Low Vision
Chat Highlights
February 11, 2004

Norma Devine, Editor

On Wednesday, February 11, 2004, Dr. Scott Edmonds, Co-director, Low Vision Service at Wills, joined Dr. Rick Wilson, a glaucoma specialist at Wills, and the glaucoma chat group to discuss "Low Vision."

Moderator:  Our guest tonight is Dr. Scott Edmonds, a low-vision specialist at Wills. Welcome, Dr. Edmonds.

Dr. Rick Wilson:  Hi, Scott.  Thanks for joining us.

Dr. Scott Edmonds:  Hey, Rick. Thanks for inviting me.  

Moderator:  Dr. Edmonds, would you please tell us a little about yourself?

Dr. Scott Edmonds:  I have been a low-vision optometrist since 1980.  I trained at the William Feinbloom Center and the New York Lighthouse.  I came to Wills in 1982 to work with my wife, Dr. Susan Edmonds, in developing the low-vision rehabilitation program.  My training included a Bachelor of Science degree, a four-year optometry program, and special intern- and externships in low vision.  

P:  Is your wife also a low-vision specialist?  

Dr. Scott Edmonds:  Yes.

P:  How is low vision defined?  

Dr. Scott Edmonds:  Low vision is a reduction in vision to a point that it prevents a person from doing a specific task.

P:  I have very high nearsightedness.  The right eye is -13; the left eye is -18.  What is the parameter for low vision?

Dr. Scott Edmonds:  Low vision is often defined by reduced visual acuity; that is, best-corrected vision is less than 20/40.

P:  Does your work involve providing glasses and magnifiers or the training patients need? 

Dr. Scott Edmonds:  It involves providing optical magnifiers, combined with rehabilitation to teach a patient how to see around the damaged area of vision.

P:  What causes low vision?

Dr. Scott Edmonds:  The most common causes are macular degeneration, diabetic retinopathy, and optic nerve disease.

P:  I recall reading somewhere that no matter how good the Snellen (standard eye chart test) acuity is, if contrast sensitivity is depressed, the patient may not be able to read or write.  If the contrast of written material is low, what watt bulb do you recommend in a reading lamp with a shade that concentrates the light on the page?

Dr. Scott Edmonds:  We recommend a standard 75-watt bulb in a light with a focusing cone and a gooseneck to direct the light onto the object.  Contrast is often enhanced with filters.

P:  Will placing a piece of yellow acetate over the print improve contrast sensitivity?

Dr. Scott Edmonds:  In some cases, yes. We often grind yellow filters into a patient's glasses.

P:  Can stress and unfamiliar surroundings cause a person with low vision to see worse?

Dr. Scott Edmonds:  Stress, yes.  Low-vision patients learn a new pattern of eye movements and coordination around the area of damage.  Stressful situations often cause patients to return to their natural patterns of vision, which moves them into the blind spot.

P:  Do any low-vision patients qualify to drive a car?

Dr. Scott Edmonds:  Yes.  Driving is often the main goal of vision rehabilitation.

P:  You mention enhancing contrast sensitivity with filters.  I assume you mean special colored filters in the form of eyeglasses or clip-ons placed over regular glasses.  I sometimes have difficulty with night driving, especially in wet weather.   Is there something available to help with that?  

Dr. Scott Edmonds:  Yes, we use anti-reflective lenses to enhance night driving.

Dr. Rick Wilson:  Can you give us an idea of what you can accomplish with different levels of vision?  For example, what can be done for a glaucoma patient with a small visual field and 20/80 vision, versus a macular degeneration patient with a full visual field and 20/200 vision?

Dr. Scott Edmonds:  Yes, Rick. Your two examples are at the opposite end of our spectrum.   Patients with 20/80 vision and reduced field will often have problems with mobility rather than reading.  Low magnification is often enough to solve reading problems.  Mobility may require special training to compensate for the loss of visual field.  

The 20/200 patient has problems with reading and TV.  The 20/200 patient responds well to eccentric viewing training and moderate magnification in strong reading glasses and a telescopic lens for television and distance tasks.

P:  How does a person learn a new pattern of eye movement?  Can that be taught?

Dr. Scott Edmonds:  Yes.  We use a strong lens over the better eye to shrink the blind spot.  We then use a reading-training program to teach the brain to consistently see around the blind spot.  Vision is a learned activity.  Children with severe low vision often adapt quickly and do quite well.  We have learned from watching children perform, and have designed the rehabilitation program around that.  

P:  What does the training to compensate for loss of visual field  involve?   

Dr. Scott Edmonds:  Once we determine the proper lens to shrink the blind spot, we start with a page of single letters in large print and build an ability to go from letter to letter in a consistent manner.  Then we move on to random two-letter words, three-letter words, and then to reading.  From there, we move to smaller and smaller print.  That detailed activity rebuilds the coordination between the brain and the damaged eye.  We then return to the best refraction, often finding that the visual acuity has improved.

