Defining "Blindness"

Defining "Blindness"

The two leading causes of “blindness” are macular degeneration and diabetic retinopathy.  The purpose of this site is to underscore the importance of providing legitimate and credible information for those with either disease.  If you were to believe everything you read, on the internet, or otherwise, you might feel that patients with either diabetes or macular degeneration are destined to become “blind.”

Not so.  They may, but they usually don’t.  Patients with either diabetic retinopathy or macular degeneration usually enjoy good, functional vision

Please define blindness.

There are four types of blindness.  I don’t deal with two of them.  They are (my own definitions);

1.  Complete Blindness (non-sighted blindness, no vision at all)

2. Legal Blindness (partially sighted)

3.  Refractive blindness (needs glasses)

4.  Psychological blindness (self-explanatory)

Complete Blindness (non-sighted blindness) – Another term, a doctor term, for non-sighted blindness, is “no light perception.” The terms are pretty self explanatory.  These people can not see anything.  They can not see light, they can not see the broad side of a barn, people’s faces, etc.  Stevie Wonder, Ray Charles and Helen Keller come to mind.  Patients that are no light perception (NLP) in both eyes usually require a guide dog or cane to get around.

Diabetic retinopathy can cause complete blindness if the proliferative phase of the disease causes severe retinal detachment.  This is pretty unusual.  Patients who have macular degeneration will NEVER achieve this level of blindness.

I don’t see completely blind patients.  Unfortunately, there is nothing to offer.

Legal Blindness (partially sighted) is the most common use of the term “blindness.”  When you read that diseases can cause blindness, this is not truly, truly accurate.  Legal blindness is defined as the the inability to see 20/200, or better, with the best possible glasses.

At the level of 20/200, people have difficulty performing the activities of daily living without risking injury to self or others.  For instance, a legally blind person can not safely walk around his home, operate appliances such as a stove, write a check, see TV or computers and probably can not read or drive.  A legally blind person can see larger objects, may recognize people up close and tell the direction of the sun (very important psychologically to be able to tell the “time” of day).

(20/200 vision means that I what I see at 2o feet, a “normal” person could see standing 200 feet away.)

Macular degeneration and diabetic retinopathy can cause legal blindness.  When you hear that these two diseases are the leading causes of blindness in the world; they are really the leading causes of “legal blindness.”

I treat patients with legal blindness everyday.  Remember, macular degeneration and diabetic retinopathy are the two leading causes of “legal” blindness.  Incidentally, patients that have their best vision at 20/200, or worse, are legally blind and may qualify for a tax deduction.

Refractive Blindness I wrote a short post (“What is Best Corrected Vision”) on this a few months ago, although I hadn’t come up with the term.  Regardless, these are people who really can see, they just need glasses.  Probably most of these individuals are, in fact, legally blind without their glasses.  They have no disease, have no disability and just need glasses or contacts.

Psychological Blindness There are many examples of psychiatric disease causing blindness.  These people need to be treated by a psychologist/psychiatrist.

Disclaimer:  The information contained in this posting should only be used as a reference.  Should you have additional questions contact your tax attorney or local IRS office.

U.S. Treasury Circular 230 Notice: Any tax information contained in this communication (including any attachments) was not intended or written to be used, and cannot be used, for the purpose of (1) avoiding penalties that may be imposed under the Internal Revenue Code or by any other applicable tax authority; or (2) promoting, marketing or recommending to another party any tax-related matter addressed herein.


Randall V. Wong, M.D.
Ophthalmologist, Retina Specialist

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  • Fruzsi
    Posted at 13:40h, 01 October Reply

    Hooray for a logical description to what can be confusing terminology. This is exactly the kind of infomation that someone with retinal disease seeks.

  • Pingback:Legal blindness caused by macular degeneration and diabetic retinopathy.
    Posted at 05:33h, 01 May Reply

    […] can cause both types while macular degeneration generally causes just legal blindness.  Other types of blindness are actually perceived; what I call “refractive” blindness and psychological […]

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