Vision can change overnight, presenting a range of alterations from subtle, temporary shifts to more pronounced signs of underlying health issues. Understanding these reasons is important for recognizing when a change might be benign and when it signals a need for medical evaluation. The eye’s ability to focus depends on factors like the lens’s condition and the energy available to adjust it, both of which can fluctuate over short periods.
Temporary Causes of Vision Fluctuation
Several common factors can lead to temporary changes in vision, often resolving with rest or minor adjustments. Prolonged engagement with digital screens, known as digital eye strain, frequently causes temporary blurriness, discomfort, or a perceived reduction in clarity. This occurs because the eyes work harder to focus on digital text and images, leading to fatigue in the tiny muscles inside the eye and reduced blinking, which can result in dry eyes.
Dry eyes, a condition where the eyes do not produce enough lubrication, also contribute to fluctuating vision, causing blurriness that improves with blinking. Environmental factors such as high winds or dry air can accelerate tear film evaporation, leading to sudden dry eye symptoms. Poor sleep habits can also reduce tear production, contributing to mild, transient blurred vision.
Blood sugar fluctuations can impact the eye’s lens and temporarily alter vision. When blood sugar levels rise or fall, the lens can swell or shrink, leading to transient blurriness that typically resolves as blood sugar stabilizes. Certain medications can also induce sudden changes in refractive error or cause dry eyes, contributing to temporary visual disturbances.
Medical Conditions Causing Sudden Vision Changes
Medical conditions can manifest as sudden vision changes, often requiring prompt medical attention. Retinal detachment, a condition where the retina lifts away from underlying tissue, can cause new flashes of light, an increase in floating specks or “floaters,” and a sensation of a curtain or shadow moving across the field of vision. This occurs when fluid passes through a retinal tear, separating the retina from its blood supply.
Acute angle-closure glaucoma is characterized by a rapid increase in eye pressure, leading to sudden eye pain, redness, blurred vision, and the appearance of halos around lights. This happens when the drainage angle in the eye becomes suddenly blocked, preventing fluid from exiting. Optic neuritis, an inflammation of the optic nerve, often presents with sudden vision loss, pain when moving the eye, and a reduction in color vision, commonly affecting one eye.
A stroke or transient ischemic attack (TIA) can cause sudden, painless vision loss in one eye or double vision, as these events can disrupt blood flow to the brain or eye. Diabetic retinopathy, a complication of diabetes, involves damage to the blood vessels in the retina, which can lead to sudden blurriness or vision loss due to fluid leakage or abnormal blood vessel growth. Wet macular degeneration involves the leakage of fluid or blood in the macula, causing sudden vision loss and distorted central vision. Certain eye infections, such as keratitis or uveitis, can lead to sudden blurriness, pain, or discomfort due to inflammation or damage to eye structures.
When to Seek Medical Attention
Any sudden and unexplained change in vision warrants evaluation by an eye care professional. Immediate medical attention is necessary for symptoms such as sudden, painless loss of vision in one or both eyes, as this can indicate a stroke or central retinal artery occlusion. The sudden onset of flashes of light, new or significantly increased floaters, or a sensation of a curtain or shadow covering part of the vision also requires emergency care, as these can be signs of a retinal detachment or tear.
Severe eye pain accompanied by sudden vision changes, redness, or halos around lights should also prompt immediate medical evaluation, as these may indicate acute glaucoma. Vision loss following a head injury or trauma to the eye is also an emergency. While persistent blurriness, recurring discomfort, or gradual changes in vision should be discussed with an eye doctor during a routine visit, any sudden shift in visual acuity or the appearance of new symptoms necessitates urgent care.