Causes

• Use of atropine
  Atropine
  Atropine is a naturally occurring tropane alkaloid extracted from deadly nightshade , Jimson weed , mandrake and other plants of the family Solanaceae. It is a secondary metabolite of these plants and serves as a drug with a wide variety of effects...
  
   or other anticholinergics

• Presbyopia
  Presbyopia
  Presbyopia is a condition where the eye exhibits a progressively diminished ability to focus on near objects with age. Presbyopia’s exact mechanisms are not known with certainty; the research evidence most strongly supports a loss of elasticity of the crystalline lens, although changes in the...
  
   -- Difficulty focusing on objects that are close. The elderly are common victims. (Accommodation tends to decrease with age.)

• Cataracts -- Cloudiness over the eye's lens, causing poor night-time vision, halos around lights, and sensitivity to glare. Daytime vision is eventually affected. Common in the elderly.

• Glaucoma
  Glaucoma
  Glaucoma is an eye disorder in which the optic nerve suffers damage, permanently damaging vision in the affected eye and progressing to complete blindness if untreated. It is often, but not always, associated with increased pressure of the fluid in the eye...
  
   -- Increased pressure in the eye, causing poor night vision, blind spots, and loss of vision to either side. A major cause of blindness. Glaucoma can happen gradually or suddenly—if sudden, it is a medical emergency.

• Diabetic retinopathy
  Diabetic retinopathy
  Diabetic retinopathy is retinopathy caused by complications of diabetes mellitus, which can eventually lead to blindness....
  
   -- This complication of diabetes can lead to bleeding into the retina. Another common cause of blindness.

• Macular degeneration
  Macular degeneration
  Age-related macular degeneration is a medical condition which usually affects older adults and results in a loss of vision in the center of the visual field because of damage to the retina. It occurs in “dry” and “wet” forms. It is a major cause of blindness and visual impairment in older adults...
  
   -- Loss of central vision, blurred vision (especially while reading), distorted vision (like seeing wavy lines), and colors appearing faded. The most common cause of blindness in people over age 60.

• Eye infection, inflammation, or injury
  Eye injury
  Physical or chemical injuries of the eye can be a serious threat to vision if not treated appropriately and in a timely fashion. The most obvious presentation of ocular injuries is redness and pain of the affected eyes. This is not, however, universally true, as tiny metallic projectiles may cause...
  
  .

• Floaters -- Tiny particles drifting across the eye. Although often brief and harmless, they may be a sign of retinal detachment.

• Retinal detachment
  Retinal detachment
  Retinal detachment is a disorder of the eye in which the retina peels away from its underlying layer of support tissue. Initial detachment may be localized, but without rapid treatment the entire retina may detach, leading to vision loss and blindness. It is a medical emergency.The retina is a...
  
   -- Symptoms include floaters, flashes of light across your visual field, or a sensation of a shade or curtain hanging on one side of your visual field.

• Optic neuritis
  Optic neuritis
  Optic neuritis is the inflammation of the optic nerve that may cause a complete or partial loss of vision.-Causes:The optic nerve comprises axons that emerge from the retina of the eye and carry visual information to the primary visual nuclei, most of which is relayed to the occipital cortex of the...
  
   -- Inflammation of the optic nerve from infection or multiple sclerosis. You may have pain when you move your eye or touch it through the eyelid.

• Stroke
  Stroke
  A stroke, previously known medically as a cerebrovascular accident , is the rapidly developing loss of brain function due to disturbance in the blood supply to the brain. This can be due to ischemia caused by blockage , or a hemorrhage...
  
   or Transient ischemic attack
  Transient ischemic attack
  A transient ischemic attack is a transient episode of neurologic dysfunction caused by ischemia – either focal brain, spinal cord or retinal – without acute infarction...
  
  

• Brain tumor
  Brain tumor
  A brain tumor is an intracranial solid neoplasm, a tumor within the brain or the central spinal canal.Brain tumors include all tumors inside the cranium or in the central spinal canal...
  
  

• Bleeding into the eye
  Intraocular hemorrhage
  Intraocular hemorrhage is bleeding into the eyeball Intraocular hemorrhage (sometimes hemophthalmos or hemophthalmia) is bleeding (hemorrhage) into the eyeball Intraocular hemorrhage (sometimes hemophthalmos or hemophthalmia) is bleeding (hemorrhage) into the eyeball (oculus in Latin. It may be...
  
  

• Temporal arteritis
  Temporal arteritis
  Giant-cell arteritis or Horton disease is an inflammatory disease of blood vessels most commonly involving large and medium arteries of the head...
  
   -- Inflammation of an artery in the brain that supplies blood to the optic nerve.

• Migraine headaches -- Spots of light, halos, or zigzag patterns are common symptoms prior to the start of the headache. An ophthalmic migraine is when you have only visual symptoms without a headache.