Eye symptoms and vision problems

Both eye injury and disease can affect vision. The clarity of vision is called visual acuity, which ranges from full vision to no vision. Acuity is usually measured on a scale that compares a person's vision at 20 feet with that of some who has full acuity. Therefore, a person who has 20/20 vision sees objects 20 feet with complete clarity, but a person with 20/200 vision sees at 20 feet what a person with full acuity sees at 200 feet.

Legal blindness is defined as visual acuity worse than 20/200 even after correction with eyeglasses or contact lenses.


Several disorders can lead to blindness including:

  • cataract, which is the most common cause and can be cured with surgery
  • infection, which is preventable and is not common in North America
  • diabetes, which is often preventable
  • macular degeneration, which affects central vision and is preventable and treatable
  • glaucoma, which is highly treatable and if treated early should not lead to blindness
Written and reviewed by the MediResource Clinical Team