Low Vision Aids
Chat Highlights
May 1, 2002

Norma Devine, Editor

On Wednesday, May 1, 2002, Dr. Rick Wilson, a glaucoma specialist at Wills, and the glaucoma chat group discussed "Low Vision Aids."

Moderator:  Welcome back from Sydney, Dr. Wilson.  How was your trip?  

Dr. Rick Wilson:  Good, but they closed the mental hospital I lived in when I worked there in community psychiatry at the end of my med school days.  Made me nostalgic.

P:  Glad they let you out, Dr. Rick.  

P:  Now we know how he puts up with us! 

Moderator:  Our topic tonight is "Low Vision Aids."  Before we begin, I would like to let people know they can find low-vision computer tips at http://www.willsglaucoma.org/lowvisionhelp.htm. 

P:  Dr. Rick, what does low vision mean?

Dr. Rick Wilson:  First I'd like to say that glaucoma patients keep their central vision until late in the course of the disease. Therefore, they can see fairly clearly, but the field of view is constricted.  Sometimes it's constricted until they can just see a letter or two on the chart or a word or three on the page at near vision.   If there is any macular degeneration, that is a bad combination. The glaucoma takes the vision from 10 to 30 degrees off the central axis, and the macular degeneration takes the central vision.  Low-vision aids are very helpful with macular degeneration, but hard to get used to.

P:  What are low-vision aids?

Dr. Rick Wilson:  Optical magnification to aid in seeing distance or near material. 

P:  What low-vision aids are available for seeing at near and far distances?

Dr. Rick Wilson:  Small telescopes are good for seeing things at a distance, such as which bus is coming.  High magnification lenses at near distance necessitate holding the reading material close, often as close as six inches, and using only the better eye.

P:  How much does contrast have to do with low-vision aids, as opposed to magnification?

Dr. Rick Wilson:  Magnification can make up for contrast to some extent, but contrast will improve vision dramatically.  Contrast sensitivity is one aspect of vision that is diminished with glaucoma.  That is, patients with moderately advanced glaucoma can see black-on-white easily, but gray-on gray poorly. They may miss a concrete curb as twilight approaches.

P:  Normal-tension glaucoma often starts close to fixation, doesn't it?  Does that affect the usability of low-vision aids?

Dr. Rick Wilson:  That kind of vision loss may increase the utility of low-vision aids. 

P:  I assume low-vision aids mostly help with reading and close work.  Are there some that help people walk around?

Dr. Rick Wilson:  Low-vision aids only help when focusing on a particular object or reading material.  They do not increase the field of vision, as a rule, or increase contrast sensitivity.  Corning and Noir both make glasses, like shooting glasses, that increase contrast and help about one-third of my patients with advanced glaucoma.

P:  A man in Georgia developed a headset called the Jordy that helps patients walk around.  The Jordy uses a video camera, like a mobile CCTV.

P:  Can you say more about the lenses that help increase contrast?

Dr. Rick Wilson:  They are yellow.  Light yellow for dimly lit conditions.  Deep yellow to orange if glare and excess light are involved.  Many optical shops have a blank glass with the color or coating on the lenses so one can try them out.

P:  Have vision aids improved since I started using them in the Seventies?

Dr. Rick Wilson:  Yes, they have.  There is also a closed video camera that focuses on a platform where the reading material is placed. The magnification with it can be extreme, but may take some practice, and obviously slows the reader down.  It is great for making out and signing checks, which helps to maintain independence for some of my patients.

P:  Why are they so expensive?

Dr. Rick Wilson:  Because they are high-quality optical lenses like binoculars. 

Moderator:  Do you have to be legally blind to be considered as having low vision?

Dr. Rick Wilson:  No.  

P:  What is the definition of legal blindness?

P:  At one time here in the U.S., I was told that having vision of 20/200 or worse qualified a person as legally blind, if unable to be corrected with lenses.  

Dr. Rick Wilson:  That is true in many states.  

P:  Here in British Columbia, Canada, legal blindness is 20/200 vision or lower and a field vision of less than 20 degrees.  I am 20/400+.

Moderator:  Is there any way someone can qualify for financial aid for low-vision aids?

P:  Yes, there is.  Here in Canada I got financial help through service clubs to purchase low-vision aids.

Dr. Rick Wilson:  Here, the Lions Club and the State Association for the Blind and Partially Sighted also can help.  All the programs differ according to area, so it's best to check what's available locally.  

