Types and Causes of Blindness

Blindness has several definitions and various causes. Blindness refers to different levels of non-seeing.

There are four terms used to describe different levels of vision impairment and blindness.

  • Partially sighted—partial vision in one or both eyes.
  • Low vision—visual acuity is 20/70 or poorer in the better-seeing eye and cannot be improved with glasses or contacts.
  • Legally blind—visual acuity of 20/200 or poorer in their better-seeing eye and cannot be improved with glasses or contacts..
  • Totally blind—complete loss of sight.

The most common causes of vision impairment and vision loss are diabetic retinopathy, cataracts, glaucoma, and age-related macular degeneration. The good news is that recent advances in treatments means that these conditions can be treated and in many cases vision can be preserved. 

Diabetic Retinopathy

The most common cause of blindness in working-age adults is diabetic retinopathy. Uncontrolled diabetes damages blood vessels and causes new fragile blood vessels to grow in the retina. These damaged and new fragile blood vessels leak and this leaking damages the retina and causes vision loss.

Symptoms in the advanced diabetic retinopathy can include:

  • Spots or dark strings floating in your vision (floaters)
  • Blurred vision
  • Fluctuating vision
  • Distorted vision
  • Dark or empty areas in your vision
  • Vision loss

Injections of vascular endothelial growth factor inhibitors (anti-VEGF) into the vitreous of the eye can stop the growth of the fragile and leaky blood vessels and decrease the fluid buildup.  Anti-VEGF injections are highly effective in preserving central vision when the cause is leaky blood vessels.


Cataracts are the clouding of the eye’s lens. Most cataracts develop slowly over time and cause symptoms such as blurry vision, glare or seeing halos around lights, sensitivity to bright light, changes in the way you see color.

Cataracts can be surgically removed and an artificial lens inserted to replace the lens clouded by the cataract. The surgery to remove cataracts and place an artificial lens is one of the safest and most frequently performed surgeries in the U.S. The chance of complications is extremely low; however, some people are more at risk for complications. 

The artificial lens implanted to replace the natural lens is permanent and usually does not need to be replaced. Nine out of 10 people have improved vision after cataract surgery.

Blindness from Glaucoma

Glaucoma is a group of eye diseases that damage the eye’s optic nerve and causes peripheral vision loss and sometimes blindness. It is most often caused by increased eye pressure. There are no easily detectable early symptoms for most types of glaucoma other than a gradual loss of peripheral and night vision. 

Regular eye exams can diagnose glaucoma in its early stage when it is most responsive to treatment. Glaucoma cannot be cured but it can be managed with medication or surgery.

Age-related macular degeneration (AMD)

There is a dry and wet form of macular degeneration and 90% of the cases of vision loss from macular degeneration are caused by the wet form.

In the wet form there is growth of abnormal blood vessels that leak. Because leaking blood vessels are causing the damage, wet age-related macular degeneration has the same symptoms as diabetic retinopathy.

  • Blurred vision
  • Fluctuating vision
  • Distorted vision
  • Dark or empty areas in your vision
  • Vision loss

The same anti-VEGF treatment that is used for treating diabetic retinopathy is used to treat wet age-related macular degeneration. About 95% of AMD patients achieve stabilized vision from the anti-VEGF injections and a significant percentage have some improvement in vision. 

If you would like to make an appointment, call us 609.877.2800 or EMail us.

Gregory Scimeca, M.D.
Ophthalmologist and Medical Director
The Eye Professionals

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