Experiencing blurry vision in only the right eye, known as unilateral blurring, is a common symptom that can range from a minor annoyance to a serious medical condition. Blurriness can originate from the tear film on the surface, the lens inside, or the light-sensing tissues at the back. Because the potential causes vary greatly in severity and required treatment, any persistent or sudden change in vision necessitates a professional eye examination. This information is for general knowledge and is not a replacement for advice from an eye care professional.
Temporary Causes Related to Eye Surface and Strain
Many instances of temporary unilateral blurring are linked to the ocular surface, specifically the tear film and muscle fatigue. Dry eye syndrome is a frequent culprit, occurring when the eye does not produce enough tears or when tears evaporate too quickly. This destabilizes the tear film covering the cornea, causing light to scatter instead of focusing cleanly. Vision may fluctuate or improve momentarily with a strong blink.
Prolonged visual tasks, such as extended use of digital screens, can induce eye strain, also known as computer vision syndrome. During screen time, the blink rate decreases, exacerbating dryness and causing the focusing muscles to fatigue. This combination produces temporary blurriness, often accompanied by a gritty sensation or headache. Following the 20-20-20 rule—looking 20 feet away for 20 seconds every 20 minutes—can help alleviate this strain.
A minor corneal abrasion, or scratch on the clear front dome of the eye, is another surface-level cause. This results from a small foreign body or irritation caused by contact lens overwear. The injury disrupts the cornea’s smooth surface, scattering light and causing blurry vision, pain, and light sensitivity. While minor abrasions heal quickly, they must be checked by a professional to prevent infection.
Gradual Structural Changes Affecting Vision
Blurry vision that develops slowly often points to structural changes involving light refraction. Refractive errors, such as myopia, hyperopia, and astigmatism, occur when the shape of the eyeball, cornea, or lens prevents light from focusing precisely on the retina. Although these conditions usually affect both eyes, a significant difference in prescription between the two eyes, known as anisometropia, can make the blurriness noticeable in only one eye.
Astigmatism is a common refractive error where the cornea or lens is irregularly curved. This irregular shape causes light to focus unevenly, resulting in distorted or blurry vision at all distances. Uncorrected astigmatism can lead to persistent eye strain and headaches. Correction typically involves updated prescription lenses designed to compensate for the asymmetrical curvature.
A primary cause of gradual blurring is the formation of a cataract, which is the clouding of the eye’s naturally clear lens. As proteins within the lens clump together, they obstruct light, leading to vision that resembles looking through a foggy window. Early symptoms include progressive dimming of vision, difficulty seeing at night, and seeing halos or glare around lights. Since cataracts often progress at different rates, blurring may be noticed in one eye first.
Sudden and Serious Internal Vision Threats
When blurriness in the right eye is sudden, it may signal an acute internal threat requiring immediate attention. One emergency is a retinal detachment, where the light-sensitive tissue at the back of the eye pulls away from its underlying support layers. This separation causes the retina to lose its blood supply, resulting in a sudden, painless vision change often described as a curtain or shadow moving across the field of vision. Preceding symptoms can include a sudden increase in floaters or flashes of light.
Vascular occlusions, often called “eye strokes,” involve blockages in the blood vessels supplying the retina. A Central Retinal Artery Occlusion (CRAO) is the most severe form, resulting from a blocked artery that cuts off oxygen flow. This leads to sudden, profound, and painless vision loss. A Retinal Vein Occlusion (RVO) involves a blocked vein, causing fluid to leak, which results in a less severe, sudden blurring of vision. Both require immediate medical intervention due to the risk of irreversible damage.
Acute angle-closure glaucoma is characterized by a rapid spike in intraocular pressure. This pressure buildup occurs when the eye’s drainage angle becomes blocked, leading to optic nerve damage. The acute form presents with severe symptoms, including intense eye pain, headache, nausea, and the perception of colored halos around lights. Optic neuritis involves inflammation of the optic nerve. Its hallmark symptoms are sudden vision loss, often centrally, a noticeable loss of color vibrancy, and pain exacerbated by eye movement.
When to Seek Immediate Medical Care
Any sudden onset of vision loss or blurring in one eye requires immediate medical attention. Specific symptoms that demand immediate contact with an eye care professional or a visit to the emergency room include:
- Sudden, profound vision loss that occurs without pain.
- The appearance of a dark shadow, like a curtain being drawn, or a sudden burst of flashes and floaters.
- Severe eye pain accompanied by a headache, nausea, or the sight of colored halos around lights.
- Blurriness accompanied by pain when moving the eye and a washing out of color perception.