Postural Orthostatic Tachycardia Syndrome (POTS) is a complex disorder of the autonomic nervous system, primarily resulting in orthostatic intolerance. This condition prevents the body from properly regulating blood flow upon standing, causing an abnormally high increase in heart rate. The resulting circulatory dysfunction affects multiple systems, and POTS can significantly affect vision. These visual disturbances are a recognized part of the syndrome, frequently linked to the body’s failure to maintain adequate blood supply to the upper body when gravity pulls blood downward. Understanding the mechanisms behind these symptoms is the first step toward finding effective management strategies.
Specific Visual Disturbances Associated with POTS
Temporary blurring is a common visual symptom, often experienced immediately upon moving to an upright position. This orthostatic blurring can make reading or recognizing faces momentarily impossible as the eyes struggle to focus while circulation stabilizes. Patients also frequently report transient visual obscuration, which can manifest as “graying out” or “blacking out,” known medically as pre-syncope. This sensation signals that the brain’s visual processing centers are losing sufficient blood supply.
Tunnel vision is another symptom, where peripheral sight narrows drastically, leaving only a small central field of view. This phenomenon is thought to be linked to a functional disturbance in the frontal lobe, which controls peripheral visual exploration. Sensitivity to light (photophobia) is a frequent complaint, sometimes related to the autonomic nervous system’s influence on pupillary function. Visual snow, a persistent static-like visual disturbance across the entire field of vision, is sometimes attributed to dysfunction in the brainstem or occipital lobes due to inadequate blood flow.
Physiological Mechanism Linking POTS and Sight
The visual symptoms in POTS are a direct consequence of the body’s inability to counteract the effects of gravity on blood volume. When a person with POTS stands up, the autonomic nervous system fails to trigger reflex vasoconstriction in the lower body’s blood vessels. This failure causes an excessive volume of blood to pool in the abdomen and lower extremities. Consequently, the amount of blood returning to the heart decreases dramatically.
This reduced venous return translates to a lower cardiac output, meaning less oxygenated blood is being pumped to the brain and eyes. This state, known as cerebral hypoperfusion, starves the visual cortex and the brainstem of the blood flow needed to function optimally. The brainstem, responsible for regulating gaze stabilization and other involuntary eye movements, can become dysfunctional, contributing to symptoms like blurred vision or difficulty focusing.
The eyes are also susceptible to fluctuations in blood flow, governed by the Ocular Perfusion Pressure (OPP). OPP is the difference between the pressure of the blood entering the eye and the intraocular pressure. In POTS, the drop in systemic blood pressure upon standing can lower the OPP, compromising the blood flow to the optic nerve and retina, despite the body’s attempts at autoregulation. When this pressure is lowered, the visual system temporarily falters, resulting in symptoms like transient blackouts or graying of vision before a near-fainting episode.
Managing and Mitigating POTS-Related Visual Issues
Managing POTS-related visual issues focuses on non-pharmacological interventions aimed at increasing circulating blood volume and reducing blood pooling. A primary strategy involves increasing fluid intake (often two to four liters of water daily) and following a high-sodium diet (sometimes up to 10 grams of salt per day). This combination helps expand plasma volume, ensuring more blood returns to the heart, brain, and eyes.
Compression garments are another effective tool, particularly waist-high stockings and abdominal binders. These garments apply external pressure (typically 30 to 40 mmHg) to the lower body and midsection. This pressure prevents blood from pooling in the legs and splanchnic circulation, improving venous return and blood flow to the upper body. Wearing these garments before standing can help stabilize circulation and mitigate the onset of orthostatic visual symptoms.
Specific physical counter-maneuvers can be used immediately upon feeling the onset of visual symptoms like blurring or tunnel vision. Actions such as crossing the legs, tightly squeezing leg muscles, or rapidly squatting down can immediately raise blood pressure by activating the muscle pump. These maneuvers briefly increase the return of blood to the heart and can abort a pre-syncopal episode and clear the visual field. Medications that increase blood volume or promote vasoconstriction may be prescribed by a specialist to manage the underlying circulatory issue. Individuals experiencing persistent or unusual vision changes should consult an ophthalmologist to rule out any independent ocular pathology.