Moderator:  Where does the training take place and how long does it take?  

Dr. Scott Edmonds:  The training is initiated in the low-vision clinic.  The patient then works at home for 15 minutes, three times a day.  We follow up with the patient at four to six-week intervals.  At Wills, we coordinate these follow ups with the other specialty services, such as glaucoma or retina services. 

P:  Some of us live far from Philadelphia and might find it a hardship to get there.  Is the kind of rehab you provide -- especially retraining the eyes -- available elsewhere in the U.S. or abroad?

Dr. Scott Edmonds:  Most low-vision services provide vision rehabilitation services.  Most of the major eye centers have a low-vision service.

P:  When you say you use a strong lens to reduce the blind spot, are you referring to a scotoma that's interfering with vision?

Dr. Scott Edmonds:  Yes.  The size of the scotoma depends on the distance from the eye.  Strong lenses create a close focus and reduce the size of the scotoma, so the brain can learn to adapt to the scotoma and "see" around it.

P:  Is there something better than a monocular lens?  I ask because it is no help when waiting for a bus.  By the time the bus is in view, it has gone past or run over you.  

Dr. Scott Edmonds:  Success with telescopic lenses, monocular or binocular, depends on the ability to view around the damaged areas of the vision.  That is why we do basic rehabilitation with reading before introducing telescopic lenses.  Kids do the best with telescopic lenses; thus, our model of rehabilitation.

P:  What can you teach someone who lost vision in one eye? 

Dr. Scott Edmonds:  It is very hard to teach or provide rehab to one bad eye. The brain will try to use the pattern of vision from the best eye.

P:  What electronic aids are available to help those with low vision?

Dr. Scott Edmonds:  Electronic aids are often computer-based.  There are many such aids.  

P:  What does mobility training involve?  

Dr. Scott Edmonds:  Mobility training is a complex subject.  For the moderately impaired, it often involves counseling and tips on life skills.  For severe impairment, cane travel is necessary and we refer patients to a mobility trainer for those services.

P:  What is cane travel?

Dr. Scott Edmonds:  Using a thin white cane to assist travel.  The cane is swung from side to side to serve as a "feeler" for travel information.

P:  What is the difference between blind and legally blind?

Dr. Scott Edmonds:  Blind is blind, like midnight in a coal mine. Legally blind is a legal definition: 20/200 or visual fields less than 20 degrees.  Low-vision services are not indicated for the blind; most of our patients are in the legally blind range.

P:  Is it recommended that aphakic patients receive any special training to help them acclimate to using their glasses, or any special life skills they should be taught?

Dr. Scott Edmonds:  Most aphakic patients are fitted with contact lenses to normalize vision.  For those who use aphakic spectacles, we provide counseling and a bit of "in-office" training to help with the adaptation. 

P:  Regarding the aphakic spectacles, all I was told was to "wear  them a little each night for a few weeks and then you should adjust all right."  I never have.  Is there anything else that would be helpful for me to know?  

Dr. Scott Edmonds:  A person with 20/200 vision really has only lost 8% of his or her vision, but it is the 8% out of the middle that is hard to compensate.  Learning with aphakic spectacles is difficult.  The more you wear them, the quicker the adaptation.  I start the patient with watching TV, move on to walking around the house, and then move on to outside.

P:  Do people with low vision have better hearing?

Dr. Scott Edmonds:  Some say that other senses are enhanced to compensate for loss of vision.  We believe that our success with rehab is related to making patients more aware of their peripheral vision and redirect it for detail, rather than for motion.

P:  Is getting used to monovision contacts rehabilitation on a smaller scale?

Dr. Scott Edmonds:  I would say yes,  as is adjusting to bifocal contacts and other special vision situations.  Being a soft bifocal wearer, I can say it takes a couple of months to adapt!

P:  How many people in the U.S. have low vision? 

Dr. Scott Edmonds:  It's hard to get a handle on the low-vision population.  Two to three million is a rough estimate. 

Dr. Rick Wilson:  About 130,000 Americans are blind from glaucoma. 

P:  You didn't mention service dogs.  Any comment about them? 

Dr. Scott Edmonds:  Service dogs are great.  Since we do not handle the blind, the truly blind, in our clinic, I don't get a chance to work with the dogs these days.

P:  Do you have patients who play golf? 

Dr. Scott Edmonds:  Yes,  I do.  Most learn to adapt to the vision limitations without special lenses.  Tom Sullivan, a totally blind man, is one of the best golfers I know!

Moderator:  Dr. Scott it was very nice of you to join us.  I hope I never need your services.  Nothing personal.

Dr. Scott Edmonds:  You would love my bifocal contact lens work!

Dr. Rick Wilson:  Thanks again, Scott.  Everyone seems to have gotten a lot out of your discussion.  

Dr. Scott Edmonds:  My pleasure, Rick.

End of highlights for February 11, 2004.

On February 18, Dr. Wilson discussed "Medications" in the Chat room. Click here for highlights of that meeting.

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