Refractive Error: The most common cause of blurry peripheral vision is a refractive error, such as myopia (nearsightedness), hyperopia (farsightedness), or astigmatism. These conditions can cause blurry vision at all distances, including peripheral vision, due to the irregular shape of the cornea or lens inside the eye.

Cataracts: Cataracts are a clouding of the lens in the eye that can cause blurry vision, including peripheral vision. They are common in older adults and can be treated with surgery.
Glaucoma: Glaucoma is a group of eye conditions that can damage the optic nerve, leading to vision loss, including blurry peripheral vision. It is often associated with increased eye pressure.
Presbyopia: Presbyopia is a age-related condition that affects the ability to focus on close objects, but can also cause blurry peripheral vision due to the decreased flexibility of the lens.
Amblyopia: Amblyopia, also known as lazy eye, is a condition where the brain favors one eye over the other, causing blurry vision in the affected eye, including peripheral vision.

Retinal Detachment: Retinal detachment is a medical emergency where the retina separates from the back of the eye, causing sudden blurry vision, including peripheral vision, and potentially leading to permanent vision loss if not treated promptly.
Optic Neuritis: Optic neuritis is an inflammation of the optic nerve that can cause blurry vision, including peripheral vision, and is often associated with multiple sclerosis.
Stroke or Transient Ischemic Attack (TIA): A stroke or TIA can cause sudden vision changes, including blurry peripheral vision, and is a medical emergency requiring immediate attention.
Brain Tumors: Brain tumors, especially those affecting the optic nerve or visual pathway, can cause blurry peripheral vision and other visual disturbances.

Uveitis: Uveitis is an inflammation of the uvea, the middle layer of the eye, which can cause blurry vision, including peripheral vision, and is often associated with autoimmune disorders or infections.
Syphilis: Syphilis is a bacterial infection that can cause a range of eye problems, including blurry peripheral vision, especially in the later stages of the disease.
Toxoplasmosis: Toxoplasmosis is a parasitic infection that can cause eye problems, including blurry peripheral vision, especially in people with weakened immune systems.
Leber's Hereditary Optic Neuropathy: Leber's hereditary optic neuropathy is a rare genetic disorder that can cause sudden vision loss, including blurry peripheral vision, especially in young adults.