P:  In British Columbia and other parts of Canada, the CNIB (Canadian National Institute for the Blind) will find the vision aids that are right for you.  CNIB also has a specialized "rehab" teacher to find the best tool to optimize vision.  I used vision aids for a few years, such as CCTV (closed circuit TV), when I was in high school.  Now I can't read print much and I use Braille.  

Dr. Rick Wilson:  What are you using to participate in this chat room?  A screen magnifier?

P:  I am using Microsoft's magnifier.  My screen reader, JAWS, makes my computer crash in this chat room.

P:  Magnifiers come in different powers, small and large.  I was told the smaller the better.  Is that right?   

Dr. Rick Wilson:  It depends a great deal on the condition of the retina and nerve.  That is why it is important to see a low-vision specialist to be fitted for the lenses.  

P:  I am very myopic, so have about 10X magnification without my glasses or contacts. When the print is too small or too gray, just taking my glasses off to read works pretty well.  

Dr. Rick Wilson:  That works for me, too, as it does for anyone who is myopic (nearsighted).  The more nearsighted you are, the closer the object can be brought to the eye and the larger the image on the retina.

P:  I have developed a wrinkle in my vision, apparently caused either by the drops or by some buckling of the retina.  (I tested negative for wet macular degeneration).  Is there any vision aid that you know of for distorted vision?.  

Dr. Rick Wilson:  No.  Is your eye pressure low from surgery or drops?  That can cause wrinkling in the retina and the choroid, the vessel layer under the retina.

P:  Would you call the software programs for use on computers low-vision aids?

Dr. Rick Wilson:  Yes, I would.

P:  Are there any aids that go inside the eye? 

Dr. Rick Wilson:  Only for eyes that have opaque corneas (a keratoprosthesis), although for patients with low vision, the intraocular lens can be combined with glasses to give a mild telescopic effect.

P:  Do glaucoma and macular degeneration often occur at the same time, and thus cause very low vision?  They are two separate diseases, aren't they?

Dr. Rick Wilson:  Yes, they are two separate diseases, but the prevalence of each increases markedly with age.  They often co-exist in my elderly patients. 

P:  What is the best type of vision aid for someone with macular degeneration?

Dr. Rick Wilson:  A telescope for far, magnifying lenses for near, and closed circuit TV if the lenses don't help sufficiently.

P:  Do people with small eyes have smaller retinas, and therefore see things smaller than average?

Dr. Rick Wilson:  No, they see things more blurred because the eye is too short and images are focused behind the retina.  Magnifying lenses (thicker in the center than the edges) focus the image closer to the front of the eye and on the retina.

P:  Do all glaucoma eye drops eventually contribute to low vision?

Dr. Rick Wilson:  No, they should not have a lasting effect on vision, if they do not cause inflammation in the eye.

P:  Does extended use of pilocarpine contribute to low vision?

Dr. Rick Wilson:  Pilocarpine used chronically can result in a small pupil that does not dilate with drops.  That would cause darker vision, and if combined with a cataract, vision is worse than with just the cataract alone.

P:  We hear about electrical activity in the optic nerve, retina, etc.  This isn't the same stuff that lights our bulbs, is it?

Dr. Rick Wilson:  A chemical reaction occurs that sends a slight change in the electrical charge down the nerve from the retina. 

P:  My two-year-old son is having a refraction this weekend.  I have been told that he is extremely near sighted.  He wears glasses, but they do not seem to help his vision.  He never looks at the TV screen.  What is usually done during a refraction to find out the strength for glasses? 

Dr. Rick Wilson:  Was your two-year-old son  born prematurely?  It sounds as if there is more than just glaucoma going on.  

P:  He was born full term.

Dr. Rick Wilson:  During a refraction, different lenses are tried to see if the vision can be improved.  In the very young who do not cooperate, a beam of light is directed at the eye so it can be focused on the retina with different lenses to determine which focuses the light best.  

P:  Could the optic nerve be replaced by a fiber optic or microprocessor interface someday?

Dr. Rick Wilson:  Yes.  Bioengineers at Johns Hopkins are working on just such a device.

P:  Sign me up!

Dr. Rick Wilson:  I have been up working since 3:30 this morning, so I'm going to have to hit the sack.   Have a good week everyone.

End of highlights for May 1, 2002.

On May 8, Dr. Wilson discussed "Refracting Glaucoma Patients" in the Chat room. Click here for highlights of that meeting.

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