can produce a wide range of clinical manifestations, including arterial hypertension, tachycardia, sweating, headache, and other symptoms secondary to the stimulation of α and β adrenoreceptors 4.
- Screening for pheochromocytoma is recommended in patients with paroxysmal, resistant, or early-onset arterial hypertension, and in cases with symptoms suggestive of catecholamine hypersecretion 4.
- The diagnosis of pheochromocytoma depends mainly on the demonstration of catecholamine excess by 24-h urinary catecholamines and metanephrines or plasma metanephrines, and localization by computed tomography scan and magnetic resonance imaging of the adrenal glands and abdomen 2.
Treatment and Management
- The treatment of pheochromocytoma typically involves surgical excision, and perioperative management requires the administration of selective α1-adrenergic blocking agents followed by β-adrenergic blockade 5.
- In cases where pheochromocytoma is associated with high IOP, glaucoma treatment may be necessary to suppress high intraocular pressure, in addition to antihypertensive and antidiabetic medication 3.